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Two streams of wastewater from the Kraft Pulp and Paper Mills at Webuye are released from the pulping, bleaching and paper pressing departments. One stream is made up of clear wastewater and the second is made up of turbid wastewater. The wastewaters from the mills are treated using oxidation ponds, after which the treated wastewater is discharged into the River Nzoia. The wastewater was analysed for Cd, Cr, Cu, Ni, Pb, Zn, Ca, K, Mg and Na. The results are that the concentrations of Ca and Na significantly increased in the treated wastewater. The concentrations of Cd, Pb, Zn, K and Mg also increased in the treated wastewater, though not significantly. The concentrations of Cr, Cu and Ni decreased in the treated wastewater but not significantly. Mass loadings of the metals discharged into River Nzoia were calculated. It was found that the mean mass loading of two metals (Ca and Na) significantly increased in the treated wastewater. Five metals (Cd, Pb, Zn, K and Mg) increased in the treated wastewater although not significantly. Three metals (Cr, Cu and Ni) decreased in the treated wastewater but the decrease was not significant. The concentrations of Cd, Cu, Ni, Pb and Zn were all above the limits set by EC for drinking water. These findings pose serious questions of the effectiveness of oxidation ponds system to safeguard the receptor against pollutants from the pulp and paper industry at Webuye. [Copyright &y& Elsevier]

The burn pond is a relatively efficient and safe way to deal with the hydrogen emitted or leaked in experiments. The aim of this paper is to analyze the performance of the burn pond in bubbling and dispersing hydrogen. The numerical simulation is the primary method utilized in this study, with a small-scale experimental validation. And Taguchi method is proposed to process data and quantify the importance of each factor. The results show that the water depth affects the performance of the burn pond most significantly, accounting for more than 56 %, followed by the outer diameter of caps and the number of slots. In addition to these design factors, the velocity of hydrogen also has a considerable impact on the burn pond. Essentially, the four factors determine the size and kinetic energy of bubbles, which then directly affect the process of bubbling and hydrogen distribution. The conclusions provide an orientation for optimizing the parameters related to bubble caps and the burn pond. • Depth of water influences the burn pond most significantly. • Distance between the neighboring slots determines the bubbling situation. • Richardson number indicates that the flow in the bubble cap is a plume. [ABSTRACT FROM AUTHOR]

This paper introduces an evaluation of the hydrodynamic performance of the flow in the screens used on the physical unit operations in a selected full-scale wastewater treatment plant (WWTP) based on Computational Fluid Dynamics (CFD) simulations. The numerical study was carried out with the ANSYS Fluent, CFD software by using the three-dimensional (3 D), steady, incompressible flow based on the Reynolds-Average Navier-Stokes equations with three different turbulence modeling. The hydrodynamic behavior of the screening facility, combined with head pond-upstream channel-bar screens was evaluated under different conditions of the mass flow rate and velocity fields. Also, the numerical study was validated against the experimental study, which implemented in-situ measurements by Acoustic Doppler Velocimeter (ADV), and consistent results were obtained between the numerical and experimental study. Interestingly, while the Realizable (real) k-ε turbulence model with the relative error of 9.31% gave the best predicting results in the head pond, the renormalization group (RNG) k-ɛ turbulence model with the relative error of 9.05% gave the best predicting results in the upstream channel and through bar screens. As a result of the experimental measurements and CFD analyses carried out in the full-scale WWTP, the function of the screening facility was found to be incomplete. Moreover, a hydraulically improved new geometry was presented to operate the existing WWTP efficiently. [ABSTRACT FROM AUTHOR]

• Process-based environmental fate model (PESTIPOND) for dissolved pesticides is developed & tested. • PESTIPOND integrates a hydrological sub-model and the key transport, transfer, and transformation processes of dissolved pesticides in APs. • Sensitivity analysis underlines that sorption, biotransformation, and photolysis are the governing processes behind pesticide fate in APs. • PESTIPOND is designed to be integrated into surface water assessment tools to predict pesticide behavior at the watershed scale. Some artificial ponds (APs) are designed to collect part of the agricultural water fluxes and dissipate their pesticide contamination through a synergy of physicochemical processes. As part of a two-paper series, this paper describes the development of PESTIPOND, a process-based model for pesticide fate in AP. PESTIPOND comprises a hydrological model and a pesticide transfer model. A test-case simulation shows that PESTIPOND can predict the mass dynamics of different pesticides within AP compartments. Sensitivity analysis evidenced that adsorption–desorption, biotransformation, and photolysis have the most significant impact on the behavior of dissolved pesticides in APs. PESTIPOND is a promising tool for better understanding the performance of ponds and can help improve AP's efficiency in preserving water quality. A second paper addresses the application of PESTIPOND in a real-case scenario and its validation (Bahi et al., 2023a). The model can thus be integrated into landscape modeling tools (e.g., surface water assessment tools) to predict pesticide transfer at the watershed scale. [ABSTRACT FROM AUTHOR]

• Time-dependent environmental fate model (PESTIPOND) for dissolved pesticides is developed and validated. • Model accurately predicts concentrations after episodic pesticide applications. • Model quantifies the mass partition of dissolved pesticides in the water and sediments of ponds. • Model estimates the contribution of each key process behind pesticide dissipation in artificial ponds. • PESTIPOND is freely available for use and further study. Some artificial ponds (APs) are designed to collect part of the agricultural water fluxes and dissipate pesticide contamination through a synergy of physicochemical processes. APs act as buffer zones and mitigate pesticide transfer of farm plots to natural water resources. As part of a two-paper series, this paper addresses the application and validation of the PESTIPOND model. PESTIPOND is a process-based model developed to predict pesticides' behavior and distribution in APs located in drained agricultural catchments. Paper I (Bahi et al., 2023a) describes the development and sensitivity analysis of the model. PESTIPOND was applied on the Rampillon AP to characterize the fate of seven different pesticides and five monitoring periods while considering the key transfer and transformation processes. The model was assessed through various methods against the observed data in simulating pesticide dynamics. The statistical and graphical evaluation of PESTIPOND reflected a good performance except for boscalid. The sensitivity analysis and application of the model evidenced that adsorption-desorption and biotransformation in the pond water are major processes behind pesticide dissipation. Hydrophobic and lowly mobile pesticides are more likely to be bio-transformed at the water-sediment interface. This work highlights the link between the hydraulic residential time (HRT), temperature, and APs' efficiency in minimizing pesticide transfer into the environment. The model predicted that the actual efficiency of the AP covering 0.15% of the drained catchment would double if the pond's surface area covered at least 1% of the catchment. Moreover, the model's predictions evidenced that a temperature rise of 10 °C will increase the dissipation of pesticides by only 8%. PESTIPOND provides key elements that are useful to design and manage ponds with optimal efficiency. Hence, these APs can be complementary solutions to pesticide use regulation to reduce the transfer of agricultural contamination into freshwater resources. [ABSTRACT FROM AUTHOR]

• The growth of solar energy usage and solar power generated in India is exponential. • Theoretical and experimental research efforts in India on solar ponds are elaborated. • The possible scopes of applications of solar ponds in India are detailed. • Problems faced by the solar pond researchers are discussed. • Future of solar pond research in India is illustrated. Solar pond is generally a shallow artificial pool of water in which considerable temperature can be established within its lower layers by suppression of convective transport. Generally, for prevention of convection, some suitable salt solution is used. In this paper, various aspects of solar pond, in terms of both simulation and experimental research advances, practical applications, economic features, challenges faced and future prospects, particularly with respect to Indian context have been reviewed. In general, the importance and the position of India at global level in terms of solar energy harvesting potential have been discussed. Apart from conventional uses of solar ponds in process heating and salt production, their applications in water distillation and thermoelectric power generation are also highlighted. Besides, stability aspect and its importance are revisited from simulations and experimental observations. Important identified areas requiring future research and development to recognize more technically feasible solar pond-based systems include organic Rankine cycle for electrical power production, crop drying, building cooling and air-conditioning based on absorption systems, thermoelectric cooling, and integration of solar ponds with other renewable energy resources. The present literature is proposed to offer guidelines in policy making aimed at addressing various societal requirements in a sustainable and affordable manner by utilizing available natural resources. [ABSTRACT FROM AUTHOR]

Pond aquaculture is the main form of aquaculture worldwide. However, there are problems with water quality being difficult to control, discharge pollution, low production quality, etc. Therefore, an efficient, low-carbon, and controllable pond system should be established. In this paper, we introduce two facilities' pond systems: a segregated pond aquaculture system (SPA) and a batch pond aquaculture system (BPA). In these two systems, we evaluated a rearing period with bream (Megalobrama amblycephala) and detected ecological and economic indexes such as yield, nitrogen and phosphorus conversion efficiency, and energy utilization efficiency in different aquaculture pond systems. The results showed that the yields of the SPA and BPA were 12.81 % and 74.29 %, respectively, greater than those of traditional ponds. The feed conversion ratios (FCRs) of the BPA and SPA were 1.8 and 2.1, respectively, but those of the traditional ponds were 2.3. The proportions of nitrogen converted to fish in the SPA, BPA, and traditional ponds were 29.67 %, 33.45 %, and 26.19 %, respectively, and the percentages of phosphorus converted to fish in the SPA, BPA and traditional ponds were 53.68 %, 63.38 %, and 52.20 %, respectively. With the production of 1 kg of aquatic products, the utilization of solar and feed energy in the SPA, BPA, and traditional ponds was 60.28 ± 1.12 MJ/kg, 66.59 ±0.26 MJ/kg, and 37.05 ±1.33 MJ/kg, respectively. In addition, the SPA and BPA can also use 60 % less water, reduce wastewater discharge by 80 % and use 35 % less land. These results showed that construction facility pond systems could improve pond aquaculture efficiency and have great development potential. [ABSTRACT FROM AUTHOR]

We measured fluxes of methane, a suite of non-methane hydrocarbons (C2–C11), light alcohols, and carbon dioxide from oil and gas produced water storage and disposal ponds in Utah (Uinta Basin) and Wyoming (Upper Green River Basin) United States during 2013–2016. In this paper, we discuss the characteristics of produced water composition and air-water fluxes, with a focus on flux chamber measurements. In companion papers, we will (1) report on inverse modeling methods used to estimate emissions from produced water ponds, including comparisons with flux chamber measurements, and (2) discuss the development of mass transfer coefficients to estimate emissions and place emissions from produced water ponds in the context of all regional oil and gas-related emissions. Alcohols (made up mostly of methanol) were the most abundant organic compound group in produced water (91% of total volatile organic concentration, with upper and lower 95% confidence levels of 89 and 93%) but accounted for only 34% (28 to 41%) of total organic compound fluxes from produced water ponds. Non-methane hydrocarbons, which are much less water-soluble than methanol and less abundant in produced water, accounted for the majority of emitted organics. C6–C9 alkanes and aromatics dominated hydrocarbon fluxes, perhaps because lighter hydrocarbons had already volatilized from produced water prior to its arrival in storage or disposal ponds, while heavier hydrocarbons are less water soluble and less volatile. Fluxes of formaldehyde and other carbonyls were low (1% (1 to 2%) of total organic compound flux). The speciation and magnitude of fluxes varied strongly across the facilities measured and with the amount of time water had been exposed to the atmosphere. The presence or absence of ice also impacted fluxes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Barriers to microalgal mass cultivation depend on the value of the final product. • Low value products such as biofuels have the greatest barriers to production. • Different cultivation systems and strategies present a subset of barriers. Economically successful microalgal mass cultivation is dependent on overcoming several barriers that contribute to the cost of production. The severity of these barriers is dependent on the market value of the final product. These barriers prevent the commercially viable production of algal biofuels but are also faced by any producers of any algal product. General barriers include the cost of water and limits on recycling, costs and recycling of nutrients, CO 2 utilization, energy costs associated with harvesting and biomass loss due to biocontamination and pond crashes. In this paper, recent advances in overcoming these barriers are discussed. [ABSTRACT FROM AUTHOR]

• A Hydro-environmental model developed to model fate and transport of bacteria. • Inverness stormwater pond in Calgary, Alberta, Canada, was used to test the model. • Volume of Fluid and sediment transport models improved the simulation of bacteria. • The middle of the pond was found as the optimal location for withdrawal for reuse. • Tree barriers are shown to reduce transport of bacteria toward the optimal location. This paper presents a three-dimensional CFD based hydro-environmental model that simulates fate and transport of bacteria in water bodies. The model numerically solves unsteady incompressible Reynolds-Averaged Navier-Stokes equations on a structured grid. Free-floating and particle-attached bacteria were modelled separately regarding both fate and transport. Therefore, a sediment transport model was integrated into the main model in order to model particle-attached bacteria transport. In addition, Volume of Fluid approach was implemented to capture the water surface movements. Wind effect was also considered in the modelling using shear stress on the water surface. Since stormwater reuse is the source of some public health concerns, a stormwater pond was chosen as the test case for the model. The model was applied to simulate the distribution of bacterial indicator organisms in the Inverness Stormwater Pond in Calgary, Alberta, which is a large T-shaped pond with several inlets and outlets. The bacteria distribution in the pond was simulated for three rain events that occurred in the area. In six locations of the pond the modelled bacteria distribution was compared to collected data using non-dimensional bacteria concentrations. The comparison showed good agreement and indicated that the middle of the pond, close to the surface had the lowest levels of bacteria and thus, was considered the optimal location for withdrawal for reusing pond water. Furthermore, planting a tree barrier on the north bank of the West wing of the pond was shown to mitigate bacteria transport away from the inlets into the pond body and substantially decrease the risk of contamination at the optimal water withdrawal location. [ABSTRACT FROM AUTHOR]

• Stepwise improved biophysical model is reusable for reduced and extended cases. • The studied food web models are sensitive to initial concentrations of plankton. • Model improvement requires parallel measurements to decrease sampling errors. • Programmable Process Structure serves as an extensible method to support reuse. • Reusability check contributes to the development of scaling-up and planning models. Given the increasing importance of data- and model-driven design and control in food production systems, this paper addresses the need to improve the reproducibility, replicability, and reusability of datasets, models, and modeling frameworks. While sensor data and machine learning-based control and operation of agricultural and aquacultural systems face reproducibility and replicability challenges, reusability is becoming critical for computational model-based design and planning of complex processes. This study evaluates the reusability of an existing pond aquaculture model and outlines a systematic, stepwise approach for reusability enhancements. The suggested methodology starts with an established reference model of a typical production fishpond and improves its reusability through pilot-scale experiments, covering key aspects of pond farming technologies. The reference model is subjected to stepwise reusability checks using measured data from the respective pilot units, progressing from simpler (reduced) to more complex (extended) cases. Each step concludes with the necessary parameter or sub-model refinements, which remain unchanged in subsequent steps. The refined model is validated with the measured data from other pilot experiments. This process can be repeated until satisfactory results are obtained. The resulting model is then tested to scale up a production pond model using limited case-specific input data. In addition, a hypothetically modified scenario is studied to address discrepancies between measured and simulated data. [ABSTRACT FROM AUTHOR]

Antibiotics are causing widespread concern as one of the emerging contaminants. There is the abuse of antibiotics in high-density open aquaculture, and the tailwater is often discharged into surrounding rivers. At the same time, the water replenishment of open aquaculture ponds from nearby rivers containing antibiotic contamination from different sources may result in cross-contamination. However, it is still unclear which pollution intensity is greater in rivers or in open aquaculture. So in this paper, the levels of 20 antibiotics (i.e., Fluoroquinolones (FQs), Sulfonamides (SAs), Tetracyclines (TCs), Macrolides (MLs) and Lincosamides (LCs)) in rivers and high-density open aquaculture ponds were investigated in the Baini River basin in the suburbs of Guangzhou, China. The results showed that norfloxacin (NFX) was the predominant antibiotic in river and aquaculture water, with concentrations ranging from 6.12 to 156.04 ng/L and from 7.47 to 82.62 ng/L in both aquatic systems, respectively. As for the pollution intensity of antibiotics, the annual pollution contribution (28.64 kg/a) of the river water supply to open aquaculture is higher than that (10.81 kg/a) of open aquaculture to the river, which means river pollution has a greater impact on aquaculture ponds. The risk quotient (RQ) showed that the ecological risk of lincomycin (LIN), erythromycin (ERY), sulfamethoxazole (SMX), norfloxacin (NFX), ciprofloxacin (CFX) and chlortetracycline (CTC) in rivers and aquaculture environments had high ecological risks from 1.21 to 1.81. Water interactions with contaminated rivers will result in a corresponding increase in the ecological risk of antibiotics in the aquaculture environment. Overall, according to the results, the risk of polluted rivers to open aquaculture cannot be ignored, and it is recommended that open aquaculture should use these water sources with caution, and that the water quality evaluation of aquaculture water should be increased with monitoring indicators for emerging contaminants such as antibiotics. [Display omitted] • Twenty antibiotics in a suburban river and aquaculture ponds were investigated. • Fluoroquinolones were the predominant antibiotics in all water samples. • The impact of river water supply on open aquaculture cannot be underestimated. • All five antibiotics pose ecological risks to the aquatic environment. [ABSTRACT FROM AUTHOR]

This paper evaluates two roof pond configurations combined with a water-to-air heat exchanger (WAHE). Test cells of 1.35 m × 1.35 m x 1.35 m with the same thermal properties, except for the roofs, are built in a hot-dry climate with mild winters. They are connected with a WAHE placed inside the roof pond's water by a pipe through which the indoor air is re-circulated. The first roof consists of a 0.35 m deep water pond covered with a floating polystyrene insulation 0.03 m thick, and a spray system located 0.5 m above it that operates at night. The second roof is covered with an aluminum plate separated by a 0.10 m air gap above a 0.25 m deep water pond. We ran multiple series and compared the results to a control cell that had a California energy code compliant insulated roof. Predictive equations are developed to dimension the WAHE system. Results demonstrate that the cells with roof ponds have better cooling performance than the code compliant control cell. The best performance is obtained in the cell with the WAHE operating continuously. In this case, the indoor temperature stayed below 24 °C even with ambient temperatures above 35 °C. • WAHE systems integrated in roof ponds provide an additional cooling opportunity. • Test cells have been monitored for over two years in a hot and dry climate. • The benefits of integrating WAHE in roof ponds are assessed with promising results. • Predictive equations to dimension the WAHE system are developed. [ABSTRACT FROM AUTHOR]

• Irrigation ponds have played a crucial role in the productivity of rice. • Regional farmers have maintained irrigation ponds for more than 100 years and continue to do so to date. • We are seeing an increase in the awareness of the multi-functional roles irrigation ponds play. Approximately 190,000 irrigation ponds are distributed locally in Japan. In Hyogo Prefecture, the number of irrigation ponds as of April 2015 was 38,234. Within this prefecture, the Higashi Harima region is one of the most prominent areas in terms of irrigation pond density. Therefore, we focus our present study on this region. More specifically, in this paper, we review the historical background of the irrigation ponds in the Higashi Harima region over the last several centuries. We also discuss the current situation of the irrigation ponds and new challenges, including the multi-functional benefits that promote public awareness and encourage local people to properly maintain and manage the irrigation ponds. [ABSTRACT FROM AUTHOR]

Aquaculture involves cultivating various marine and freshwater aquatic creatures within regulated environments. Monitoring the aquatic environmental conditions in real-time is crucial for successful fish farming. The Internet of Things (IoT) offers significant potential for real-time monitoring, and this paper introduces an IoT framework designed for efficient monitoring and effective control of various water-related aquatic environmental parameters. The proposed system is implemented as an embedded system utilizing sensors and an Arduino microcontroller. In cultivating pond water, diverse sensors such as pH, temperature, and turbidity sensors are deployed, with each sensor connected to an Arduino Uno-based microcontroller board. These sensors collect data from the water, which is then stored as a CSV file in an IoT cloud platform called ThingSpeak through the Arduino microcontroller. To gather data for analysis, we conducted measurements across five ponds, varying in size and environmental conditions. After getting the real-time data, we compared our experimental results with the standard reference values. As a result, we could take the decision of whether a pond is suitable for cultivating fish or not. After that, we labeled the data with 11 fish categories: Katla, sing, prawn, shrimp, rui, tilapia, pangas, karpio, magur, silver carp, and koi. The data was analyzed using 10 machine learning (ML) algorithms, including J48, Random Forest, K Nearest Neighbors (K-NN), K*, Logistic Model Tree (LMT), Reduced Error Pruning Tree (REPTree), Jumping Rule Inference with Pruned Search (JRIP), Partial Decision Trees (PART), Decision Table, and Logit boost. After experimental analyses, it was discovered that only three of the five ponds were ideal for fish farming, and those three ponds only met the required standards for pH, Temperature, Turbidity, and Conductivity. Among the state-of-art machine learning algorithms, Random Forest achieved the highest score of performance metrics as accuracy 94.42%, kappa statistics 93.5%, and Avg. TP Rate 94.4%. In addition, we calculated the Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Dissolved Oxygen (DO) for one scenario. This study includes prototype hardware details of the proposed IoT system. [ABSTRACT FROM AUTHOR]

Summary: Managed Aquifer Recharge (MAR) is a well-established practice for managing groundwater reserves in a sustainable way. In this paper, we look at the influence of temperature variations of the infiltration water in the recharged aquifer. The paper focuses on MAR systems consisting of an infiltration pond surrounded by extraction wells. A number of different 2D configurations and an operational system in the Belgian dune area are investigated using field observations and numerical modelling with SEAWAT. Seasonally varying temperature in the infiltration water results in a zonation of subsequent lower and higher temperatures in the aquifer. The impact of infiltration water temperature in the aquifer is significant but restricted to the area between the pond and extraction wells, quickly decreasing farther from the infiltration area. Colder water during winter results in a decrease of infiltration capacity which can be as high as 1.5–2 times with respect to summer infiltration. Infiltration water temperature variations equally influence residence times of the infiltrated water. In general, residence times become smaller for water infiltrated during summer and larger for water infiltrated during winter. Infiltration and extraction rate, their ratios and seasonal variability, and location of extraction wells are all contributing factors to the impact of varying temperature of the infiltration water. Finally, it is shown that temperature provides only a rough proxy for residence times of solutes because of the important conduction of heat. [Copyright &y& Elsevier]

Highlights • An analytical stochastic model developed for storm water quality control ponds. • Accuracy of the proposed model was validated comprehensively. • Use of the model for design purposes was illustrated. Abstract Storm water detention ponds are recognized as an effective type of treatment facility for urban storm water management purposes. This paper presents methodologies for the development of an analytical stochastic model describing the hydrologic operation of storm water quality control detention ponds with outflows controlled by orifices. The concept of effective storage capacity is proposed to properly represent a pond's storage in its stochastic water balance equation. The accuracy of the analytical stochastic model (ASM) is verified for many different hypothetical design cases. It is shown that the ASM for detention pond systems can provide accurate results for almost all possible design conditions. Implemented easily into a spreadsheet, the ASM provides an easy-to-use and computationally-efficient tool for analyzing the hydrologic performance of detention pond systems. The ASM can be used separately as a planning or design tool or together with continuous simulation models to help verify simulation results or reduce the number of simulation runs. [ABSTRACT FROM AUTHOR]

Highlights • Simulates the long-term suspended sediment dynamics in a stormwater pond. • Evaluates long-term impact of sedimentation on stormwater pond performance. • Explain the benefits of sediment trapping in the stormwater pond on water quality. • Explores the variation in annual sediment loading with rainfall quantities and pattern. Abstract The influence of long-term suspended sediment dynamics on stormwater pond performance should not be ignored, but is often neglected in pond design and performance evaluation. This paper provides systematic simulated quantification of long-term suspended sedimentological effects on stormwater pond performance. Integrated hydrological and two-dimensional hydro-morphodynamic modelling and simulations were carried over a 32-year period (1984–2015) covering 3896 rainfall events with a wide range of rainfall volumes, durations and intensities. Three event-based hypothetical rainfall scenarios: non-flood condition (5-year), sewer design condition (30-year), and river flood condition (100-year) rainfall events with 1-h duration, were also simulated for comparison between the traditional event-based approach and the novel approach presented in this study. Simulation results show that the flood peak attenuation and delay are more pronounced for small (<5-year) and medium (<30-year) flood events. The long-term continuous simulation results indicate that the pond provides positive annual trap efficiencies varying from 2% to 69% for 31 of 32 years, providing long-term water quality benefits downstream. However, an extreme rainfall event in year 2012 flush out the accumulated sedimentation as a shock load to the downstream river, leading to a negative trap efficiency of −11%. The spatially averaged sediment deposition rate, as predicted by the model, varies with a mean (SD) of 2 (1.34) cm/year over the study period, which resulted in a 24% loss in the pond's volume over 32 years. The impact of the loss in storage on pond flood attenuation capacity are explored at regular time intervals over the study period. The results indicate that reduction in the pond's flood attenuation capacity is relatively more pronounced for medium (30-year) and extreme (100-year) flood events than the frequent small flood (5-year) events. The variation in annual sediment loading with rainfall quantities and patterns are also explored. [ABSTRACT FROM AUTHOR]

Highlights • A new set of machine learning approaches to analyse senor data from prawn ponds. • Identification of relationships between water quality variables and yield. • A novel water quality variable data set from a prawn farm in South East Asia. Abstract A number of variables can affect the harvest yield in prawn ponds including dissolved oxygen, ammonia, pH, nitrite, and so on. A set of industry standards are there to maintain these variables within specific ranges for maintaining ideal growing environments for the prawns. However recent harvest results in a prominent prawn farm in South East Asia have shown different performance across ponds even after maintaining these variables within the industry standard ranges. An experiment was conducted recently to collect data on different influence variables (mentioned above) by measuring them at different times over the whole prawn growing season. We have conducted a set of analytical experiments on this data set using machine learning methods to answer three questions: (1) What level of predictive power do the influence variables have i.e. how well they can differentiate between good and bad performing ponds, (2) What is the relative importance of influence variables in predicting pond performance, and (3) How the perceived variables influence the harvest metrics. The paper presents a set of machine learning based analytical approaches undertaken to answer these questions. [ABSTRACT FROM AUTHOR]

Summary: This paper predicts saltwater advection in groundwater from leaky aquaculture ponds. A closed form solution for the potential function, stream function and velocity field is derived via the series solutions method. Numerically integrating along different streamlines gives the location (or advection front) of saltwater throughout the domain for any predefined upper time limit. Extending this process produces a function which predicts advection front location against time. The models considered in this paper are easily modified given knowledge of the required physical parameters. [Copyright &y& Elsevier]

Dissolved oxygen (DO) is a key ecological factor to measure the quality of water in the aquaculture. As the pond water body is affected by the breeding environment, the spatial distribution of DO shows a certain law in the entire pond. Therefore, to simulate the distribution of DO in aquaculture waters and grasp the temporal and spatial variation of DO is the key to achieving precise regulation of DO. For this purpose, this paper proposed a method for simulating the temporal and spatial distribution of DO in pond culture based on a sliding window-temporal convolutional network together with trend surface analysis (SW-TCN-TSA). This paper first utilized SW to construct DO data sets with different prediction durations, and then used the improved TCN model to realize one-dimensional time series prediction for DO at single monitoring point. Based on the prediction results of DO, a TSA method was performed on the predicted values of DO at the extreme moments of all discrete monitoring points, so as to realize the simulation of the temporal and spatial distribution of DO in the pond. Experimental results show that the SW-TCN model has better prediction performance for one-dimensional time series prediction of DO. Compared with traditional deep networks, such as CNN, GRU, LSTM, CNN-GRU and CNN-LSTM, the values of evaluation indicators (MSE, MAE and RMSE) have been greatly improved. In the process of trend surface fitting, all fitting R2 of DO at different water depths are higher than 0.9, indicating that the TSA can accurately reflect the temporal and spatial distribution of DO. This method can provide a basis for the prediction and early warning of DO in the three-dimensional space of the pond and has high practicability in aquaculture. • The accurate time series prediction of DO based on SW-TCN has been realized. • A TSA method was used to simulate temporal and spatial distribution of DO in different water layers. • The proposed method can realize the early warning of DO in the three-dimensional space of the pond. [ABSTRACT FROM AUTHOR]

Abstract: Active filters, which facilitate phosphorus (P) removal via precipitation and/or adsorption, offer a promising ‘appropriate technology’ for upgrading small wastewater treatment systems. Research on active filters for P removal using steel slag material has been conducted in laboratories across the world, however, field experiments have been limited and long-term data is practically non-existent. This paper presents a decade of experience on P removal by active slag filters at a full-scale treatment plant. During 1993–1994 the filter removed 77% of the total phosphorus (TP), and over the first 5 years of the filter''s operation it reduced the mean effluent TP concentration to 2.3mgl−1. However during the sixth year of operation P removal was significantly reduced. Over the 11 years of monitoring, 22.4tonnes of TP was removed by the filter, 19.7tonnes of this in the first 5-year period. It was determined that the slag material maintained its maximum removal potential until reaching a P-retention ratio of 1.23kg TP per tonne of slag. This paper provides the first long-term field data for slag filters, and shows that they can provide P removal for a half a decade before filter replacement/rejuvenation is required. [Copyright &y& Elsevier]

In eutrophic freshwater ecosystems, submerged macrophyte communities are replaced by phytoplankton or free-floating plants. In isolated wetlands, vegetation shift occurs over short time scales and leads to water deoxygenation and chemically reduced sediments, conditions that favor the generation, accumulation and degassing of greenhouse gases (GHGs, i.e. CH 4 , CO 2 and N 2 O) to the atmosphere. However, the relationship between primary producer's growth forms, hydrological connectivity and GHGs concentration is poorly studied in the literature. A set of 18 freshwater wetlands including isolated and river-connected oxbow lakes, marshes and ponds with different vegetation growth forms was therefore monitored monthly on the annual scale. Potential GHGs diffusive fluxes towards the atmosphere were calculated and compared with direct measurements reported in peer-reviewed papers within a meta-analysis. Our results demonstrate a strong link between the colonization of free-floating plants and the onset of hypoxic conditions and accumulation of dissolved methane. Methane and carbon dioxide concentration peaked in late summer, when floating-leaved and free-floating vegetation covered 100% of the water surface. Carbon dioxide accumulation was particularly evident at hydrological connected wetlands, where nitrate pollution was likely responsible for the concomitant increment of dissolved nitrous oxide. As an increasing number of studies focuses on unravelling environmental drivers of GHGs emission from small lakes and ponds, we encourage to systematically consider the vegetation growth forms and the hydrological connectivity as major drivers of GHGs accumulation and evasion rates. • Eutrophic small waterbodies are supersaturated in greenhouse gases. • Free-floating plants dominance favors hypoxic conditions and accumulation of CH 4 and CO 2. • In hydrologically connected wetlands nitrate loads favor N 2 O supersaturation. • Vegetation shift and nitrate input lead to increased GHG emissions. [ABSTRACT FROM AUTHOR]

In the last decade, studies have focused on identifying the most suitable microalgal species for coupled high rate algal pond (HRAP) wastewater treatment and resource recovery. However, one of the challenges facing outdoor HRAP systems is maintaining microalgal species dominance. By increasing our understanding of the environmental drivers of microalgal community composition within the HRAP environment, it may be possible to manipulate the system in such a way to favour the growth of desirable species. In this paper, we investigate the microalgal community composition in two full-scale HRAPs over a 23-month period. We compare wastewater treatment performance between dominant species and identify the environmental drivers that trigger change in community composition. A total of 33 microalgal species were identified over the 23-month period but species richness (the number of species present at any given time) was low and was not related to either productivity or nutrient removal efficiency. Species turnover of the dominant microalgae happened rapidly, typically <1 week. Changes in the influent NH 4 -N concentration and zooplankton grazer numbers were significantly associated with species turnover, accounting for 80% of the changes in dominant species throughout the 23-month study period. Both nutrient removal and biomass production did not differ between the two HRAPs when the dominant species was the same or differed in the two ponds. These results suggest that microalgal functional groups are more important than individual species for full-scale HRAP performance. This study has increased our understanding of some of the environmental drivers of the microalgae within the HRAP environment, which may assist with improving wastewater treatment and resource recovery. [ABSTRACT FROM AUTHOR]

A better design instruction for waste stabilization ponds is needed due to their growing application for wastewater purification, increasingly strict environmental regulations, and the fact that most of previous design manuals are outdated. To critically review model-based designs of typical pond treatment systems, this paper analyzed more than 150 articles, books, and reports from 1956 to 2016. The models developed in these publications ranged from simple rules and equations to more complex first-order and mechanistic models. From a case study on all four approaches, it appeared that rules of thumb is no longer a proper tool for pond designs due to its low design specification and very high output variability and uncertainty. On the other hand, at the beginning phase of design process or in case of low pressure over land and moderate water quality required, regression equations can be useful to form an idea for pond dimensions. More importantly, mechanistic models proved their capacity of generating more precise and comprehensive designs but still need to overcome their lack of calibration and validation, and overparameterization. In another case study, an essential but often overlooked role of uncertainty analysis in pond designs was investigated via a comparison between deterministic and uncertainty-based approaches. Unlike applying a safety factor representing all uncertainty sources, probabilistic designs quantify the uncertainty of model outputs by including prior uncertainty of inputs and parameters, which generates more scientifically reliable outcomes for decision makers. Based on these findings, we advise engineers and designers to shift from the conventional approaches to more innovative and economic tools which are suitable for dealing with large variations of natural biological systems. [ABSTRACT FROM AUTHOR]

Floating photovoltaic systems (FPV) can be a more sustainable alternative for the energy transition than ground-mounted photovoltaic systems, as they avoid occupying useable land and the power generation is more distributed. This paper presents the first study that calculates the FPV technical potential at the province/municipality level, focusing on water irrigation ponds, which it is a novelty in the literature that usually focuses on large water infrastructures in a national approach. In the province of Jaén (Spain), more than 3000 ponds dedicated to agricultural irrigation have been identified and their surface area and location was obtained. The results, calculated for each pond, reveal that, in a conservative scenario, in which only 25% of their surface area is covered, a minimum of 490 MWp can be installed, which can provide 251% of the province agricultural electricity consumption and 27% of the total electricity needs. This analysis has also been performed at the municipal level, where all possible FPV plants have been aggregated and compared with consumption that would be covered at this scale. Furthermore, this technology brings additional benefits, as it avoids the occupation of 12 km2 of useable land, 8.8·106 m3/year of water evaporated, while creating more than 7000 jobs. • A Technical floating PV potential assessment on water irrigation ponds is done • A Technical floating PV potential assessment at a municipal level is done • A calculation of Multi-benefits of floating PV installation is done • An energy consumption coverage assessment at municipal level with floating PV is done [ABSTRACT FROM AUTHOR]

• Propose a three-dimensional prediction model of dissolved oxygen in pond culture. • Improving the accuracy of GRU prediction model by increasing attention mechanism. • Automatic adjustment of GBRT super parameters by RS. • The three-dimensional distribution characteristics of dissolved oxygen in pond were obtained and analyzed. Pond culture is an open water body, the distribution of dissolved oxygen in water is three-dimensional. The demand for dissolved oxygen in aquatic products living in different water layers is different. The traditional one-dimensional prediction at one single monitoring point can't reflect the real situation of dissolved oxygen in different spaces in the pond. To solve these problems, a three-dimensional prediction method of dissolved oxygen based on Attention-Gated Recurrent Unit (GRU) - Gradient Boost Regression Tree (GBRT) was proposed in this paper. Firstly, the environmental factors affecting the distribution of dissolved oxygen were collected, and the dissolved oxygen prediction model of the central monitoring point was constructed using Attention-GRU. The three-dimensional coordinate system with the central monitoring point as the origin was then established, and the GBRT algorithm optimized by the Random Search algorithm(RS) was used to predict the dissolved oxygen in any position of the pond water. In the one-dimensional prediction of dissolved oxygen at the central monitoring point, the Attention-GRU model proposed in this paper had MSE of 0.121, MAE of 0.219, and RMSE of 0.348, which was a big improvement compared with LSTM model, ELM model and CNN model. In the three-dimensional prediction of dissolved oxygen in the pond, the RS-GBRT model proposed had MSE of 0.097, MAE of 0.191, and RMSE of 0.313. Compared with the models such as ExtraTree model, RandomForest model, and Bagging model, each evaluation index had been greatly improved. The experimental results indicated that the proposed method can accurately predict the dissolved oxygen in the three-dimensional space of the pond. [ABSTRACT FROM AUTHOR]

Chains of ponds are a discontinuous river type found in Australia. Their unusual morphology, important ecological functions and increasing rarity make them a priority for conservation, and yet very little research has investigated their physical structure, behaviour and evolution. This paper reconstructs the Holocene evolution and environmental history of Crisp's Creek, a headwater chain of ponds in the Southern Tablelands of NSW Australia. This history establishes baseline information on the physical template that can be used to assess a range of other biophysical processes and design appropriate river rehabilitation and management strategies for these rivers. Sedimentary aggradation began in the Late Holocene, at least 3.7–1.3 ka, broadly synchronous with aggradation phases at other sites in southeast Australia. Since European arrival in the Nineteenth Century, parts of the river incised, destroying intact ponds and smothering formerly swampy floodplains with post-incision alluvium. However, sections unaffected by incision provide a rare opportunity to examine the evolutionary trajectory of an intact variant of these rivers. This research deepens our understanding of the evolutionary context for contemporary river behaviour as relevant for designing appropriate and effective conservation and rehabilitation strategies for chains of ponds. [ABSTRACT FROM AUTHOR]

The common means of wastewater pre-treatment is impractical in large-scale wastewater treatment plants (WWTP). There is still a lack of suitable microalgae to treat raw dairy wastewater (DWW) with high organic matter concentration. For screening more diverse microalgae to treat raw DWW, the growth characteristics and metabolite production of ten algal strains cultured in undiluted DWW were studied in this paper, among which three were able to tolerate excessive chemical oxygen demand (COD) concentration and yielded high biomass concentration. Under the condition of 25 ± 1 °C and 55 μmol/m2/s, the most suitable strain were Scenedesmus SDEC-13, Chlorella pyrenoidosa SDEC-35, and Chlorella vulgaris SDEC-34, all of which had biomass concentrations above 1.2 g/L and protein contents above 45%. Based on the feasibility of cultivating microalgae with raw DWW, an alternative alga-based WWTP strategy was provided for the first time. The most important modification was the construction of the photobioreactor (PBR) to replace hydrolytic upflow sludge bed (HUSB) reactor and remove anaerobic-aerobic (AO) pond. The dairy WWTP with a PBR unit (1.68 × 104 m3) will yield a biomass production of 1.44 × 106 kg/year while capturing 2.59 × 106 kg CO 2 /year. Through carbon comparison and economic analysis, we believe that the use of microalgal PBRs for the treatment of wastewater from dairy plants presents a cost-effective and environmentally friendly alternative for the future. And future research should focus on pilot scale photobioreactor in the natural environment and large-scale treatment of dairy wastewater. [Display omitted] • Three algal species tolerated high COD concentration and achieved excellent biomass. • Chlorella pyrenoidosa SDEC-35 obtained 50.2% protein content in dairy wastewater. • A PBR based on mixotrophic algae is a great substitute for HUSB and AO pond in WWTP. • A WWTP with an algal bioreactor unit (1.68 × 104 m3) will capture 2.59 × 106 kg CO 2 /year. [ABSTRACT FROM AUTHOR]

Due to the frequent irrigation and excessive fertilization during the rice production in China, diffuse nitrogen (N) and phosphorus (P) pollution from paddy fields has become a serious environment problem and poses great challenges to national water and food security. Considering the regional heterogeneities of climate, cultivation types and cropping systems of rice planting, many water management strategies have been proposed and implemented to control diffuse N and P pollution. However, the water management optimization at different scales (the field scale, the watershed scale and national scale) is lack of comprehensive analyzed. Here, this paper summarized the characteristics of frequent-used water managements and recommended the optimal water managements after identifying the critical risk periods of diffuse N and P runoff losses at the field scale. The effects of water management optimization on diffuse N and P pollution control at the watershed and national scale were also synthetically reviewed. The results indicated that optimized field water management decreased irrigation water use (38.7–40.0%) and reduced diffuse pollution (25.5–38.8%) without significantly compromising rice yield security (−4.20 to 6.5%). The critical risk periods of diffuse pollution were pre-flooding in the Northeast Plain, pre-flooding, regreening stage for transplanting rice (the seeding-three leaf stage for direct seeding rice) and within 2 weeks after topdressing fertilization in the Yangtze River Basin and Southeast Coast in China. The corresponding water managements for these periods has been proposed after considering the climate, precipitation and fertilization characteristics. Ditches and ponds intercepted water and nutrients and mitigated 6.0–39.0% N and P runoff losses in paddy field watersheds. Furthermore, the extensive implementation of paddy water management optimization (paddy fields, ditches and ponds) combined with other advanced agricultural measures, for example, fertilization optimization, would decrease diffuse N and P pollution by 40.7–80.8% at the watershed scale and 44.7–88.1% at the national scale, respectively. This research provided great insights into the specific characteristics of paddy water managements from the fields, watershed and national scale, proposed optimal water management strategies for the realization of sustainable rice production in China, and also summarized the emerging development trends for future research directions. [Display omitted] • Optimal paddy water managements at field, watershed and national scales were analyzed. • Optimal water managements were proposed for critical risk periods at field scale. • Future emerging prospects of paddy water managements from different scales were proposed. [ABSTRACT FROM AUTHOR]

Pesticides are a non-point source of pollution affecting the quality of drinking water supplies and aquatic environments. Many facilities are set up to reduce the transfer of pesticides from agricultural parcels into the environment, thereby preventing their input into water bodies. Artificial ponds collecting runoff and erosion fluxes represent a complementary tool for mitigating pesticide transfer. Ponds are free-water surface constructed wetlands, rarely dry out, and do not exceed 2 m in depth. Their main compartments include a water column, a sediment layer, living organisms, and suspended particles. The dissipation potential of ponds is due to a combination of physical, chemical, and biological processes that pesticides undergo in an interplay between different pond compartments. Although many studies on the dissipation potential of ponds focus on nitrates and suspended sediments, very little is known about the behavior of pesticides. Also, most studies evaluate a process individually without emphasizing its eventual interaction with other processes. Few papers address and compare mathematical formulations of pesticide transfer and transformation processes for artificial pond modeling. In this review, we investigate the interactions and contribution of multiple processes to artificial pond dissipation function by comparing their rates evaluated at different scales. We also discuss the mathematical formulations of these processes and their relationship with pesticide properties. Our evaluation suggests that quantifying the contribution of each process to pesticide dissipation in artificial ponds is an important tool for the hierarchization of dissipation processes. We believe that quantification and hierarchization may improve the estimation of overall artificial pond efficiency. We anticipate this work to be the basis for developing a process-based model of pesticide fate in artificial ponds. The model will be particularly helpful in setting up the dimensioning criteria to design performant and efficient ponds in order to mitigate pesticide transfer into the environment. [Display omitted] • Identification and formalisms of dissipation processes of pesticides in artificial ponds. • Sorption as a key process for lowly soluble and hydrophobic pesticide dissipation. • Biotransformation enhanced in water-substrate interfaces favoring microbial activity. • Interplay of processes contributes more significantly to the dissipation of pesticides. [ABSTRACT FROM AUTHOR]

Algae are potential renewable energy source that provides numerous types of biofuels. Traditional methods of algae harvesting involve high electrical energy in the range of 200–5000 watt-hour for collecting per kilogram of algae. Moreover the added chemicals during the harvesting process degrade the algae quality leading to inferior biomass feedstock. Based on a comparative analysis of the various algae harvesting methods, this paper introduce a novel robotic algae harvesting system. The focus was on algae harvesting with less energy consumption and without the use of chemical flocculants. Design dimensions and size of the robotic algae harvesting system were determined based on the size of the raceway pond where algae was harvested without any operational trouble. Two algae collection units were designed using plankton nets of 5 µm which facilitate in the collection of the algae. With torque analysis on the system design, the electrical actuators and power source for the harvester was resolved. A wireless switch control system was designed for controlling the harvester's locomotion while collecting the algae from the raceway pond. The developed system was tested in a raceway pond where it successfully collected a total of 565.67 g algae in 200 test runs in 1 h and 6 min. The estimated total electrical energy consumed by the robotic algae harvesting system to collect per kilogram of algae was 110.5 watt-hour. • A novel robotic algae harvesting system is introduced which can harvest algae with less energy and without the use of chemical flocculants. • The developed system successfully collected a total of 565.67 g algae in 200 test runs in 1 h and 6 min. • Electrical energy consumed by the robotic system to collect per kilogram of algae was 110.5 watt-hour. [ABSTRACT FROM AUTHOR]

The accumulation of sludge during fish culture has long been regarded as a serious threat to the water quality of intensive aquaculture ponds hence limiting the culture density. Frequent removal of the sludge is beneficial but hard to achieve due to a lack of practical methods that can quickly remove the sludge over a large area of the pond while minimizing the release of toxic substances into water. In this paper, an innovative sludge removing system was developed and tested against the well-known center-drain method. The sludge removing system used a series of water jets instead of suction ports to quickly remove the sludge while rotating on a circular center platform. Based on the Bernoulli's principle and the wall-jet effect, the water jets could form a concentrated flow to create a negative pressure to suck in the surrounding water thereby preventing the spread of the sludge. Numerical analyses were made to verify the flow pattern within the sludge removing system and to determine effects of critical design parameters. Performance tests were conducted for 10 weeks in four 15 m * 10 m shrimp ponds each having a 6 m diameter concrete center platform with a center drainpipe. The results show that the sludge removing system could remove 82.3–99.7% of the sludge on the platform in just 8 min using 3.2 ton of water and left less than 0.33 cm of the sludge on the platform. In contrast, the center-drain method used the same amount of water but could only remove up to 5% of the sludge and allowed the sludge to accumulate to a maximum height of 21.1 cm at the end of the experiment. Most of the sludge removal by the center-drain method occurred in the first minute, but the sludge removing system could continuously remove the sludge during its entire course of rotation around the platform. The effective radius of sludge removal by the center-drain method was less than 0.3 m, whereas the effective radius of the sludge removing system was its length, i.e., 2.8 m. The sludge removing system was modularized so that its length could be increased by connecting more sludge removing modules to have a quadratic effect on its effective area. As such, it is estimated that the sludge removing system could be effective in ponds up to 1.6 ha based on comparison with a biofloc system where proper water circulation around a center sump was accomplished. The sludge removing system could provide automatic sludge removals as frequently as wanted to help maintain the water quality in intensive aquaculture ponds thus may contribute to increasing the culture density and production. Compared to human labor, the sludge removing system may make a saving of nearly 90% of its investment in just one season. • The novel system using water jets instead of suction ports to remove the sludge. • The effective area was 85 times more than the center-drain method. • It could provide fully automatic sludge removal as frequently as needed. • You could monitor the state of the shrimp from the solids in the effluent water. • It could be effective in ponds up to 1.6 ha [ABSTRACT FROM AUTHOR]

Pollution of water resources and a lack of potable water are two important issues that city dwellers in India encounter. The passage of untreated sewage down municipal drains is one of the most significant sources of water resource pollution. In densely populated areas, effective sanitation and wastewater management is becoming increasingly difficult. In many developing nations, centralized sewage and wastewater treatment facilities serve only a section of big cities, and on-site sanitation is frequently insufficient in heavily populated areas. There is a demand for complementary and intermediate solutions. DEWATS (community-managed anaerobic decentralized wastewater treatment systems) is a good option for the possibility of relatively fast sanitation improvements in high-priority neighbourhoods where the local authority is not providing a full sanitation service. The following technical treatment modules are typically seen in DEWATS. The primary treatment consists of sedimentation ponds, settlers, septic tanks or bio digester, secondary treatment consists of anaerobic baffled reactors, anaerobic filters or anaerobic and facultative pond systems, secondary aerobic/facultative treatment consists of horizontal gravel filters and post-treatment consists of aerobic polishing ponds. The experience of India in establishing community-managed DEWATS on a large scale is examined in this review. [Display omitted] • DEWATS have been implemented in different places with suitable treatment methods matching with the community needs. • DEWATS which are connected to communal sanitation centres have the ability to bridge the gap between on-site and centralized wastewater treatment systems. • Very little data is available about the practice of DEWATS other than the handbooks available by different DEWATS implementation agencies. • This paper gives a review on the different DEWATS methods adopted in India which will impart a knowledge on the selection and implementation of different unitary process to be adopted for DEWATS process. [ABSTRACT FROM AUTHOR]

Aquaculture plays a crucial role in the global food security and nutrition supply, where China accounts for the largest market share. Although there are some studies that focus on large-scale extraction of coastal aquaculture ponds from satellite images, they have often variable accuracies and encounter misclassification due to the similar geometric characteristics of various vivid water bodies. This paper proposes an efficient and novel method that integrates the spatial characteristics and three biophysical parameters (Chlorophyll-a, Trophic State Index, and Floating Algae Index) to map coastal aquaculture ponds at a national scale. These parameters are derived from bio-optical models based on the Google Earth Engine (GEE) cloud computing platform and time series of high-resolution Sentinel-2 images. Our proposed method effectively addresses the misclassification issue between the aquaculture ponds and rivers, lakes, reservoirs, and salt pans and achieves an overall accuracy of 91 % and a Kappa coefficient of 0.83 in the Chinese coastal zone. Our results indicate that the total area of Chinese coastal aquaculture ponds was 1,039,214 ha in 2019, mainly distributed in the Shandong and Guangdong provinces. The highest aquaculture intensity occurs within the 1 km coastal buffer zone, accounting for 22.4 % of the total area. Furthermore, more than half of the Chinese coastal aquaculture ponds are concentrated in the 0–5 km buffer zone. Our method is of general applicability and thus is suitable for large-scale aquaculture ponds mapping projects. Moreover, the biophysical parameters we employ can be considered as new indicators for the classification of various water bodies even with different aquaculture species. [Display omitted] • Proposed a new remote sensing method for identifying coastal aquaculture ponds using biophysical parameters. • Addressed the issue of misclassification between aquaculture ponds and other water bodies with similar shapes. • Clarified the spatial distribution and pattern of Chinese coastal aquaculture ponds in 2019. • Biophysical parameters have great potential to distinguish different water bodies, even different aquaculture species. [ABSTRACT FROM AUTHOR]

The middle Santonian-lower Campanian carbonate-mud dominated succession deposited in the northeastern margin of the South Iberian Ramp (La Cañadilla Fm, NE Spain) shows a complex set of interfingered facies developed in a low-energy and low-gradient shallow-marine to coastal environment. Three facies belts characterize the environment reconstructed in this work: (1) a low-energy shallow marine lagoon dominated by radiolitid rudist limestones and miliolid-rich facies with variable carbonate-mud content; (2) a transitional belt with a patchy distribution of ponds and mudbanks. This belt mostly consists of miliolid-rich limestones with variable amount of fenestral porosity, which are interfingered with charophytes and gastropod marls and limestones usually mixed with miliolids; (3) a coastal plain with strong freshwater influence characterized by the sedimentation of marls and limestones with charophytes, gastropods and root traces and intraclastic/black pebble limestones. The studied succession is arranged in high-frequency sequences, including meter-scale parasequences bounded by widespread flooding surfaces, which stack in five larger-scale shallowing-upward sequences (6–20 m thick). The time calibration of these sequences obtained from strontium isotopes and biostratigraphic data (benthic foraminifera) suggests a major control in the sedimentation by climate-driven low-amplitude sea level oscillations formed in tune with the long- and short-eccentricity orbital cycles. Cyclic sea level rises controlled the existence of widespread flooding events in the low-gradient carbonate ramp at the onset of parasequences, which in the studied marginal areas of the South Iberian Ramp were mostly sourced from the southern Tethyan realm. Therefore, the La Cañadilla Fm provides an example of a complex shallow marine to coastal system giving rise to a mosaic distribution of carbonate-mud dominated facies, with sedimentation mostly influenced by external factors resulting in a well-defined stratigraphic architecture. The similarities with modern analogous systems such as the Ten Thousand Islands of the Florida Bay are discussed in this paper. • La Cañadilla Fm deposited in a carbonate mud-dominated coastal plain to lagoon • A transitional facies belt with mudbanks and ponds is compared to Florida analogues. • A mid Santonian-early Campanian age is precised by strontium data. • Sea-level changes driven by eccentricity cycles had major control in sedimentation. [ABSTRACT FROM AUTHOR]

Growing energy demand and water consumption have increased concerns about energy security and efficient wastewater treatment and reuse. Wastewater treatment high rate algal ponds (WWT HRAPs) are a promising technology that could help solve these challenges concurrently where climate is favorable. WWT HRAPs have great potential for biofuel production as a by-product of WWT, since the costs of algal cultivation and harvest for biofuel production are covered by the wastewater treatment function. Generally, 800–1400 GJ/ha/year energy (average biomass energy content: 20 GJ/ton; HRAP biomass productivity: 40–70 tons/ha/year) can be produced in the form of harvestable biomass from WWT HRAP which can be used to provide community-level energy supply. In this paper the benefits of WWT HRAPs are compared with conventional mass algal culture systems. Moreover, parameters to effectively increase algal energy content and overall energy production from WWT HRAP are discussed including selection of appropriate algal biomass biofuel conversion pathways. [ABSTRACT FROM AUTHOR]

With microalgal biofuels currently receiving much attention, there has been renewed interest in the combined use of high rate algal ponds (HRAP) for wastewater treatment and biofuel production. This combined use of HRAPs is considered to be an economically feasible option for biofuel production, however, increased microalgal productivity and nutrient removal together with reduced capital costs are needed before it can be commercially viable. Despite HRAPs being an established technology, microalgal photosynthesis and productivity is still limited in these ponds and is well below the theoretical maximum. This paper critically evaluates the parameters that limit microalgal light absorption and photosynthesis in wastewater HRAPs and examines biological, chemical and physical options for improving light absorption and utilisation, with the view of enhancing biomass production and nutrient removal. [ABSTRACT FROM AUTHOR]

Our knowledge on the algal community structure in waste stabilisation ponds is limited and it is unclear how physical–chemical changes affect the algal community structure and the treatment performance of waste stabilisation ponds. In the present paper we studied the spatial distribution of the algal community in a waste stabilisation pond in Cuenca (Ecuador) and found that the distribution was associated with the BOD concentration of the system. At the upstream end of the facultative pond where the BOD value is relatively high (74 mg L −1 ), the community is dominated by motile algal species such as Euglena and Cryptophytes. More downstream, the algal community is more evenly distributed ( G = 0.26 > 0.18) and also non-motile species such as Chlorophytes and Chrysophytes are present. Throughout the ponds, the reduction of motile algal species was associated with the decrease in BOD concentration. The dominance of Chlorophyta, Chrysophyta and Euglenophyta was highly associated with BOD concentration. Furthermore, it was concluded that the algal abundance (45541 cells mL −1 ), diversity ( D = 0.85), evenness ( G = 0.26) and richness (20.97) of the community in the maturation pond were higher than those of the facultative pond. The results of this research are valuable for a better understanding of the algae-based processes in waste stabilisation ponds. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental and numerical modelling of heat and moisture migration conducted on a composite liner comprised of a geomembrane (GMB) and a geosynthetic clay liner (GCL), over a compacted subgrade and subjected to prolonged elevated temperatures at low overburden stresses typical of brine storage ponds or solar evaporation ponds. Results are presented for a GMB sitting on a fully hydrated GCL. Heating the top of the composite liner caused a measurable increase in subgrade temperature to at least to 250 mm below the GCL. However, the presence of an air gap, simulating the presence of a wrinkle in the geomembrane, at the interface between the GMB and the GCL reduced the impact of the high temperatures on the subgrade temperature profile with depth. The change in temperature profile was accompanied by moisture migration from the GCL to the subgrade material. However no desiccation cracks were observed in the GCL and the bentonite was still in a gel form at the end of the time period investigated. Numerical modelling using finite element method (FEM) was performed to simulate the results obtained experimentally. It was found to predict accurately the temperature changes that have occurred in the subgrade material and moisture changes that occurred in both the GCL and subgrade materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel co-process of ABG, WCC and Fe powder is first proposed. • The As-bearing waste (α-Fe phase) can be separated via reduction-magnetic separation. • The weight and volume losses of As-bearing waste were 70 % and 60 %. • The As and F leached content were only 0.053 mg/L and 3.10 mg/L. • The As residual content in non-magnetic phase met standard of solid waste. Arsenic (As) -bearing gypsum sludge, one of the biggest As-bearing wastes, has seriously threatened ecological security due to the great mobility and leaching toxicity of As. Unfortunately, most of this sludge was discharged into tailing ponds without treatment. In this paper, a novel co-process of As-bearing gypsum sludge, waste carbon cathode (WCC) and Fe powder for simultaneous separation and solidification of As is proposed via reduction-magnetic separation. In the reduction process, Ca 3 (AsO 4) 2 was reduced and then enriched to α-Fe (Fe-As solid solution), and the As solidification ratio reached 90.5%. Meanwhile, NaF in waste carbon cathodes was transformed into CaF 2 and NaCa 2 FSiO 4. The As and F leached content were only 0.053 mg/L and 3.10 mg/L, when evaluated using the toxicity characteristic leaching procedure. After magnetic separation, α-Fe (magnetic phase) was separated and recovered, and the weight and volume losses of As-bearing waste were 70% and 60%, respectively, compared with the raw material. The As residual content in the non-magnetic phase met the standard of solid waste (As < 0.1 wt%), which acted as a flux during the smelting process, minimizing the environmental risk and realizing resource recycling. Moreover, waste carbon cathodes can be reused as fuel and as a reducing agent, which significantly reduces production costs. This proposed technique reduces hazardous waste, is more effective, and is also more economical. [ABSTRACT FROM AUTHOR]

Shrimp aquaculture is among the most vital sectors in the Mekong Delta of Vietnam regarding economic well-being, social aspects, and food security beyond the country boundary. Nevertheless, this sector has faced emerging challenges from increased climate variability during recent decades, negatively influencing its outcomes. This paper utilized farm-level data surveyed in 2019 to investigate the mechanisms behind households' decisions to adopt three primary climate change adaptation practices: upgrading pond dikes, lining ponds with plastic sheets, and having settling ponds. This study demonstrates the effects of adopting these strategies on shrimp farming performance. An endogenous switching regression model was employed to deal with potential selection bias and heterogeneity in the decision to adopt or not. We find that the adoption of upgrading pond dikes and having a settling pond result in higher productivity in shrimp farming, and both adopters and non-adopters of these strategies would benefit from the adaptation. As well, education of the farm operators and farmers' belief on changes in climatic conditions and their impacts on shrimp farming are the main drivers behind the adoption behavior. This study, therefore, provides empirical evidence for policymakers to promote specific climate change adaptation strategies that would improve the welfare of shrimp farmers. • Shrimp farmers' decision-making in climate change adaptation in the Mekong delta. • Education and climate belief are crucial factors of the adoption process. • Sizable effects on output stem from different primary adaptation practices. • Adaptation practices would benefit both adopters and non-adopters. • Adoption of the adaptation strategies positively links to shrimp productivity. [ABSTRACT FROM AUTHOR]

While many papers report biomethanation potential of various substrates subjected to various treatments, very few report the economic implications of their work. Here, we report a simple but effective mechanistic model, using Contois and Monod kinetics, considering only two classes of micro-organisms (a) acidogens and (b) acetomethanogens. We fitted our model to CH 4 and CO 2 evolution data from biomethanation studies of water lettuce (pistia stratiotes) inoculated with buffalo dung at five different ratios of substrate to inoculum. The data was obtained by gas chromatography. The model has been used to simulate three types of biodigestors: (a) 1-stage continuous digestor, (b) 2-stage continuous digestor and (c) semi-batch digestor with intermittent draining of digestate. The 2-stage digestor exhibited no major improvement over the 1-stage digestor presenting only a 4% increase in methane production rate with 25% longer response times. The best performance was shown by the semi-batch operation due to tolerance of high microbial loads. Biogas generated from water lettuce grown on a farm pond and using the semi-batch approach can be monetized by offsetting use of market bought LPG. The return on investment is 24.7% and 25 kg of CO 2 emissions are abated per ton of water lettuce utilized. [Display omitted] • Simple, effective mechanistic model using Contois and Monod kinetics for bioreactor design developed. • Pistia Stratiotes inoculated with buffalo dung used for biomethanation potential experiments. • Model calibrated with CO2 and CH4 evolution data from experiments. • Several reactor configurations simulated using the model. • Semi-batch 1-stage is optimum configuration, with 24.7% RoI for LPG offset. [ABSTRACT FROM AUTHOR]

Surface drainage at the neighborhood and street scales plays an important role in conveying stormwater and mitigating urban flooding. Surface drainage at the local scale is often ignored due to the lack of up-to-date fine-scale topographical information. This paper addresses this issue by providing a novel method for evaluating surface drainage at the neighborhood and street scales based on mobile lidar (light detection and ranging) measurements. The developed method derives topographical properties and runoff accumulation by applying a semantic segmentation (SS) model (a computer vision technique) and a flow direction model (a hydrology technique) to lidar data. Fifty lidar images representing 50 street blocks were used to train, validate, and test the SS model. Based on the test dataset, the SS model has 80.3% IoU and 88.5% accuracy. The results suggest that the proposed method can effectively evaluate surface drainage conditions at both the neighborhood and street scales and identify problematic low points that could be susceptible to water ponding. Municipalities and property owners can use this information to take targeted corrective maintenance actions. • The study developed a method that integrates computer vision and flow direction model to assess surface drainage condition. • This study applied the developed method to 50 street blocks in a neighborhood in Houston, Texas. • The developed model can identify key drainage and land features within a street block with an accuracy of 88.5%. • The results can show problematic areas susceptible to water ponding and inform drainage maintenance decisions. [ABSTRACT FROM AUTHOR]

Malaysia's renewable energy policies do not cover production from waste, including the generation of biogas from palm oil mill effluent. This paper combines life cycle cost-benefit analysis (LCCBA) and the analytical hierarchy process (AHP) to provide new insights into costs and benefits of technologies over the life cycles, and on the basis of this information, asks experts to rank different options to enhance policy. The results show that the continuous stirred tank reactor has a higher LCC of 0.63 Million USD/year, compared to a LCC value of 0.55 Million USD/year for the covered lagoon bio-digester. In terms of cost-benefit, the continuous stirred tank reactor has a higher net present value of 0.46 Million USD/year, higher return on investment of 10.11% and a shorter payback period of 9.9 years compared to the covered lagoon bio-digester system, which has a net present value of 0.22 Million USD/year, return on investment of 7.79% and a payback period of 12.8 years. The continuous stirred tank reactor system therefore emerges as more economically feasible compared to the covered lagoon bio-digester system. On providing this information to experts using AHP, the three top ranked policy options emerged as: i) providing detailed environmental guidelines, ii) standardising technical guidelines for biogas installation and iii) covering the open pond wall using lining. Economic insights and policy opportunities based on this research can be used to inform policy decision making in multiple contexts where biogas plant projects are under consideration, in both Malaysia and globally. • Life cycle cost-benefit analysis (LCCBA) on palm oil mill effluent treatment. • Analytical hierarchy process (AHP) ranks policy options. • Combining LCCBA and AHP offers insights linking economic analysis & policy options. [ABSTRACT FROM AUTHOR]

Abstract: The HTR/VHTR is one of the six system concept chosen within the Generation IV Forum (GIF). A great deal of research is presently being done worldwide on innovative features of this system among which safety is of major importance. One specific aspect which is deserving attention is the potential use of a confinement instead of a containment. To do so, it should be demonstrated that the confinement approach would be capable of reducing early and late offsite doses. This paper presents an analysis of the performance of postulated HTR/VHTR confinements. Two main configurations have been modeled, which major difference is the presence of pools in the vent pathway to the environment (wet confinement). These pools would provide a passive closure of the confinement once the depressurization is completed. However, it could change strongly the thermal-hydraulics and decontamination capability of the confinement. To illustrate the effect of water pools on accident scenarios and of the pool design on the confinement response, a Very Large Break accident has been simulated with the ASTEC v1.3 code. Results, given in terms of the fraction of radioactive material that would reach the environment, show that water pools strongly change the thermal-hydraulic evolution within the building. Moreover, water pools are efficient aerosol traps which scrubbing efficiency depends on their configuration (i.e., vent cross section and pool submergence). A correlation has been obtained for the decontamination factor (DF) in terms the pool geometrical features. Finally, by assuming moderate filter efficiency, the addition of filters downstream the water ponds would result in total source term attenuation ten times higher than in the case of a dry confinement. [Copyright &y& Elsevier]

Abstract: The health and environmentally friendly culture of feed-driven grass carp ponds is an important aspect in pond aquaculture research. In the present paper, the oxidoreductase activities and the organic matter content of the sediment in three polyculture models of ponds stocking mainly grass carp (Ctenopharyngodon idellus) were studied to evaluate the organic matter cycle efficiency. The results showed that the oxidoreductase activities and the organic matter content (loss on ignition, LOI) in the sediment fluctuated during the culturing period, especially in model 2. And among different months, the oxidoreductase activities and LOI significantly fluctuated in July and August. During the production cycle, the accumulation of organic matter to the bottom of the different polyculture ponds was not significant. According to the dynamics of the oxidoreductases activities and LOI, model 2 was a more reasonable culture method. [Copyright &y& Elsevier]

Abstract: My life in low-cost sanitation and low-cost wastewater treatment and the use of treated wastewater in agriculture and aquaculture really has been ‘pits, pipes and ponds’ – ‘pits’ are low-cost sanitation technologies (LCST) such as VIP latrines and pour-flush toilets; ‘pipes’ are low-cost sewerage, principally condominial (simplified) sewerage; and ‘ponds’ are low-cost wastewater treatment systems, especially waste stabilization ponds, and the use of treated wastewater in agriculture and aquaculture. ‘Pits’ were mainly working on World Bank LCST research projects, with fieldwork principally in Zimbabwe, ‘pipes’ were working on condominial sewerage projects in Brazil and disseminating this LCST to a wider global audience, and ‘ponds’ were waste stabilization ponds, with fieldwork mainly in Brazil, Colombia, Portugal and the United Kingdom, the development of aerated rock filters to polish facultative-pond effluents, and the human-health aspects of treated wastewater use in agriculture and aquaculture, with fieldwork in Brazil and the UK, and the application of quantitative microbial risk analysis. The paper provides a professional perspective and lessons from historical developments and gives recommended future directions based on my career working on low-cost sanitation technologies and treated wastewater use in agriculture and aquaculture. [Copyright &y& Elsevier]

Abstract: In this paper, we assess the performance of fuzzy inference systems (FISs) and the consistency of fuzzy rules generated from a meta-analysis exploring diversity–environment relationships, in a system of temporary and fluctuating ponds located in two regions of southern England. The analyses focus on aquatic coleopteran assemblages, which act as excellent surrogates of wider freshwater macroinvertebrate diversity. Evaluated FISs were calibrated using evolutionary algorithms and the consistency of the rules examined using a consistency index specifically developed in this work. The best fit accounted for 76% of observed variability in the Shannon diversity index across ponds in the validation phase, which was 56 points better than the benchmark value established by a generalized additive model (GAM). The analysis of fuzzy rules indicated that the basic dynamics of this system are controlled by 8 rules. Another 10 complementary rules were detected, suggesting that more than a single dimension controlled the dynamics of the system. Therefore, water beetle diversity appears to be driven by a relatively short set of rules which relate diversity and environmental factors in a non-linear manner. These rules can be grouped according to their consistency levels, which reflect differences in coleopteran community composition. [Copyright &y& Elsevier]

Abstract: Since open ponds are considered to be a proper means to produce microalgae biomass at large scale, the design of these ponds remains a major issue in this field. Besides light intensity, the hydrodynamic characteristics are critical to obtain high microalgae productivity. Hydrodynamic mixing is required to ensure frequent exposure of algae cells to light, to avoid the settling of algae cells, to homogenize the nutrient distribution and to enhance the utilization of CO2 in the pond. However, the current design of algae ponds lacks visual assessment of hydrodynamic characteristics in the pond, resulting in the appearance of dead zones where the flow is stagnant and in the presence of non-uniform velocity throughout the pond, both of which are still major problems because of their negative impact on algae growth. Therefore, this paper describes these characteristics to support current pond design by using Computational Fluid Dynamic (CFD). In order to simulate the hydrodynamic characteristics of the pond, the variation of velocity, ratio of channel length to width (L/W), and depth of culture were performed and power consumption, dead zone volume and shear stress were evaluated. The results showed that a ratio of L/W higher than 10 yields better performance with respect to velocity uniformity and shear stress. However, power consumption increased, as well. The hydrodynamic flow in the modified pond was simulated, providing better understanding for dead zone volume reduction. To implement this modeling evaluation in the design, an experimental validation is, however, still required. [Copyright &y& Elsevier]