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Freshwater pollution is a major concern in Ghana, directly impacting human health. However, the underlying drivers of exposure and risks are not comprehensively understood, emphasizing the severity and impact of these diseases. This study assessed the interaction between water and human health, specifically focusing on the risk factors for waterborne diseases and the drivers of water pollution among residents near the Tano River Basin, Ghana. A sample size of 400 households was selected from five communities within the basin based on their proximity to the Tano River. In addition, the study combined both spatial and non-spatial data sources to map potential flood zones for the basin. The study found that inadequate sanitation, poor hygiene practices, and contamination from illegal mining were the primary causative factors of waterborne diseases. Additionally, floods and improper waste management significantly contributed to disease outbreaks. The flood susceptibility analysis indicated that areas highly susceptible to flooding cover 21.2% of the basin, predominantly in the southern part. The results highlight the urgent need for comprehensive interventions to address the drivers of waterborne diseases. This study will contribute to the local authorities in developing plans to prevent waterborne diseases and mitigate their economic and public health impacts. [ABSTRACT FROM AUTHOR]

A batch-scale electro-Fenton (EF) process was performed using graphite anode and waste battery-based Fe -Mn -Zn/C electrocatalyst coated on low-cost graphite felt cathode. The effectiveness of the EF's performance was evident with around 83.9 + 4.1% removal of 20 mg/L of sodium-dodecyl sulfate surfactant (SDS) at an optimum current density (CD) of 5.0 mA/cm2, Na2SO4 of 0.05 M, initial pH of 7.2, and electrolysis time of 180 min. Moreover, nearly 1.78-fold more removal of SDS was achieved in EF than in the electro-oxidation process operated without any catalyst. The operating cost of 0.35 $ of per m3 per order was needed to treat SDS wastewater. The remediation of SDS follows pseudo-first-order kinetics with a rate constant of 0.0095 min−1. Additionally, 90.3 + 2.1% of SDS and 57 + 2.6% of total organic carbon (TOC) removal was attained during 240 min of treatment time in secondary treated real wastewater; hence, additional 60 min of treatment time is required for effectively treating real wastewater than synthetic wastewater. Thus, EF is effective with battery waste-derived magnetic catalyst for treating wastewater containing SDS, which can lead to achieving sustainable environmental goals. HIGHLIGHTS The current work demonstrates a waste-to-treat-waste approach.; Magnetic Fe–Mn–Zn/C catalyst derived from battery waste was used in electro-Fenton.; Efficacious degradation of surfactant was obtained with a battery waste catalyst.; The kinetics of removal obtained a pseudo-first-order kinetic model.; Lauric acid was formed during sodium dodecyl sulfate degradation.;

The sediment accumulation in drainage pipes has long been recognized as a significant concern in the environmental field. This study addresses sediment accumulation in drainage pipes by introducing an innovative bioinspired approach using various shapes and angles of plates for long-term sediment reduction. Through experiments and numerical simulations, the velocity field, the turbulent kinetic energy, the head loss, and the dynamic pressure distribution in the pipeline with plates are analyzed. Results demonstrate significant increases in local velocity, dynamic pressure, and turbulence energy due to the presence of plates. The sediment reduction performance shows a positive correlation with the angle for folded plates and a non-linear relation with curvature for curved plates. Notably, the superior performance of folded plates is attributed to their exceptional ability to induce vortex formation. The head loss due to sediment reduction measures increases linearly as the angle and the curvature increase. Furthermore, the intentional induction of strong eddies and high shear flow using the undulating topography created by the locally installed folding plates in the pipeline was the main cause of sediment reduction. This novel approach holds promise for more efficient and sustainable sediment reduction in drainage systems. HIGHLIGHTS A novel measure for long-term sediment reduction inspired by dragonfly wings has been proposed.; A 25° folded plate is considered a favorable choice for this sediment reduction measure.; The main reason for sediment reduction is to induce strong eddies and high shear flow intentionally by using undulating topography.;

The ability of a composite adsorbent composed primarily of various waste materials to adsorb heavy metals, NH3-N, and chemical oxygen demand (COD) from landfill leachate was investigated through batch sorption experiments. The study determined the optimal contact time and adsorbent dosage for the removal of Pb, Zn, Cu, Fe, NH3-N, and COD to be 15, 90, 30, 180, 30, and 30 min, respectively. The corresponding optimum adsorbent dosages were determined to be 5, 30, 5, 15, 5, and 30 g, respectively. The composite adsorbent exhibited high removal efficiencies, achieving the following maximum values: 96.4% for Pb, 92.7% for Zn, 60.3% for Cu, 87.1% for Fe, 75.0% for NH3-N, and 67.5% for COD. Pb and Fe showed the best fit with a Langmuir isotherm model, with corresponding adsorption capacities of 0.0165 and 1.14 mg/g, respectively. For Zn, Cu, NH3-N, and COD, the equilibrium data demonstrated the best fit with an Elovich isotherm model, with adsorption capacities of 0.004, 0.005, 0.016, and 4.29 mg/g, respectively. The kinetic data followed the pseudo-second-order kinetic model. It presented a potential solution for the disposal of the waste from which it was derived. [ABSTRACT FROM AUTHOR]

Rearing black soldier fly is an efficient way to dispose of organic waste by converting them into protein-rich feed to substitute animal- and plant-based sources in animal feeds. The objective of this study was to determine the optimal inclusion level of black soldier fly larvae meal (BSFLM) as a substitute for soybean meal (SBM) in broiler diets and evaluate the impact on growth and carcass characteristics. Five isonitrogenous diets (D) (20% crude protein, CP) and isocaloric (3,200 Kcal/kg) were formulated such that BSFLM substituted SBM at 0% (control, D1), 25% (D2), 50% (D3), 75% (D4), and 100% (D5) on a protein basis. A total of 270 broilers (Cobb 500) were randomly assigned to the five treatments in triplicate per diet. BSFLM displayed higher fat content (44.84 ± 0.08%). Average daily feed intake (ADFI) decreased with an increase in BSFLM in the diets (p = 0.004). However, overall weight (OW) was high (1,296.97 ± 46.19 g) on 100% substitution of SBM with BSFLM (D5). Breast fat content averaged 6.06 ± 0.97 g for D1 and 15.30 ± 0.5 g for D5. This study has demonstrated that BSFLM can partially or wholly replace conventional SBM in the diet of broiler chicken. HIGHLIGHTS Black soldier fly converts organic waste into protein-rich feed for animals.; Black soldier fly larvae meal diets provided better growth for broiler chicken.; Carcass characteristics significantly improved on birds fed with black soldier fly larvae meal.;

Improper sanitation and waste management is the number one cause for ill health, disease and death throughout the world, particularly under extremely dense living conditions in refugee camps in the global South. This paper discusses the results of a mixed-method study conducted in Rohingya refugee camps, located in Chittagong, Bangladesh, currently hosting the world's largest concentration of refugees. Our structured questionnaire, group discussion and interviews were centered on waste-borne hazards. The research has evidenced severe challenges associated with overall precarious sanitation and waste situations in the camps. Garbage littering and open defecation are widely practiced. Congested drainage systems contribute to flooding, bringing waste and contaminants into people's homes. Improvements can be made by involving camp inhabitants in decision-making processes and giving them greater ownership in everyday infrastructure maintenance. Our research suggests that community participation is the key tool to maintain proper cleanliness of drains and toilets. Creating a stronger sense of community in the camps and practicing transparency and inclusion in planning and decision-making can contribute to addressing the key threats identified in this research and also apply to other refugee camps worldwide, with similar hazardous living conditions. HIGHLIGHTS Precarious sanitation infrastructure, dense living and improper waste management pose serious challenges in refugee camps.; Lack of planning, inappropriate design and the absence of participation in camp decisions are root causes for environmental contamination in refugee camps.; Community engagement and grassroots participation of refugees are vital to finding appropriate solutions to WASH issues and environmental health.;

Published literature describes the formation of the Fe (II)–phenanthroline complex (ferroin) as a stop way for Fenton processes, reducing radical yield. By contrast, this study presents evidence that ferroin can be activated by UVA in mildly acidic media in a photo-Fenton-like process. Because ferroin is the main waste from total iron determination in environmental samples, a recycling approach is suggested. Based on the best practices of waste management planning, an application of the proposed method for treating another chemical waste is presented. Titrimetric ammonia determination waste containing 2.67 mg L−1 methyl red azo dye and 1.33 mg L−1 methylene blue was degraded using the optimized experimental conditions: pH = 5.2–5.4; [H2O2] = 310 mg L−1; [ferroin] = 1.4 mg L−1; temperature = 36 ± 1 °C; reaction time = 165 min under UVA irradiation. Attenuation of most intense spectroscopic bands for the dyes achieved 94% (510 nm) and 96% (665 nm) reduction for methyl red and methylene blue, respectively, with degradation of ferroin itself. The present work brings empirical evidence that is possible to recycle ferroin as photo-Fenton-like process catalyst, as well as determine the best conditions for providing less acidic treated effluents with negligible suspended solid concentration, better than that obtained from classical photo-Fenton processes. HIGHLIGHTS Ferroin can act as a catalyst in photo-Fenton-like processes.; Degradation of azodye by modified Fenton treatment.; Drawbacks from classical Fenton processes are mitigated.; Waste acting as a catalyst for treating another waste.; Improvement for institutional waste management plan.;

Provision of safe water, sanitation, and hygiene (WASH) services in health care facilities is a priority at the global, national, and local levels. To inform improvements planning, conditions of WASH, waste management, and environmental cleaning were assessed in 81 facilities in the Autonomous Province of Vojvodina, Serbia, as part of a nationally representative survey in 2019. The survey included on-site checks, structured interviews, and drinking-water quality analysis. WHO/UNICEF indicators for WASH service levels and an advanced service level defined at the national level were applied. The results showed that all investigated facilities provided basic water services; 94% of facilities provided basic hygiene and waste management services; 58 and 2%, respectively, provided basic cleaning and sanitation services. Only 1% of investigated facilities met the basic level for all five WASH dimensions. Advanced service levels were only met for hygiene, waste management, and/or cleaning in 15-38% of facilities. In 33% of health care facilities, drinking-water quality was not in compliance with the national standards. The results revealed that there is a need for increased awareness and efforts to ensure basic provisions for sanitation, environmental cleaning, and drinking-water safety. [ABSTRACT FROM AUTHOR]

Yemen has experienced one of the world's worst cholera outbreaks in the recent history of cholera records. This study aims to identify knowledge and practices among people of Al-Mahweet governorate toward cholera infection, which can play a critical role in reducing cholera morbidity and shaping the public health response. A cross-sectional study was conducted in an area of high cholera prevalence in 2018 using structured questionnaires. Most community respondents were able to correctly identify the symptoms and risk factors of cholera. While 65% of the respondents in this study knew that proper disposal of human waste is an essential measure of cholera prevention, only 11% of the respondents knew that proper washing of fruits and vegetables lowers the risk of cholera infection. About 62.5% of households did not treat water for safe drinking. Water was scarce in about 30% of households and near-home defecation was observed in about 23%. In conclusion, this study reveals several gaps in different aspects of hygienic and preventive practices including water treatment, waste disposal, and defecation practices. Cholera response should contain comprehensive health promotion interventions to improve the public's knowledge and enhance healthy practices. Stakeholders should support communities with sustainable water and sanitation systems. [ABSTRACT FROM AUTHOR]

A comprehensive OPEX analysis for both municipal and industrial wastewaters has been conducted encompassing energy, critical component (membrane) replacement, chemicals consumption, waste disposal and labour. The analysis was preceded by a review of recent data on industrial effluent treatability with reference to published chemical oxygen demand (COD) removal data for four effluent types: food and beverage, textile, petroleum and landfill leachate. Outcomes revealed labour costs to be the most significant of those considered, contributing 50% of the OPEX for a 10,000 m³/day capacity municipal wastewater treatment works. An analysis of the OPEX sensitivity to 12 individual parameters (labour cost, flux, electrical energy cost, membrane life, feed COD, membrane cost, membrane air-scour rate, chemicals cost, waste disposal cost, mixed liquor suspended solids (MLSS) concentration, recirculation ratio, and transmembrane pressure) revealed OPEX to be most sensitive to labour effort and/or costs for all scenarios considered other than a large (100,000 m3/day capacity) works, for which flux and electrical energy costs were found to be slightly more influential. It was concluded that for small- to medium-sized plants cost savings are best made through improving the robustness of plants to limit manual intervention necessitated by unforeseen events, such as electrical/mechanical failure, foaming or sludging. [ABSTRACT FROM AUTHOR]

Trash is one of major pollutants in urban runoff. Some studies have been conducted to verify the different impacts of land use on trash generation in a qualitative way and focused on the performance of trash control measures. Few studies have explored the human impacts on trash generation or developed a quantitative model to describe the phenomenon. This paper examined the impact of human activity on trash generation. Spatial regimes on high trash generation areas were identified using the selected variables from best subset model regression and validated with Moran's I scatter plot and spatial analysis of variance. Bidirectional spatial lag regression with regimes was performed to develop the final model to explain the spatial distribution of trash generation and identify its major causes. The result showed that economic status and occupation of the population were correlated with trash accumulation and the dominant land use type, and the distance to rivers most affected trash generation. The effects of these indicators were different within and outside the high trash generation areas. [ABSTRACT FROM AUTHOR]

The presence of pharmaceutical and hormone residues in water bodies is a matter of recent global concern. This study investigated the presence of such contaminants in two urban water bodies located in the city of Santa Maria, in southern Brazil. Two urban catchments, characterized by anthropogenic influences and poor household waste collection and treatment systems, were investigated. The Cancela-Tamandaí catchment covers an area of 2.7 km², 50% of which is impervious soil, and is home to 14,300 inhabitants. The João Goulart catchment area covers 5.5 km², 40% of which is impervious soil, and houses 11,900 inhabitants. Ten sampling campaigns were conducted in each catchment. Samples were checked for diclofenac, ibuprofen, paracetamol, 17 ß-estradiol, estriol, ethisterone, estrone, and megestrol acetate. Four of the hormones (17 ß-estradiol, estriol, estrone, and megestrol acetate) were not detected in either catchment. Ethisterone was detected in a single sampling campaign in Cancela-Tamandaí. Ibuprofen and paracetamol were detected in several samples, while diclofenac was absent. The mean concentration of ibuprofen in the João Goulart catchment was 0.51 µg L-1 and in the Cancela-Tamandaí it was 1.26 µg L-1. Mean paracetamol concentrations were 0.4 µg L-1 in the João Goulart catchment and 3.0 µg L-1 in the Cancela-Tamandaí. [ABSTRACT FROM AUTHOR]

The effects of mixed feeding of boiled potato and waste activated sludge (WAS) on the performance of a microbial fuel cell (MFC) in treating solid potato waste were investigated. The coulombic efficiency (CE) of four MFCs fed with potato cubes containing 0, 48.7, 67.3 and 85.6% of boiled potato was 53.5, 70.5, 92.7 and 71.1%, respectively, indicating enhanced electricity generation and the existence of an optimum mixing ratio. The hydrolysis rate estimated using a first-order sequential hydrolysis model increased from 0.061 to 0.191 day-1, leading to shortening of the startup time for current density reaching its maximum from 25 to 5 days. The final chemical oxygen demand (COD) removal reached 85%. The CE of seven MFCs, fed with raw potato alone, sterilized/unsterilized WAS alone, and four mixed samples of raw potato with sterilized WAS at ratios of 2:1 and 4:1 and unsterilized WAS at 2:1 and 4:1, was found to be 6.1, 43.6, 0.3, 31.0, 16.5, 0.9 and 31.1%, respectively. The hydrolysis rate increased from 0.056 to 0.089 day-1, and the final COD removal changed from 39.5 to 89.6% following the order: potato alone>mixture of potato & WAS>sterilized WAS alone>unsterilized WAS alone. [ABSTRACT FROM AUTHOR]

As microalgae have the ability to simultaneously remove nutrients from wastewater streams while producing valuable biomass, microalgae-based wastewater treatment is a win--win strategy. Although recent advances have been made in this field in lab conditions, the transition to outdoor conditions on an industrial scale must be further investigated. In this work an outdoor pilot-scale membrane photobioreactor plant was operated for tertiary sewage treatment. The effects of different parameters on microalgae performance were studied including: temperature, light irradiance (solar and artificial irradiance), hydraulic retention time (HRT), biomass retention time (BRT), air sparging system and influent nutrient concentration. In addition the competition between microalgae and ammonium oxidising bacteria for ammonium was also evaluated. Maximum nitrogen and phosphorus removal rates of 12.5±4.2 mgN·L-1·d-1 and 1.5±0.4 mgP·L-1·d-1, respectively, were achieved at a BRT of 4.5 days and HRT of 2.5 days, while a maximum biomass productivity of 78± 13 mgVSS·L-1·d-1 (VSS: volatile suspended solids) was reached. While the results obtained so far are promising, they need to be improved to make the transition to industrial scale operations feasible. [ABSTRACT FROM AUTHOR]

For the simultaneous adsorption of cationic dye (methylene blue, MB) and anionic dye (reactive red 198, RR198) from aqueous solution, magnetic activated carbon (MAC) nanocomposite as a promising adsorbent was prepared and used. The concentration of MB at different time intervals was determined using a UV-Vis spectrophotometer while the concentration of RR198 was determined using a high performance liquid chromatography (HPLC) system. The effect of solution pH, contact time, adsorbent amount, and dye concentration were investigated. Also, both kinetic and isotherm experiments were studied. The optimum pH was 10 and 5.5 for adsorption of MB and RR198, respectively, and the equilibrium status was achieved after 120 min. The adsorption kinetics was controlled by the pseudo-second order kinetic model more than pseudo-first order. The best-fitted isotherms were Freundlich and Langmuir models for MB and RR198, respectively. The higher values of Freundlich adsorption capacity (Kf) for MB in comparison with RR198 refer to MAC affinity to remove cationic dyes more than anionic dyes. Apparently, there was no substantial change in the adsorption efficiency among the 10 adsorption--desorption cycles. Overall, MAC can be considered as an effective and efficient viable adsorbent for cationic and anionic dyes removal from industrial wastewaters. [ABSTRACT FROM AUTHOR]

Many industrial parks adopt a two-tier wastewater management framework whereby tenants and the park are required to build satellite and centralized wastewater treatment facilities, respectively. Due to the diversity of industrial wastewaters, the treatment process scheme in the public centralized wastewater treatment plant (WWTP) may not suit the characteristics of all effluents discharged from the tenants. In consideration of varying wastewater biodegradability, the treatment scheme in a centralized WWTP is advised to install two series of treatment processes. In detail, various effluents from the tenants shall be commingled according to their levels of biodegradability. For the non-biodegradable streams, advanced oxidation processes shall be applied in addition to biological treatments. To facilitate the grouping of effluents, each effluent will be evaluated for its biodegradability. An analytical protocol derived from OECD standard (TG302B) was developed and found effective for biodegradability assessment. A case study is described in this paper to showcase the methodology. [ABSTRACT FROM AUTHOR]

In this study, the effect of mixing on volatile fatty acid (VFA) production and composition was investigated through running five identical bench-scale reactors that were filled with primary solid and dosed with either pure glycerol or biodiesel waste. Experimental results revealed that there was an inverse correlation between the mixing intensity and the VFA production. The total VFA production in the un-mixed reactor was 9,787± 3,601 mg COD/L, whereas in the reactor mixed at 100 rpm this dropped to 3,927±1,175 mg COD/L, while both types of reactor were dosed with pure glycerol at the beginning of each cycle to reach the initial concentration of 1,000 mg/L (1,217 mg COD/L). Propionic acid was the dominant VFA in all the reactors except the reactor mixed at 30 rpm. It is hypothesized that low mixing facilitated hydrogen transfer between obligate hydrogen producing acetogens (OHPA) and hydrogen consuming acidogens in these non-methanogenic reactors. Also, in a narrower range of mixing (0 or 7 rpm), the total VFA production in biodiesel waste-fed reactors was considerably higher than that of pure glycerol-fed reactors. [ABSTRACT FROM AUTHOR]

While computational modelling has increasingly supported wastewater bioreactor engineering, novel numerical techniques have been developed such as the lattice-Boltzmann method (LBM). With vinasse treatment as case study, this work is a first step towards a comprehensive LBM simulator of a continuous-flow anaerobic packed-bed reactor. Extensions from typical models comprise onedimensional (besides time) dependence, species transport via convection and diffusion, and imposition of either Dirichlet or Danckwerts condition at inlet. The LBM simulator proved to be operational when simulating the bioreactor at different hydraulic retention times (HRTs). Simulated profiles show that stepwise feeding concentrations are smoothed as they are transported towards the bioreactor exit while concentrations increase or decrease in response to generation or degradation kinetics. Good fitting was observed for concentrations of acetic acid (2.1 kg-COD/m³ for HRT = 24 h) and butyric acid (1.3 kg-COD/m³ for HRT = 16 h) at the exit whereas other concentrations were numerically simulated at proper order of magnitude. [ABSTRACT FROM AUTHOR]

In this study, the influence of vegetation type and environmental temperature on performance of constructed wetlands (CWs) was investigated. Results of vegetation types indicated that the removal of most nutrients in polyculture was greater than those in monoculture and unplanted control. The greatest removal percentages of NH4+-N, total nitrogen (TN) and total phosphorus (TP) in polyculture were 98.7%, 98.5%, and 92.6%, respectively. In experiments of different temperatures, the removal percentages of NH4+-N, NO3--N, TN and TP in all CWs tended to decrease with the decline of temperature. Especially, a sharp decline in the removal percentages of NO3--N (decreased by above 13.8%) and TN (decreased by above 7.9%) of all CWs was observed at low temperature (average temperature of 8.9 °C). Overall, the performance of CWs was obviously influenced by temperature, and the polyculture still showed best performance in the removal of nitrogen when the average temperature dropped to 19.8 °C. Additionally, the variations of urease activities in rhizosphere soil tended to decrease with the decreasing temperature. Overall, a substantial enhancement for nitrogen and TP removal in polyculture (Canna indica + Lythrum salicaria) was observed. In conclusion, CW cultivated with polyculture was a good strategy for enhancing nutrient removal when temperature was above 19.8 °C. [ABSTRACT FROM AUTHOR]

Laccase was immobilized in polyvinyl alcohol beads containing halloysite nanotubes (PVA/HNTs) to improve the stability and reusability of enzyme. The porous structure of PVA/HNTs beads facilitates the entrapment of enzyme and prevents the leaching of immobilized laccase as well. Halloysite nanotubes act as bridge to connect the adjacent pores, facilitating the electron transfer and enhancing the mechanical properties. PVA/HNTs beads have high laccase immobilization capacity (237.02 mg/g) and activity recovery yield (79.15%), indicating it can be used as potential support for laccase immobilization. Compared with free laccase, the immobilized laccase on hybrid beads exhibits enhanced pH tolerance (even at pH 8.0), good thermal stability (57.5% of the initial activity can be maintained at 75°C), and excellent storage stability (81.17% of enzyme activity could be retained after storage at 4 °C for 5 weeks compared with that for free enzyme of 60%). Also, the removal efficiency for reactive blue can reach as high as 93.41% in the presence of redox mediator 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonate), in which adsorption and degradation exist simultaneously. The remarkable pH tolerance, thermal and storage stability, and reuse ability imply potential application of porous PVA/HNTs immobilized enzyme in environmental fields. [ABSTRACT FROM AUTHOR]

Decentralized wastewater treatment systems (DEWATS) using anaerobic treatment are increasingly being considered for wastewater treatment with options for non-potable water reuse at the community scale. One challenge for ensuring performance and reliability of DEWATS is the lack of suitable on-site sensors to monitor failure or contamination events. In this study, the aim was to use in situ fluorescence sensors to track the performance of a DEWATS, consisting of an anaerobic baffled reactor (ABR) coupled to anaerobic filter (AF) and constructed wetland (CW) treatment processes. A submersible in situ fluorometer equipped with tryptophan (TRP) and chromophoric dissolved organic matter (CDOM) sensors was deployed in each chamber of the ABR-AF-CW system, and results showed that TRP fluorescence was preferentially removed over CDOM fluorescence throughout the system. Significant relationships between TRP fluorescence and chemical oxygen demand (COD) also suggested that TRP fluorescence could be used as a surrogate for COD and soluble COD concentrations. Strong agreement between results obtained from the 1D in situ fluorometer and those obtained from a 3D benchtop fluorometer lends further support to the use of in situ fluorescence sensors to track DEWATS performance. [ABSTRACT FROM AUTHOR]

Depending on design capacity, agitators consume about 5 to 20% of the total energy consumption of a wastewater treatment plant. Based on inhabitant-specific energy consumption (kWh PE120-1 a-1; PE120 is population equivalent, assuming 120 g chemical oxygen demand per PE per day), power density (W m-3) and volume-specific energy consumption (Wh m-3 d-1) as evaluation indicators, this paper provides a sound contribution to understanding energy consumption and energy optimization potentials of agitators. Basically, there are two ways to optimize agitator operation: the reduction of the power density and the reduction of the daily operating time. Energy saving options range from continuous mixing with low power densities of 1 W m-3 to mixing by means of short, intense energy pulses (impulse aeration, impulse stirring). However, the following correlation applies: the shorter the duration of energy input, the higher the power density on the respective volume-specific energy consumption isoline. Under favourable conditions with respect to tank volume, tank geometry, aeration and agitator position, mixing energy can be reduced to 24 Wh m-3 d-1 and below. Additionally, it could be verified that power density of agitators stands in inverse relation to tank volume. [ABSTRACT FROM AUTHOR]

Crotamiton, a scabicide and antipruritic agent persistent during biological treatment processes, is frequently detected in secondary effluent. In this study, titanium dioxide (TiO2) and high-silica zeolite (HSZ-385) composites were synthesized and applied for the treatment of crotamiton in secondary effluent. Crotamiton was rapidly adsorbed by HSZ-385, and the adsorption performance of crotamiton in the secondary effluent was quite close to that in the test using ultrapure water. Even though the TiO2--zeolite composites showed lower adsorption rates than that of HSZ-385, similar crotamiton adsorption capacities were revealed using both test materials. The photocatalytic decomposition of crotamiton was significantly inhibited by the water matrix at low initial concentrations. The TiO2-zeolite composites rapidly adsorbed crotamiton from secondary effluent, and then the crotamiton was gradually decomposed under ultraviolet irradiation. Importantly, when using TiO2--zeolite composites, coexisting material in the secondary effluent did not markedly inhibit crotamiton removal at low initial crotamiton concentration. The behaviors of the main intermediates during treatment demonstrated that the main degradation intermediates of crotamiton were also captured by the composites. [ABSTRACT FROM AUTHOR]

For engineering purposes it is especially useful to be able to predict and control sewer corrosion rates and odor impacts as well as to design effective measures aiming to reduce effects related to hydrogen sulfide formation and release. Doing so, it is important to use modeling tools that are capable of assessing variations of dissolved oxygen, dissolved sulfide and hydrogen sulfide gas concentrations for a wide range of environmental scenarios. Two such models were assessed: AEROSEPT, an empirical formulation, and WATS, a conceptual and more complex approach. The models were applied to evaluate the effects of transitions between pressure mains and gravity sewers in the air--liquid mass transfer of hydrogen sulfide at the Ericeira sewer system in Portugal. This network is known to have odor and corrosion problems, especially during summer. Despite the unavoidable uncertainties due to the unsteady flow rate and the quantification of air velocity and turbulence, the simulation results obtained with both models have been shown to adequately predict the overall behavior of the system. [ABSTRACT FROM AUTHOR]

Sludges produced in biological wastewater treatment plants have rich organic materials in their characteristics. Recent research studies have focused on the energy recovery from sludge due to its high organic content. The gasification process is a thermal conversion technology transforming the chemical energy contained in a solid fuel into thermal energy and electricity. The produced syngas as a mixture of CO, CH4, H2 and other gases can be used to generate electrical energy. The gasification of yeast industry sludge has been experimentally evaluated in a pilot scale downdraft-type gasifier as a route towards the energy recovery. The gasifier has 20 kg biomass/h fuel capacity. During gasification, the temperature achieved was more than 1,000 °C in the gasifier, and then the syngas was transferred to the gas engine to yield the electricity. A load was connected to the grid box and approximately 1 kWh electrical power generation for 1 kg dry sludge was determined. The characteristics of residuals - ash, glassy material - were also analyzed. It was found that most of the heavy metals were fixed in the glassy material. Experimental results showed that the yeast industry sludge was an appropriate material for gasification studies and remarkable energy recovery was obtained in terms of power production by using syngas. [ABSTRACT FROM AUTHOR]

Water treatment plants are designed to continuously produce drinkable water, meeting defined criteria of potability. However, besides potable water, these plants produce sludges that are disposed of in the environment. The present work aimed to evaluate the sludges generated in two water treatment plants and disposed of in the margin of the Juturnaíba dam. Since alum has been used as a flocculating agent in these two plants, the concentrations of aluminum were measured in the sludges and in surface sediments. The generated piles are extremely soft to walk on and difficult to measure, so indirect modeling procedures had to be applied. The calculated mass of the sludge piles at each plant are similar and respectively 60,370 and 61,479 tons. The aluminum content of the residues, calculated according to its dosage, was 33.2 and 32.6 g kg-1 in the piles from the two plants. The amount of alum dosed to the water corresponds almost to the excess of aluminum in the sludge, compared to the sediments. It was concluded that regardless of the fact that residues are disposed of in very restricted areas, they are directly in contact with the water and may constitute a threat for the environment and humans' health. [ABSTRACT FROM AUTHOR]

Concentrations of pharmaceuticals, consisting of four anti-inflammatory and one antiepileptic drug, were studied in the aqueous and solid phase of municipal sewage sludge, collected from a wastewater treatment plant (WWTP) in central Finland. The samples included untreated municipal sludge from the biological wastewater treatment, digested sludge and sludge before and after composting. First, samples were taken as grab samples to study the bioavailable part in aqueous phase but also the part in solid fraction. Later, the long-term concentrations were studied by passive sampling with styrene divinylbenzene-reverse phase sulfonated (SDB-RPS) disks. In the untreated solid sludge, the concentrations of carbamazepine, diclofenac, ibuprofen, ketoprofen, and naproxen were 0.5 ng g-1, 26 ng g-1, 29 ng g-1, 250 ng g-1, and 13 ng g-1, while in liquid phase they were 5.6 ng L-1, 200 ng L-1, 210 ng L-1, 35 ng L-1, and 55 ng L-1, respectively. Concentrations decreased with the treatment steps but substantial amounts still occured even after the final stage. The results show that current sludge treatment cannot fully remove pharmaceuticals, leaving varying concentrations after each stage. Additionally, the results suggest that SDB-RPS disks are suitable for sampling and quantification of the bioavailable fraction of pharmaceuticals in municipal sludge. [ABSTRACT FROM AUTHOR]