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With the increase in pollution and improper waste disposal, aquatic ecosystems are experiencing escalating degradation leading to various detrimental effects, including eutrophication and adverse impacts on the health of the population reliant on these water resources. Consequently, microalgae have demonstrated efficacy in nutrient removal, minimal environmental disruption, and superior cost-effectiveness in comparison to traditional treatment methods. Thus, this study aimed to investigate wastewater treatment in an aerobic batch system, using two strains of non-axenic mixotrophic chlorophytes, Chlorella sp. and Desmodesmus sp., across distinct light regimes: continuous light exposure for 24 h, a photoperiod of 12 h light and 12 h darkness, and complete absence of light for 24 h. The Desmodesmus sp. strain exhibited superior efficiency in the proposed biological treatment, yielding more favorable nutrient removal results across all conditions, except for total nitrogen removal under the 24-h continuous light condition in which Chlorella sp. removed 0.199 ± 0.02% by biomass. In other parameters, Desmodesmus sp., remediated by biomass 0.408 ± 0.013% of inorganic phosphorus in 24 h light, 0.372 ± 0.011% of COD and 0.416 ± 0.004% of carbohydrate in 24 h dark. While Chlorella sp. removed 0.221 ± 0.01% of inorganic phosphorus in 24 h light, 0.164 ± 0.02% of COD in 24 h light and 0.214 ± 0.002% of carbohydrates in 24 h dark. Nevertheless, both strains displayed potential as viable alternatives for wastewater biological treatment, indicating that nutrient removal is achievable across all tested light conditions, albeit with variations in efficiency depending on the specific nutrient type. [ABSTRACT FROM AUTHOR]

Aerobic granules are small, dense aggregates of microbial cells that form naturally in aerobic wastewater treatment systems. They are characterized by their spherical shape, strong structural integrity, and ability to rapidly settle. These granules are formed through a self-immobilization process where different microbial species coalesce to degrade organic and inorganic compounds in wastewater. This study summarizes the development of aerobic granulation technology in wastewater treatment and the mechanism of aerobic granules' formation, analyzes the characteristics and the factors affecting the aerobic granules' formation, and presents practical engineering examples of its application from pilot-scale to full-scale operation. [ABSTRACT FROM AUTHOR]

Biological aerated filters (BAF) are attached growth aerobic systems used for the treatment of wastewater. This system can establish the physical filtration of solids along with the biological decomposition of organic matter. The performance of the BAF depends on the type of support media and its ability to meet objective of the treatment process. Natural zeolites, with properties such as ion exchange, larger surface area, capability to form biofilm, adsorption, regenerative properties etc., are a promising filter material in BAF systems. This paper investigates and discusses the effect of various factors like hydraulic retention time (HRT), carbon to nitrogen (C/N) ratio, aeration rate, depth of filter and particle size of natural zeolite which influence the performance of BAF. Based on the experimental results and optimization study using response surface methodology, carried out on the BAF system with varying process variables like HRT, C/N ratio, aeration rate and depth of filter, the natural zeolite media with particle size 1-3 mm range showed improved performance as compared to the coarser particles, that is, 3-5 mm and 5-10 mm. On conducting a final run using natural zeolite particle size of 1-3 mm under optimized value of HRT = 3.25 h, C/N = 6.2, aeration rate = 69 L/h, depth of filter = 83 cm, the BAF system observed chemical oxygen demand, biological oxygen demand, NH3-N, turbidity and total dissolved solids removal percentage of 97%, 96%, 99%, 98% and 58%, respectively. [ABSTRACT FROM AUTHOR]

There has been a lot of research on domestic wastewater treatment utilizing polymer-based supporting media. The purpose of this study is to investigate the removal of organic compounds and nutrients, as well as the kinetics of substrate removal, in a batch aerobic fixed-film system that is fed by artificial domestic wastewater and uses Polyethylene Terephthalate (PET) plastic bottles waste as supporting media. The artificial domestics wastewater feeding contains C6H12O6, NH4Cl, and KH2PO4 as carbon, nitrogen, and phosphorus sources. Artificial domestics wastewater treatment was performed at COD levels of 200, 300, 400, 500, and 600 (mg/L). The findings demonstrated that an aerobic fixed-film system wastewater treatment with PET-supporting media could remove organics and nutrients. The removal for COD 85.76 ± 0.59%, ammonia 76.59 ± 0.83%, nitrite 76.09 ± 0.66%, nitrate 64.30 ± 0.42%, TN 77.02 ± 0.94%, and TP 86.54 ± 0.68%, with the Singh's method substrate removal kinetics (k1) is 1.60 ± 0.05/hour. The benefit of supporting media from PET plastic bottle waste is contributing to plastic bottle waste reduction in Indonesia. [ABSTRACT FROM AUTHOR]

Aerobic granulation is an emerging process in wastewater treatment that has the potential to accelerate sedimentation of the microbial biomass during secondary treatment. Aerobic granulation has been difficult to achieve in the continuous flow reactors (CFRs) used in modern wastewater treatment plants. Recent research has demonstrated that the alternation of nutrient-abundant (feast) and nutrient-limiting (famine) conditions is able to promote aerobic granulation in a CFR. In this study, we conducted a metagenomic analysis with the objective of characterizing the bacterial composition of the granular biomass developed in three simulated plug flow reactors (PFRs) with different feast-to-famine ratios. Phylogenetic analyses revealed a clear distinction between the bacterial composition of aerobic granules in the pilot simulated PFRs as compared with conventional activated sludge. Larger and denser granules, showing improved sedimentation properties, were observed in the PFR with the longest famine time and were characterized by a greater proportion of bacteria producing abundant extracellular polymeric substances (EPS). Functional metagenomic analysis based on KEGG pathways indicated that the large and dense aerobic granules in the PFR with the longest famine time showed increased functionalities related to secretion systems and quorum sensing, which are characteristics of bacteria in biofilms and aerobic granules. This study contributes to a further understanding of the relationship between aerobic granule morphology and the bacterial composition of the granular biomass. [ABSTRACT FROM AUTHOR]

Small wastewater systems serving less than 10,000 population equivalents (p.e.) face a wide range of challenges due to technical and managerial capacity issues, limited resources, and the need to reduce environmental impacts. Based on the wide range of challenges of small systems, the authors of this manuscript developed the social, environmental, and economic wastewater decision support tool (SEE WWDST) to aid decision makers in comparing the sustainability of treatment alternatives. The tool uses multi-criteria decision analysis to produce a single SEE impact score that assesses 12 sustainability metrics across three larger categories: economic performance (e.g., net present worth of costs, affordability), environmental performance (e.g., carbon footprint, eutrophication, water reclaimed), and social performance (e.g., maintenance time, employee training, degree of automation, operator certification requirement, system intrusiveness, daily, and seasonal resilience). This paper compares the performance of three onsite wastewater treatment systems in Florida. The three systems evaluated include: (1) a passive septic tank effluent biofilter (STEB) system, (2) a mechanized aerobic treatment unit (ATU) system, and (3) a passive clay, sulfur, and shell biofilter (CSSB) system. The passive CSSB system was found to be the preferred system due to its lower present worth of cost, lower carbon footprint and eutrophication potential, and better performance for various social factors (e.g., maintenance time, degree of automation, system intrusiveness). The passive STEB system was the second preferred alternative, despite having a worse social performance and the highest present worth of cost. The systems were then assessed using even, social, environmental, and economic weighting preferences and a sensitivity analysis was conducted. In spite of shifts in weighting preference and changes to input data parameters to assess sensitivity, the passive CSSB system was found to be the preferred alternative. This paper highlights the importance of using triple bottom line sustainability metrics to assess small wastewater treatment alternatives using a novel decision support tool. [ABSTRACT FROM AUTHOR]

The thriving agro-industry sector accounts for an essential part of the global gross domestic product, as the need for food and feed production is rising. However, the industrial processing of agricultural products requires the use of water at all stages, which consequently leads to the production of vast amounts of effluents with diverse characteristics, which contain a significantly elevated organic content. This fact reinforces the need for action to control and minimize the environmental impact of the produced wastewater, and activated sludge systems constitute a highly reliable solution for its treatment. The current review offers novel insights on the efficiency of aerobic biosystems in the treatment of agro-industrial wastewaters and their ecology, with an additional focus on the biotechnological potential of the activated sludge of such wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Untreated and minimally treated wastewater discharged into the environment have the potential to adversely affect groundwater dependent ecosystems and nearshore marine health. Addressing this issue requires a systems approach that links land use and wastewater management decisions to potential impacts on the nearshore marine environment via changes in water quality and quantity. To that end, a framework was developed to assess decisions that have cascading effects across multiple elements of the ridge-to-reef system. In an application to Kona (Hawai'i, USA), eight land use and wastewater management scenarios were evaluated in terms of wastewater system upgrade costs and wastewater related nutrient loads in groundwater, which eventually discharge to nearshore waters, resulting in potential impacts to marine habitat quality. Without any upgrades of cesspools or the existing wastewater treatment plant (WWTP), discharges of nutrients are expected to increase substantially with permitted development, with potential detrimental impacts to the marine environment. Results suggest that converting all of the existing cesspools to aerobic treatment units (ATU) and upgrading the existing WWTP to R-1 quality provide the highest protection to nearshore marine habitat at a cost of $569 million in present value terms. Other wastewater management options were less effective but also less costly. For example, targeted cesspool conversion (a combination of septic and ATU installation) in conjunction with the WWTP upgrade still provided a substantial reduction in nutrients and potential impacts to marine habitat quality relative to the present situation at a price point roughly $100 million less than the entirely ATU option. Of note, results were more sensitive to the inclusion of the WWTP upgrade option than they were to assumptions regarding the efficiency of the cesspool conversion technologies. The model outputs also suggest that the spatial distribution of potential impacts should be carefully considered when comparing different wastewater management scenarios. When evaluated separately, the WWTP option reduced total nutrients by more than the targeted cesspool conversion option at a fraction of the cost. However, potential improvements in marine habitat quality only occurred in the immediate vicinity of the WWTP, whereas the benefits under targeted cesspool conversion were more evenly distributed along the coast. [ABSTRACT FROM AUTHOR]

Total nitrogen (TN) removal by sewage treatment required the development of nitrifying and denitrifying activities; however, these metabolite activities can produce and emit nitrous oxide (N 2 O), one of the greenhouse gases (GHG). With the expansion of sewage treatment in the world, compact systems such as moving bed biofilm reactor (MBBR) may be promising, mainly in more populated cities. However, little is known about N 2 O emission by the MBBR. This work investigated the N-NH x and TN removal, N 2 O production and emission and nitrogen mass balance in a MBBR under organic load and airflow variation. The highest TN removal (47%) was observed under higher load and higher aeration rate. Meanwhile, the MBBR under lower load and lower airflow had the lowest efficiency of TN and N-NH x removal probably due to a lower nitrifying activity. The N 2 O emission factors were lower than 1.6% (value estimated by the IPCC for sewage aerobic treatment systems). In addition, in the essay with higher load and lower airflow, half of removed TN was released by settled sludge and there is little research about this subject. Therefore, the MBBR showed to be a promising process for nitrogen removal with little emission of N 2 O even under different operational conditions that normally can occur in sanitary sewage system in cities around the world. • Importance of dissolved oxygen to N-NHx removal and nitrification activity in MBBR. • Low N 2 O emission factor in MBBR even under high aeration rate condition. • High removal of nitrogen in MBBR by settling sludge under low airflow condition. • High removal of nitrogen in MBBR by atmospheric air (as N 2) under high airflow condition. [ABSTRACT FROM AUTHOR]

Phenols are one of the most common toxic environmental pollutants in the world. The aim of this study is to explore the genotoxicity and cytotoxicity of phenols by using the Vicia faba bioassay. Moreover, the removal effects and the potential toxicological significance of phenols in semi-coking wastewater under combined treatment process were evaluated. The semi-coking wastewater treatment processes include extraction column, blowding ammonia tower, anaerobic tank, aerobic reactor, coagulator settler and adsorption column. The results showed that the genotoxic evaluation of phenolic pollutants in wastewater was performed using the Vicia faba bioassay, the concentration of phenols should lie in the range of 1–20 mg/L. The frequency of micronuclei (MCN) and the pycnosis in the root cells increased significantly, but the mitotic index decreased in a concentration-dependent manner after exposure to phenol for 12 h, which indicated that the exposure to phenol could induce oxidative stress in plant cells. In addition, fourteen kinds of phenols were detected in the semi-coking wastewater and the total concentration was 3350 mg/L, which decreased to 63.4 mg/L in the effluent of aerobic treatment unit. The total removal rate of phenols reached the value of 98%. After the coagulation and adsorption, the phenolic contaminants were almost undetectable in the effluent. The results from the genotoxicity evaluation showed that the wastewater from coagulating sedimentation unit had significant mutagenic properties. However, the MCN frequency, induced by the wastewater from the adsorption unit, did not differ much from the negative control, indicating that the adsorption treatment was required for the safety of effluent. The MCN assays of Vicia faba root are simple, efficient and reproducible methods for monitoring the genotoxicity of water contaminated with phenols. The physicochemical-biochemical combined process, as proposed in this study, was found to be suitable and efficient for treating the semi-coking wastewater. The results can provide reference for the treatment of wastewater containing high concentration phenolic substances. [ABSTRACT FROM AUTHOR]

An alternative of decentralized in-situ treatment for wastewater from condominiums based on aerobic granular biomass is proposed in this research to promote water reuse. It was demonstrated at a laboratory scale that it is possible to achieve granular biomass with this kind of wastewater. The granulation process was completed after 14 days of operation, achieving COD removal percentages of 75-90%. A compact design of a pilot plant was made to treat wastewater from a condominium of 200 people. The needed implantation area was 25.5 m2. Finally, two different alternatives of business models were studied: selling the treated water to the municipal organism or infiltrate it into groundwater. Between both options, selling the treated water allows a higher income and makes it a better alternative. [ABSTRACT FROM AUTHOR]

[Display omitted] • The alpha dynamics are an essential part of aerobic granular sludge (AGS) models. • Alpha dynamics influence energy use and simultaneous nitrification denitrification. • Process optimisation via volume exchange ratio, aeration capacity and granule size. • Soluble slowly biodegradable organics need to be considered as a state variable. • The dynamic nature of alpha affects the model calibration. The aerobic granular sludge (AGS) process treats wastewater with a significantly lower footprint and energy consumption compared to conventional activated sludge systems. Nevertheless, there is still potential for optimizing its performance, and mathematical models are most valuable tools to this end. Aeration energy consumption deserves particular attention, as it is the largest remaining operating cost for AGS systems. Batch-wisely operated reactors show an increasing oxygen transfer efficiency during aeration, which translates into a dynamic alpha factor. However, the dynamic nature of alpha is neglected in current models. The impact of this simplification on the operating performance was addressed for the first time in this study. Through the development of a novel 1-D biofilm reactor model, calibrated to a full-scale AGS plant, it was shown that the alpha dynamics affect both model structure and calibration, as well as the process performance. The description of the dynamic nature of alpha through the empirical relationship with the soluble biodegradable organic carbon required the addition of the state variable representing soluble slowly biodegradable organic carbon (S CB) to the biokinetic ASM2d model. Simulation results showed that alpha dynamics significantly influences simultaneous nitrification and denitrification and therefore need to be included in mathematical models to optimize AGS process performance. Different process variables such as volume exchange ratio, aeration capacity and granule size can be manipulated to improve reactor design and performance. The practical application of these new insights were discussed regarding the optimization of AGS systems, as well as other batch-wisely operated aerobic wastewater treatment systems. [ABSTRACT FROM AUTHOR]

Despite being a key Malaysian economic contributor, the oil palm industry generates a large quantity of environmental pollutant known as palm oil mill effluent (POME). Therefore, the need to remediate POME has drawn a mounting interest among environmental scientists. This study has pioneered the application of Meyerozyma guilliermondii with accession number (MH 374161) that was isolated indigenously in accessing its potential to degrade POME. This strain was able to treat POME in shake flask experiments under aerobic condition by utilising POME as a sole source of carbon. However, it has also been shown that the addition of suitable carbon and nitrogen sources has significantly improved the degradation potential of M. guilliermondii. The remediation of POME using this strain resulted in a substantial reduction of chemical oxygen demand (COD) of 72%, total nitrogen of 49.2% removal, ammonical nitrogen of 45.1% removal, total organic carbon of 46.6% removal, phosphate of 60.6% removal, and 92.4% removal of oil and grease after 7 days of treatment period. The strain also exhibited an extracellular lipase activity which promotes better wastewater treatment. Additionally, Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS) analyses have specifically shown that M. guilliermondii strain can degrade hydrocarbons, fatty acids, and phenolic compounds present in the POME. Ultimately, this study has demonstrated that M. guilliermondii which was isolated indigenously exhibits an excellent degrading ability. Therefore, this strain is suitable to be employed in the remediation of POME, contributing to a safe discharge of the effluent into the environment. [ABSTRACT FROM AUTHOR]

The increased number and capacity of municipal wastewater treatment plants (WWTPs) in China has driven the emission of methane (CH4). Few studies have focused on quantification of CH4 emissions from municipal WWTPs of different cities and analysis of socioeconomic factors influencing the quantity of emissions. Here we estimated CH4 emissions from WWTPs in China for 229 prefectural‐level cities, based on data from 2,019 working municipal WWTPs. The results show the total CH4 emissions to be 1,169.8 thousand tons (29.2 MtCO2e) in 2014, which is over three times that of the municipal WWTPs in the United States in 2016. Large cities along the east coast regions had larger CH4 emissions in absolute and per capita terms. Correlation analysis shows that cities with higher gross domestic product, household food consumption expenditure, or household consumption expenditure produced more degradable organics in wastewater, thus more CH4 emissions. Measures to control the sources of degradable organics and regulate WWTP processes with less emission factor are key to mitigate CH4 emissions. In addition to aerobic or anaerobic wastewater treatment systems, factors such as wastewater temperature, length of sewer, and the addition of nitrate that influencing emission factor are suggested to be involved in CH4 emission modeling. Plain Language Summary: The increased number and capacity of municipal wastewater treatment plants (WWTPs) in Chinese cities has driven the emission of methane, a potent greenhouse gas. Understanding and balancing the trade‐offs between increased municipal wastewater treatment capacity and the demands for greenhouse gas emissions reduction is a big challenge for cities in developing countries like China. We estimated methane emissions from 2,019 working municipal WWTPs in China for 229 cities. The results show the total methane emissions to be 1,169.8 thousand tons in 2014, which is over three times that of the municipal WWTPs in the United States in 2016. Large and wealth cities along the east coast regions had larger methane emissions in absolute and per capita terms. Cities with higher gross domestic product, household food consumption expenditure, or household consumption expenditure produced more degradable organics in wastewater, thus more methane emissions. Measures to control the sources of degradable organics and regulate WWTP processes are key to mitigate methane emissions. Key Points: The methane emissions from municipal wastewater treatment plants of 229 Chinese cities were 29.2 MtCO2e in 2014Large cities located in the prosperous eastern China had larger methane emissions in absolute and per capita termsCities with higher GDP, household food consumption expenditure, or household consumption expenditure tend to emit more methane [ABSTRACT FROM AUTHOR]

With the world's remarkably fast industrial development over the recent decades, the strictly controlled treatment of industrial wastewaters and effluents is becoming increasingly essential for preserving our environment. Given the importance of ensuring the compliance of industrial zones with environmental standards, it is indispensable to predict suitable wastewater treatment systems for these zones. Economic analysis of available systems, including the assessment of construction and operating costs, can greatly contribute to the selection of the treatment solution that fits a given area or application. One of the challenges in managing the treatment facilities of industrial estates, similar to the Toos Industrial Estate studied in this paper, is how to upgrade the aerobic treatment units of an existing treatment plant. In this study, the options available for upgrading the aerobic treatment unit of the studied treatment plant are reviewed and the best alternative is chosen by the use of multi-attribute decision-making methods with emphasis on operating cost minimization. The results suggest that using the economically optimum option in the studied plant will result in more than 80% reduction in the operating, energy and maintenance costs of its secondary treatment stage. [ABSTRACT FROM AUTHOR]

Abstract Chloroethenes belong to the most widely distributed groundwater contaminants. Since 2014, it has been known that trichloroethene (TCE) can be degraded aerobically and metabolically as growth substrate by a mixed bacterial enrichment culture (named SF culture). In this study, the degradation capabilities under a range of field-relevant conditions were investigated in fixed-bed reactors as well as in batch experiments. Aerobic metabolic TCE degradation was stable over the long term, with degradation optima at 22 °C and pH 7. Degradation of up to 400 μM TCE was observed. The longest starvation period after which degradation of TCE was regained was 112 days. The possible co-contaminants perchloroethene, trans -1,2-dichloroethene, and cis -1,2-dichloroethene did not inhibit TCE degradation, even though they were not degraded themselves. The presence of equimolar amounts of 1,1-dichloroethene and vinyl chloride inhibited TCE degradation. Experiments with groundwater from different chloroethene-contaminated field sites proved the potential of the SF culture for bioaugmentation. Thus, aerobic metabolic TCE degradation should be considered as a promising method for the bioremediation of field sites with TCE as the main contaminant. Graphical abstract Image 1 Highlights • Field applicability of aerobic metabolic TCE degradation. • Long-term stability of aerobic metabolic TCE degradation in fixed-bed reactors. • TCE-degrading bacteria are suitable for bioaugmentation. • Growth characteristics: pH 5–7, temperature 7–27 °C, up to 400 μM TCE degradable. [ABSTRACT FROM AUTHOR]

The stability of aerobic granular sludge (AGS) is closely related to its extracellular polymeric substances (EPS). In this study, the composition and physicochemical characteristics of EPS in AGS were determined to evaluate their roles in AGS stability. The study evaluated the influence of influent phosphorus concentration on EPS protein (PN), polysaccharide (PS) and orthophosphate content, zeta potential (ζ) and fluorescence spectrum (EEM) in loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). With higher influent phosphorus concentration, the PN, PS and orthophosphate content were higher, as was the zeta potential in TB-EPS, but it had less influence on LB-EPS. Three-dimensional, synchronous fluorescence spectroscopy and fluorescence region integral (FRI) showed that protein-like substances were the primary components of LB-EPS and TB-EPS. Phosphorus had a dynamic quenching effect on EPS at a concentration between 0 mg L-1 and 17.5 mg L-1, which is the indirect production of phosphorus by cations. An increased concentration of influent phosphorus was beneficial to AGS stability. [ABSTRACT FROM AUTHOR]

Innovations are required in urban infrastructures due to the pressing needs for mitigating climate change and prevent resource depletion. In order to address the slow pace of innovation in urban systems, this paper analyses factors involved in attempts to introduce novel sanitary systems. Today new requirements are important: sanitary systems should have an optimal energy/climate performance, with recovery of resources, and with fewer emissions. Anaerobic digestion has been suggested as an alternative to current aerobic waste water treatment processes. This paper presents an overview of attempts to introduce novel anaerobic sanitation systems for domestic sanitation. The paper identifies main factors that contributed to a premature termination of such attempts. Especially smaller scale anaerobic sanitation systems will probably not be able to compete economically with traditional sewage treatment. However, anaerobic treatment has various advantages for mitigating climate change, removing persistent chemicals, and for the transition to a circular economy. The paper concludes that loss avoidance, both in the sewage system and in the waste water treatment plants, should play a key role in determining experiments that could lead to a transition in sanitation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The presence of antibiotics seldom exerted an influence to the formation of aerobic granular sludge. • Relatively high content of protein from TB-EPS facilitated microbial adhesion and aerobic granulation. • The total antibiotics and ARB removal were up to 88.4% ± 4.5% and 89.4% ± 3.3%, respectively. • Bioadsorption and biodegradation were the dominant process for antibiotics and ARB removal. • Aerobic granular sludge is a promising technology for piggery wastewater treatment. Abstract The aim of this work was to study the responses of aerobic granulation process to antibiotics and investigate the antibiotics and antibiotic-resistant bacteria (ARB) removal and transport. Results showed that aerobic granular sludge (AGS) was dominant in the bioreactor at day 45, and the relatively high protein content from tightly bound extracellular polymeric substances (TB-EPS) facilitated aerobic granulation and maintained biomass stabilization. The protein contents in EPS and TB-EPS were positively correlated with relative hydrophobicity, thereby improving the adsorption capacity among hydrophobic particles. The chemical oxygen demand (COD), NH 3 -N, and total N removal efficiencies were 98.0%, 97.0%, and 92.4%, respectively. Five antibiotics, including kanamycin, tetracycline, ciprofloxacin, ampicillin, and erythromycin, were examined in piggery wastewater, with concentrations up to the concentration range of 29.4–44.1 µg/l, and the total antibiotics removal rate reached up to 88.4% ± 4.5%. A total of 5.2% of the total antibiotics were discharged from bioreactor, and 62.5% of the total antibiotics were degraded, and 32.3% of total antibiotics were adsorbed by aerobic granules. The presence of antibiotics rarely exhibited an influence on AGS formation, and the relatively high microbial activity of aerobic granules was beneficial to antibiotics removal. The ARB removal rate increased up to 89.4% ± 3.3%, but a large amount of ARB was enriched in aerobic granules. [ABSTRACT FROM AUTHOR]

Highlights • The stability of silage was improved in LAB-treated barley silage upon aerobic exposure. • LAB inoculant treatment regulated the effects of aerobic exposure on bacterial community in barley silage upon aerobic exposure. • The structure of fungal population was significantly modified by LAB inoculant treatment during ensiling. Abstract This study investigated the effects of lactic acid bacteria on bacterial and fungal community during the fermentation process and aerobic exposure phase of barley ensiled with preparation of lactic acid bacteria (LAB). The inoculated silages displayed higher contents of lactic acid, acetic acid, and propionic acid as well as a greater number of lactic acid bacteria during ensiling. LAB-treated silage decreased the bacterial diversity during both ensiling and aerobic exposure but increased the fungal diversity during ensiling of barley. LAB-treated silage during ensiling increased the abundance of Lactobacillus but decreased that of Weissella. After aerobic exposure, LAB-treated silage increased the abundance of Lactobacillus but decreased that of Acinetobacter. Acinetobacter , Enterococcus , Providencia , and Empedobacter were the dominant bacteria after aerobic exposure. In conclusion, LAB-treated silage enhanced the number of desirable Lactobacillus and inhibited the growth of undesirable microorganisms, such as Acinetobacter. [ABSTRACT FROM AUTHOR]

Highlights • Determination of NH 3 and GHG emissions on-site provides more value than lab tests. • Increasing ambient temperature promotes NH 3 and GHG emissions. • Improving aeration frequency decreases GHG but promotes NH 3 emissions. • In addition to CO 2 , N 2 O is a key GHG with an 11.19–43.30% CO 2 -eq contribution. Abstract This study analyzed emissions characteristics of NH 3 and greenhouse gases (i.e. N 2 O, CH 4 , and CO 2) from a municipal sewage sludge aerobic composting plant. Samples were collected during different seasons in which ambient temperatures and aeration frequencies varied. Results revealed (1) the maximum gas emissions occurred during the mesophilic phase for N 2 O (22%–56%) and CH 4 (65%–95%), and in the thermophilic phase for NH 3 (84%–86%) and CO 2 (65%–74%); (2) raising ambient temperatures promoted emissions of NH 3 and greenhouse gases, while improved aeration frequency increased NH 3 but decreased greenhouse gas emissions; (3) CO 2 and N 2 O were found to be the key greenhouse gases emitted during aerobic composting according to assessment of the CO 2 equivalent. The results obtained from this study suggest that adjusting ambient temperature to −3 to 5 °C and aeration frequency in composting workshops can be useful approaches for the reduction of NH 3 and greenhouse gas emissions from municipal sewage sludge composting plants. [ABSTRACT FROM AUTHOR]

Highlights • AnMBR needs further research to optimize process efficiency. • Modelling can provide insight into the factors playing a key role in AnMBR. • Process models still face a long path to adaptation in practice. • Better understanding of fouling mechanisms in AnMBRs is required. • Control strategies can be further optimized from mechanistic knowledge of fouling. Abstract The use of anaerobic membrane bioreactor technology (AnMBR) is rapidly expanding. However, depending on the application, AnMBR design and operation is not fully mature, and needs further research to optimize process efficiency and enhance applicability. This paper reviews state-of-the-art of AnMBR focusing on modelling and control aspects. Quantitative environmental and economic evaluation has demonstrated substantial advantages in application of AnMBR to domestic wastewater treatment, but detailed modelling is less mature. While anaerobic process modelling is generally mature, more work is needed on integrated models which include coupling between membrane performance (including fouling) and the biological process. This should include microbial factors, which are important to generation of specific foulants such as soluble and particulate inert organics. Mature and well-established control tools, including better feedback control strategies are also required for both the process, and for fouling control. [ABSTRACT FROM AUTHOR]

Highlights • Parameters of AGS formation were reviewed, and reference values were proposed. • Parameters of AGS maintenance were reviewed, and reference values were proposed. • The main metabolic pathways for removal of some compounds by AGS were discussed. • Microbial groups present in AGS and their respective functions were discussed. • The favoring strategies for AOB, NOB, PAO and GAO in AGS were proposed. Abstract Aerobic granular sludge (AGS) has been the focus of many investigations, and the main parameters responsible for AGS formation are hydrodynamic shear force, short periods and feast-famine cycles. However, some other parameters are associated with AGS maintenance after long periods of operation. This review evaluates the parameters responsible for AGS formation and maintenance and some reference values are proposed. In addition, some discussions are addressed about the main metabolic pathways that AGS uses for the removal of some compounds, such as nutrients, organic matter, dyes, recalcitrant compounds, among others. Finally, the main microbial groups present in the AGS and their respective functions are discussed. It is also highlighted that many parameters that are taken as reference currently for AGS cultivation and maintenance can be optimized for energy savings, implementation costs, among others, as well as a greater recovery of resources during wastewater treatment, within the scope of the biorefinery concept. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Created a nitritation-denitritation/denitrification-nitrification. • Spontaneous recovery of permeability can be achieved. • The aerobic granular sludge (AGS) was cultivated successfully. • The deploying of AOB and NOB was reached by the two-stage system. Abstract A novel pilot gravity-driven anoxic/oxic fed-batch membrane bioreactor (AFMBR) was developed to treat real domestic wastewater. In this process, the anoxic and oxic stages created favorable conditions for stable and continuous nitritation-denitritation/denitrification-nitrification links without adding external carbon source. Excellent removals of organic carbon/nitrogen (NH 4 +-N: 71–97%, COD: 78–96%, UV 254 : 70–95%, TN: 20–60%) and spontaneous permeability recovery were achieved simultaneously. It was assessed at micro levels by characterizing sludge particle morphologies, microbiota functional evolutions, fouling layer properties and energy consumptions. It was demonstrated that the aerobic granular sludge (AGS) was cultivated successfully. Notable differences of microbial diversity were observed in different regions of AFMBR. The SEM and AFM spectra suggested the loose cake layers can shed automatically due to low pressure and continue flushing. The energy consumption in AFMBR was around 0.042 kWh/m3, far lower than that of conventional MBR. Overall, the AFMBR has a potential on improvement of domestic wastewater treatment. [ABSTRACT FROM AUTHOR]

A range of thermal pretreatment conditions were used to evaluate the impact of high pressure thermal hydrolysis on the biodegradability of waste activated sludge (WAS) under aerobic and anaerobic conditions. It was found that pretreatment did not increase the overall extent to which WAS could be aerobically biodegraded. Thermal pretreatment transformed the biodegradable fraction of WAS (XH) to readily biodegradable chemical oxygen demand (COD) (SB) (16.5-34.6%) and slowly biodegradable COD (XB) (45.8-63.6%). The impact of pretreatment temperature and duration on WAS COD fractionation did not follow a consistent pattern as changes in COD solubilization did not correspond to the observed generation of SB through pretreatment. The pretreated WAS (PWAS) COD fractionations determined from aerobic respirometrywere employed in anaerobic modeling and it was concluded that the aerobic and anaerobic biodegradability of PWAS differed. It was found that thermal pretreatment resulted in as much as 50% of the endogenous decay products becoming biodegradable in anaerobic digestion. Overall, it was concluded that the COD fractionation that was developed based upon the aerobic respirometry was valid. However, it was necessary to implement a first-order decay process that reflected changes in the anaerobic biodegradability of the endogenous products through pretreatment. [ABSTRACT FROM AUTHOR]

To develop a better understanding for fixed biomass processes, the development of a nitrifying bacterial biofilm, as well as the performance of treatment during modifications to operational conditions of a full-scale submerged biological filter were examined. The development of the nitrifying biofilm was investigated at four depth levels (1, 2, 4 and 5 feet). The result of bacterial subpopulations analyzed by qPCR relative to the physico-chemical parameters of the wastewater during the various tests (sustained aeration, modified backwash parameters and inflow restriction) revealed an increase of the relative presence of nitrifying microorganisms throughout the biofilm (especially for nitrite oxidizing bacteria (NOB)), but this was not necessarily accompanied by a better nitrification rate. The highest observed nitrification rate was 49% of removal in the test cell during backwashing conditions, whereas the relative ammonia oxidizing bacteria (AOB) population was 0.032% and NOB was 0.008% of the total biomass collected. The highest percentage of nitrifying bacteria observed (0.034% AOB and 0.18% NOB) resulted in a nitrification rate of 21%. The treatment of organic matter determined by measuring the chemical and biochemical oxygen demand (COD, CBOD5) was improved. [ABSTRACT FROM AUTHOR]

Simultaneous nitrification, denitrification and phosphorus removal (SNDPR) using aerobic granules is a promising approach in water treatment. The present work investigated the effects of influent carbon to nitrogen (N) ratios (20, 10, and 4) on the SNDPR performance in aerobic granular sequencing batch reactors (AGSBR) under high aeration rate. Results revealed that granules remained long-term stability when the DO concentration was 7–8 mg/L. With the decline of COD/N ratios, the denitrification efficiency was reduced due to the accumulation of nitrate, although the removal of COD and TP remained stable with good efficiency. Rising concentration of ammonia N led to the increase of PN/PS ratio of EPS as well as the protein types according to the results of 3D-EEM fluorescence spectroscopy. MiSeq pyrosequencing technology indicated that the decreasing ratio of COD/N under high DO concentration contributed to accumulation of GAOs and DNPAOs rather than PAOs. [ABSTRACT FROM AUTHOR]

Adsorption is an important step during the migration of ammonium from the aqueous phase to biomass in biological nitrogen removal processes. A deeper understanding of the adsorption mechanisms is encouraged in constructing nitrogen conversion models. In this study, the ammonium adsorption in aerobic granular sludge was investigated at different conditions. Analysis of kinetic data indicated that ammonium adsorption was a fast process and followed pseudo-second-order kinetics (adsorption rate constant k2 was between 0.031 and 0.065 g/(mg ⋅ min)). The maximum adsorption capacity and half saturation constant KL in the Langmuir isotherm model were 4.95 mgNH4+-N/g total suspended solids and 0.0126 L/mg, respectively. Effects of environmental conditions such as temperature, pH and competitive cations were also estimated. The optimum pH was 7 and the effects of competitive cations were in the order Ca2+ > Mg2+ > K+ > Na+. Values of thermodynamic parameters (ΔHΘ = -14.697 kJ/mol, ΔSΘ = -6.65 J/(mol ⋅ K)) indicated that the adsorption process was spontaneous and exothermic. Desorption tests showed that the process was reversible and low temperature had a negative effect on ammonium desorption. These findings could be useful for completing the mathematical model of the nitrogen removal process in bioreactors. [ABSTRACT FROM AUTHOR]

Abstract In the present work, catalytic wet air oxidation (WAO) technique was applied to biomethanated spent wash from a local sugar factory. This wash water exhibited high biological oxygen demand (BOD 5 = 8100 mg/L) and chemical oxygen demand (COD = 40,000 mg/L). The objectives of oxidative pre-treatment were two-fold, viz. efficient treatment of wash water and enhanced biogas recovery. For the catalytic oxidation process, two iron-based heterogeneous catalysts were employed, viz. Fe 2 O 3 and Fe/C. To synthesize the Fe/C catalyst, activated carbon (AC) support was modified either by thermal treatment or chemical treatment with nitric acid; accordingly, the catalyst was named as Fe/AC-T or Fe/AC-N. In a batch slurry reactor, catalyst performance was investigated at T = 175 °C, P O 2 = 0.69 MPa and ω = 33 mg/L (here, T, P O 2 and ω denote temperature, oxygen partial pressure and catalyst loading) for 1 h. Based on the conversions of COD and total organic carbon (TOC) and the improvement in biodegradability index (BI), it was found that the activity of the catalysts reduced in the order: Fe/AC-N > Fe/AC-T > Fe 2 O 3. The results were more encouraging (COD conversion = 87%, color reduction = 88% and BI value = 0.71) when carbon adsorption (5% w/v) followed WAO over Fe/AC-N. Clearly, our novel hybrid process for pre-treatment, viz. wet oxidation-carbon adsorption showed potential. Post biomethanation, around 1.2 Nm3 biogas (CH 4 72%) was formed per cubic meter of the wastewater; without pre-treatment by catalytic WAO and carbon adsorption, the yield of biogas (CH 4 11%) was just 1 Nm3 for every cubic meter of wastewater. After a last aerobic treatment step, 97% COD was removed and BI value was 0.84. Finally, a kinetic model was proposed to describe kinetics of COD reduction. In this way, a promising method was suggested for treating a complex wastewater. Graphical abstract Image 1 Highlights • Pre-treatment of spent wash by wet oxidation-carbon adsorption was suggested. • Carbon-supported iron catalyst was promising for wet oxidation of spent wash. • Proposed pre-treatment generated more biogas and made aerobic treatment easier. • Two-step power law type kinetic model for COD destruction was proposed. [ABSTRACT FROM AUTHOR]

Highlights • Effects of alkaline treatments of return sludge on sludge reduction were studied. • Alkaline treatments at pH 10 and 11 led to sludge reduction of 18.8%–31.7%. • Alkaline treatment at pH 12 led the system to break down. • Alkaline treatment at pH 10 did not affect removals of COD and NH 4 +-N and SVI. • Alkaline treatments at pH 10 and 11 increased SOUR of aerobic activated sludge. Abstract Three alkaline treatments (pH 10, 11, and 12 for 1 h) were used to treat return sludge alone to reduce sludge production in laboratory-scale anaerobic–anoxic–oxic processes. After 99 days of operation, alkaline treatments at pH 10 and 11 led to accumulative excess sludge production and sludge yield reduction of 18.8%–31.7% and 14.7%–27.8%, respectively. However, alkaline treatment at pH 12 led to system breakdown because of sludge bulking. The alkaline treatment at pH 10 did not affect the chemical oxygen demand and NH 4 +-N removals of the system and sludge volume index (SVI) of aerobic activated sludge. However, alkaline treatments at pH 11 and 12 obviously deteriorated the wastewater treatment efficiencies and sludge SVI. Although the three treatments increased the effluent pH by 0.08 to 0.38, the effluent pH of three systems were all lower than 9.00. The treatments at pH 10 and 11 increased the specific oxygen uptake rate of activated sludge, whereas the treatment at pH 12 decreased this rate. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The impacts of tetracycline on the wastewater treatment system were examined. • Exposure of 5 mg l−1 tetracycline decreased ammonia nitrogen removals. • Exposure of 5 mg l−1 tetracycline accelerated the sludge bulking. • An important nitrifier, Nitrospira , was inhibited under exposure of tetracycline. • The sludge bulking bacteria, Sphaerotilus , was fostered under tetracycline exposure. Abstract The occurrence of various antibiotics in wastewater treatment systems continues to arouse extensive attention. However, the effects of low concentration of antibiotics on wastewater treatment performance and the related functional bacteria, especially under long-term operation, remain largely unknown. In this study, a lab-scale anaerobic-aerobic system was established to evaluate the impacts of 5 mg l−1 tetracycline on the performance of a lab-scale wastewater treatment system and the abundance of the related functional bacteria. The results indicated that Tc exposure had little effect (p > 0.05) on the efficiency of COD removal during the whole period of 200 days, but significantly decreased ammonia removal (p < 0.05) and accelerated sludge bulking deterioration. Although the core bacterial communities and the abundance of amoA genes in the activated sludge were not affected, the growth of Nitrospira was inhibited (p < 0.05), and Sphaerotilus was promoted by tetracycline exposure. The results of this study provide important references for the maintenance of wastewater treatment systems. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Aeration pattern is of prior importance compared to aeration intensity during granulation. • Gas distributor characteristics greatly influence on prevailing aeration pattern. • Gas holdup is an easy-to-measure controlling parameter for scale-up of granular reactors. Abstract This study investigates the influence of aeration pattern and gas bubble distribution on aerobic granulation in pilot bubble columns and advances the understanding on crucial factors to be considered during scale-up. Experiments were conducted in a pilot scale bubble column of 22-L capacity. A laboratory-scale bubble column of 5-L capacity, which could achieve granulation in a short time, was used as the control reactor. The pilot reactor was operated with optimal operational conditions evaluated for the control reactor, but the granulation was initially inhibited; improper aeration pattern was found as the most significant factor in precluding granulation. Aerobic granulation in the pilot-scale reactor was achieved upon modifying the gas distributor design. The effect of gas distributor characteristics (i.e. , pore size, free area φ , and relative surface area of the gas distributor to the cross-section of the column R) on the aeration pattern has been thoroughly discussed. A scale-up ratio (S) for the gas distributor has been proposed. Reliability of aeration intensity in terms of superficial air velocity u sg , which has been commonly used as an indicator of prevailing hydrodynamics and shear stress in lab-scale granular bubble columns, has been discussed; it was demonstrated that u sg could not realistically represent the aforementioned conditions in a larger module. Instead, it was suggested that a greater attention should be paid to bubble size and bubble ascending velocity and thus to the subsequent aeration pattern. Gas holdup has been eventually introduced as a crucial and easy-to-measure controlling parameter for the scale-up of granularreactors. [ABSTRACT FROM AUTHOR]

Recently, studies have been carried out on an implementation of aerobic granular sludge (AGS) technology in fullscale wastewater treatment plants. The aim of the work was to evaluate the effectiveness of organic, phosphorus and nitrogen compounds removal from municipal wastewater and to characterize the biomass in a wastewater treatment plant upgraded from the activated sludge to AGS technology. In the upgraded facility, granulation was obtained quickly and it was observed that the granule morphology depended of the temperature. In the granular biomass harvested at moderate temperatures in the reactor (15°C), the granules with diameters in the range from 125 to 500 μm constituted the largest share (about 60%), while the second-largest biomass fraction comprised the granules with diameters over 1 mm (25%). The analysis of granule diameters carried out in winter (the temperature in the reactor equaled 8°C) showed a decrease in the share of the largest granules and predominance of the granules with diameters in the range from 90 to 355 μm (about 75%). Upgrading the municipal wastewater treatment plant from activated sludge to aerobic granular sludge significantly improved the settling properties of the biomass and efficiency of wastewater treatment. The average efficiency chemical oxygen demand (COD) and phosphorus removal increased by about 10% and 20%, respectively, while ammonium nitrogen was completely oxidized, regardless of the season. After modernization, the concentration of nitrates in the effluent increased significantly to about 3-6 mg/L. The results of the study show that it is possible to effectively upgrade the existing facilities to aerobic granular sludge technology; it was also proven that this technology is an excellent alternative to a conventional activated sludge. [ABSTRACT FROM AUTHOR]

A mesophilic anaerobic digester, followed by a psychrophilic aerobic post-treatment, was used to treat food waste (FW) with different proportions of fruit and vegetable waste (FVW). Two types of FW were used: low fruit and vegetable mix (LFV, with 56.5% of FVW) and high fruit and vegetable mix (HFV, with 78.3% of FVW). The anaerobic digester fed with LFV failed at an organic loading rate of 1.6 g VS.L-1.d-1 (volatile fatty acid (VFA) = 6000 mg.L-1) due to high ammonia (reaching 3000 mg.L-1). It was shown that, in an unstable anaerobic environment, ammonia is highly correlated (r2 = 0.77) with VFA and is negatively correlated with volatile solids, total solids, and chemical oxygen demand (COD) removal rates (r2 = 0.88, r2 = 0.71, and r2 = 0.91, respectively). In contrast, the anaerobic digester fed with HFV exhibited a stable performance (VFA = 1243 mg.L-1), with limited ammonia accumulation (940 mg.L-1). Methane generation was affected by the FVW content and reached 531 ml CH4.g VS-1 (CH4 = 52%) with LFV feed and 478 ml CH4.g VS-1 (CH4 = 57.4%) with HFV. The overall TS, VS and COD removal rates (all ranging between 94% and 97%), were closely similar for LFV and HFV. Accordingly, the aerobic post-treatment seems to compensate for the reduced performance of the disturbed anaerobic system fed with LFV. [ABSTRACT FROM AUTHOR]

The system performance, economic cost and environmental impact of a full-scale anaerobic/anoxic/ aerobic/membrane bioreactor (3AMBR) combined with the ozonation process were evaluated. The 3AMBR/ozonation process removed biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids, NH4-N and total phosphorus efficiently, with removal percentages above 94%, while the total nitrogen removal percentage was only 70%. The multiple linear regression analysis showed that hydraulic retention time (HRT) had a significant effect on nitrogen removal. A low HRT benefited nitrogen removal. Ferrous sulfate dosage close to the optimal value and a high mixed liquid suspended solid could enhance the phosphorus removal. The electricity cost accounted for 88% of the total economic costs. Greenhouse gas (GHG) emissions from the BOD oxidation and endogenous decay accounted for more than 50% of total emissions. The second largest GHG emission source was electricity consumption, accounting for 41%. The key to reduce the eutrophication was to enhance nitrogen removal. The composite cost of the 3AMBR/ozonation process was 251 CNY/t CODeq removed, among which economic cost accounted for 82.5%, while environmental impact cost accounted for a small proportion. [ABSTRACT FROM AUTHOR]

The presence of unused dyes and dye degradation intermediates in the textile industry wastewaters is the major challenge in its treatment. A wide range of treatments including various physicochemical processes are used for this wastewater. Incomplete dye degradation results in hazardous colorless aromatic amine intermediates that are teratogenic in nature. A synergistic plant-microbe system operated in a sequential anaerobic-aerobic mode was evaluated for the complete degradation of a model azo dye methyl red under laboratory conditions. The degradation of methyl red and its break down products 2-aminobenzoic acid and N,N-dimethyl-p-phenylenediamine were analysed by HPLC, FTIR and GC–MS. The vetiver-microbe system had shown enhanced dye degradation. The dye decolourization percentage achieved for integrated plant-microbe treatment system (T) after anaerobic condition was 53.5 ± 6.2% and aerobic condition was 92 ± 3.4%. The removal efficiency of the intermediates 2-ABA and DMPD was found to be 89.79% in the integrated plant-microbe treatment system. The plant-microbe system was most effective in the removal of toxic aromatic amine as seen by lesser phytotoxicity for seed germination and teratogenicity in case of zebrafish development in the treated water. [ABSTRACT FROM AUTHOR]

Energy recovery from nitrogen via nitrous oxide by applying e.g., the Coupled Aerobic-anoxic Nitrous Decomposition Operation (CANDO), is a potential key to more sustainable and energy-efficient wastewater treatment facilities. In this study, laboratory-scale investigations were conducted for the second stage of a continuously operated CANDO process over 84 cycles to test and validate the oxidation reduction potential (ORP) as operational control variable. The ORP was investigated to optimize effluent nitrite (NO 2 − ) concentrations, nitrous oxide (N 2 O) yields and overall process conditions under real feed-stream conditions. Characteristic deviations for stable operational conditions, underload and overload could be derived based on representative cycles. The results revealed that continuously increasing ORP deviations are correlated to the abundance of nitrite in anoxic reaction periods and that the depletion of nitrite and nitrous oxide correlates with switching from a positive to negative ORP gradient. These observations were supported by investigating the dynamics of relevant process parameters of a single cycle. Ultimately, the reactor was successfully operated under dynamic conditions i.e., different chemical oxygen demand to nitrite ratios (COD/N) ratios, and automatically controlled by applying an ORP gradient of −1 mV/min over 20 min as termination criterion for anoxic reaction periods. This operation resulted in stable and reliable NO 2 − elimination. Additionally, previous observations concerning the necessity of a COD/N ratio of 4 could be confirmed concerning optimal N 2 O yields. A COD/N ratio of 5 compromised the N 2 O yield to a higher nitrogen removal rate. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the performance and microbial community structure of a polar Arctic Circle aerobic granular sludge (AGS) system operating at low temperature. Thus, an AGS bioreactor was operated at 7, 5 and 3 °C of temperature using a cold-adapted sludge from Lapland. At 5 °C, it yielded acceptable conversion rates, in terms of nitrogen, phosphorous, and organic matter. However, under 3 °C a negligible nitrogen and phosphorous removal performance was observed. Below 5 °C, scanning electron microscopy studies showed a wispy, non-dense and irregular granular structure with a strong outgrowth of filamentous. Moreover, Illumina next-generation sequencing showed a heterogeneous microbial population where SM1K20 ( Archaea ), Trichosporon domesticum ( Fungus ), and Zooglea , Arcobacte r and Acinetobacte r ( Bacteria ) were the dominant phylotypes. Our study suggests that AGS technologies inoculated with North Pole sludge could be operated, in cold regions for a period longer than 3 months (winter season) under 5 °C of water temperature. [ABSTRACT FROM AUTHOR]

A new excess phosphate uptaking in an anoxic-aerobic sequencing batch reactor (SBR) using starch as sole carbon source that was different from the traditional biological phosphorus removal in anaerobic-aerobic alternation condition was confirmed and reported previously. To reveal its mechanism and biochemical pathway of metabolism, this study was conducted. Nuclear magnetic resonance (NMR) technique was applied to trace the carbon metabolism in the SBR applied by supplying 13 C label starch. Results show that the phosphorus removal reached 80% without any P release during the whole process. The sludge had a very lower accumulation of polyhydroxyalkanoates (PHAs) but a higher accumulation of glycogen. The metabolic pathway of glycogn synthesis and phosphorus removal was proposed that during the anoxic phase, the starch was hydrolyzed and then converted to lactic acid by lactic acid producing organism (LPO). Adenosine triphosphate (ATP) was generated from the lactic acid formation, and used for polyphosphate (poly-P) synthesis. In the meantime, lactic acid was used to synthesize glycogen by phosphate accumulating organisms (PAOs). In the aerobic stage, PAOs oxidized glycogen to release energy for cell growth and its maintenance, as well as phosphate uptake and poly-P synthesis. The LPO performed the majority of the P removal in the SBR during the anoxic stage. This study improves our understanding to how phosphorus removed in the anoxic-aerobic system. [ABSTRACT FROM AUTHOR]

Three cylindrical vertical flow (VF) (1st stage) and three horizontal flow (HF) vermifilters (2nd stage) were designed and planted with Canna indica to study the effect of HLR. The vermifilters were loaded (to VF) with synthetic dairy wastewater at three HLRs of 0.3, 0.6 and 0.9 m d −1 and operated for 100 days. Removal rate constants were higher at HLR 0.6 m d −1 and the value of K BOD5 , K COD , K NH4+-N , K TN , K TP (for VF + HF unit) were 0.51, 0.41, 0.32, 0.23, 0.26, respectively. Efficiency of VF reactor were higher than HF reactor in case of all types of pollutants. The average removal of BOD 5 was found to be 90.43% at HLR 0.3 m d −1 and 85.75% at HLR 0.6 m d −1 , while for COD it was found to be 85.59% and 79.64%, respectively. In the present study, the overall theoretical oxygen transfer rate (OTR) for HLR 0.3, 0.6 and 0.9 m d −1 (VF + HF unit) were 36, 92 and 195.6 g m −2  d −1 , respectively. The OTR value for HF reactor was very less. The present value is much higher than other studies and it may be due to earthworm respiration and their burrowing and tunnelling activities. The percentage increase of earthworm number in all VF reactors were in the range of 28.3–31.5 and in HF reactor in the range of 19.1–26.2. [ABSTRACT FROM AUTHOR]

Energy, water, and waste systems analyzed at a nexus level are important to move toward more sustainable cities. In this paper, the "resilience.io" platform is developed and applied to emphasize on waste-to-energy pathways, along with the water and energy sectors, aiming to develop waste treatment capacity and energy recovery with the lowest economic and environmental cost. Three categories of waste including wastewater (WW), municipal solid waste (MSW), and agriculture waste are tested as the feedstock for thermochemical treatment via incineration, gasification, or pyrolysis for combined heat and power generation, or biological treatment such as anaerobic digestion (AD) and aerobic treatment. A case study is presented for Ghana in sub-Saharan Africa, considering a combination of waste treatment technologies and infrastructure, depending on local characteristics for supply and demand. The results indicate that the biogas generated from waste treatment turns out to be a promising renewable energy source in the analyzed region, while more distributed energy resources can be integrated. A series of scenarios including the business-as-usual, base case, naturally constrained, policy interventions, and environmental and climate change impacts demonstrate how simulation with optimization models can provide new insights in the design of sustainable value chains, with particular emphasis on whole-system analysis and integration. [ABSTRACT FROM AUTHOR]