Effluent Water Research Articles

Drug-degrading bacteria isolated from the effluent water of a sewage plant.

Endocrine disruptors are potential environmental contaminants that can cause toxicity in aquatic ecosystems, so the Water Framework Directive has established limits for these compounds. During our research, 41 bacterial strains were isolated and identified from sewage effluent and tested for their degradation capacities for bisphenol A, 17β-estradiol, and nonylphenol. All the isolated bacteria belonged to the Gammaproteobacteria class of Pseudomonadota phylum (members of Citrobacter, Enterobacter, Escherichia, Klebsiella, Kluyvera, Leclercia, Raoultella, Shigella. Acinetobacter, Aeromonas, and Pseudomonas genera). During the experiments, only strains HF17, HF18 (Pseudomonas aeruginosa), and HF31 (Citrobacter freundii) were unable to grow on these compounds, all other bacterial strains could grow in the presence of the investigated endocrine disruptors. Based on the genomic analysis of the type strains, a set of genes involving aromatic compound degradation was detected, among the peripheral metabolic pathways, the quinate and benzoate degradation pathways proved to be widespread, among the central aromatic intermediates metabolism, the catechol branch of the beta-ketoadipate pathway was the most dominant. Pseudomonas fulva HF16 strain could utilize the investigated endocrine disruptors: bisphenol A by 34%, 17β-estradiol by 52%, and nonylphenol by 54%.

Environmental risk assessment of pharmaceuticals in wastewaters and reclaimed water from catalan main river basins

Aquatic pollution from pharmaceuticals is a growing environmental concern globally, particularly in Catalonia's primary water bodies, the Llobregat and Besòs rivers. This study investigates pharmaceutical residues in reclaimed water effluents from the Llobregat River and a wastewater treatment plant (WWTP) in the Besòs River, critical contributors to the region's water resources. Employing LC-MS/MS, 85 pharmaceutical residues were monitored, revealing elevated concentrations of tramadol, losartan, and gemfibrozil, commonly prescribed drugs in Catalonia. Surprisingly, downstream concentrations exceeded upstream levels significantly, indicating the adverse impact of reclaimed water on water quality. Furthermore, evaluation of WWTP efficiency displayed varying removal rates, from 10 % to 99.8 %, highlighting treatment inadequacies for certain compounds. Predictive environmental concentrations (PECs) aligned closely with measured values, affirming the utility of predictive models in early-stage research. Risk assessment via the risk quotient (RQ) method identified atorvastatin and chlorpromazine as surpassing toxicity thresholds.This study underscores the urgent need to address pharmaceutical contamination in urban rivers and reclaimed waters in Catalonia. By highlighting treatment inefficacies and potential ecological risks, it contributes to the development of sustainable water management strategies and environmental conservation efforts in the region. Efforts should focus on continuously monitoring specific compounds, evaluating their individual toxicity, and implementing appropriate remediation techniques in WWTPs to safeguard water quality and aquatic ecosystems.

Evaluation of Water Quality Indexes and Heavy Metal Pollution Indexes of Different Industrial Effluents and Karnaphuli River Water in Chattogram, Bangladesh

ABSTRACTThe study evaluated the water quality index (WQI) and heavy metal pollution index (HPI) of different industrial effluent and surface water from various sites of the Karnaphuli River, based on the weighted arithmetic index method. The samples were collected from 20 different industries, including textile dyeing, textile washing, oil processing, chemicals, and tannery, and 17 stations of the Karnaphuli River, from the Kalurghat Bridge to the estuary where the river meets with the Bay of Bengal. This study was carried out in the dry season of the 2021–2022 fiscal year. Six physicochemical parameters, namely pH, biochemical oxygen demand, chemical oxygen demand, total dissolved solids, electrical conductivity, and hardness, were taken for the determination of the WQI, and concentration of heavy metals (Pb, Fe, Cd, Cu, Cr, Mn, and Ni) were considered for the calculation of the HPI. Both indexes were calculated against the Bangladesh Standard (denoted by subscript a) and WHO standards (denoted by subscript b). The water quality indexes WQIa and WQIb for industrial effluent ranged from 11.66 to 176.77 and 44.45 to 9703.99, respectively. Samples namely TD‐5, TD‐7, TD‐8, TD‐9, TD‐10, OS‐1, and C‐1 showed excessively high WQI value. On the other hand, the HPIa and HPIb of industrial effluent varied from 43.6 to 167,785.3 and 0.34 to 18,412.3, respectively. Furthermore, oil processing and chemical effluents showed noticeably higher HPI values than other industrial samples. Both WQI and HPI values indicated a serious pollution load in most experimental samples. No river water sample showed a WQI value below 100, denoting it was unfit for consumption. The water quality indexes WQIa and WQIb for river water samples ranged from 1275.40 to 29,405.77 and 131.20 to 5860.99, respectively. According to the Bangladesh Standard, the river water samples were moderately to highly polluted by metal. The highest HPI value for the river water sample was 7965, denoting extreme metal pollution. The investigation revealed that most industrial effluents and Karnaphuli River water samples contained significant pollution load. Therefore, effective measures must be adopted immediately for future sustainability to cope with this contamination. The results emphasize the immediate requirement for strict regulations and advanced water treatment technologies to reduce contamination risks in the Karnaphuli River. Prompt action by authorities is essential to safeguard the river, prevent ongoing ecological damage, and address metal accumulation in fish affecting the food chain. Public awareness and legislative measures are vital for ecosystem preservation.

Efficiency improvement of wastewater treatment plants under the background of “double carbon”: a case study in Jiujiang city, China

Wastewater treatment plants (WWTPs) play a crucial role in modern urban water environmental protection. However, they face challenges related to high operational costs and carbon emissions. This study focused on addressing these issues through an analysis of four urban WWTPs in Jiujiang city, China. The study involved comparing the size and processes of the plants, evaluating influent and effluent water quality, assessing energy consumption and chemical usage, and calculating both direct and indirect carbon emissions. The results demonstrated that the high operational costs and increased carbon emissions in these WWTPs were primarily attributed to low hydraulic loadings, low influent concentration, and high energy and chemical consumption. In response, three targeted scenarios were proposed to enhance the efficiency of the WWTPs and reduce carbon emissions. These scenarios involved adjusting the amount of wastewater imported into the WWTPs to meet the designed capacity, optimizing operating costs, or combining both approaches. Among the scenarios, Scenario 3 emerged as the most effective in terms of improving efficiency and reducing carbon emissions. The operational costs for WWTPs could be reduced in the range of 0.42–1.04 RMB/m3, representing a reduction rate of 35%–57%. Additionally, carbon emissions could be lowered from 15.02 to 598.85 gCO2e/m3, corresponding to a reduction of 2.91%–41.38%. Although Scenario 2 exhibited a lower carbon emission reduction of 14.8–316.33 gCO2e/m3, it was identified as the most feasible and easily implementable high-efficiency solution at present, with a reduction in operational costs ranging from 0.43 to 1.31 RMB/m3. To achieve zero energy consumption and zero carbon emissions in wastewater treatment in the future, it is recommended to undertake additional measures, such as enhancing dosing system accuracy, implementing tail gas collection, adopting photovoltaic power generation, implementing carbon sequestration techniques, and exploring wastewater heat source recycling. These findings provide valuable insights for optimizing the operational efficiency of urban WWTPs, reducing carbon emissions, and promoting sustainable wastewater treatment practices in Jiujiang city, China.

Efficient PAHs removal and CO2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production

Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L−1 d−1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg−1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.

Treated wastewater: A hotspot for multidrug- and colistin-resistant Klebsiella pneumoniae

Wastewater treatment plants are hotspots for the release of antimicrobial resistant pathogenic bacteria into aquatic ecosystems, significantly contributing to the cycle of antimicrobial resistance. Special attention should be paid to antimicrobial resistant ESKAPE bacteria, which have been identified as high-priority targets for control measures. Among them, Klebsiella pneumoniae is particularly noteworthy. In this study, we collected wastewater samples from the inlet, sedimentation tank, and effluent water of a wastewater treatment plant in June, July, October, and November of 2018. We detected and characterized 42 K. pneumoniae strains using whole genome sequencing (15 from the inlet, 8 from the sedimentation tank, and 19 from the effluent). Additionally, the strains were tested for their antimicrobial resistance phenotype. Using whole genome sequencing no distinct patterns were observed in terms of their genetic profiles. All strains were resistant to tetracycline, meanwhile 60%, 47%, and 37.5% of strains isolated from the inlet, sedimentation tank, and effluent, respectively, were multidrug resistant. Some of the multidrug resistant isolates were also resistant to colistin, and nearly all tested positive for the eptB and arnT genes, which are associated with polymyxin resistance. Various antimicrobial resistance genes were linked to mobile genetic elements, and they did not correlate with detected virulence groups or defense systems. Overall, our results, although not quantitative, highlight that multidrug resistant K. pneumoniae strains, including those resistant to colistin and genetically unrelated, being discharged into aquatic ecosystems from wastewater treatment plants. This suggests the necessity of monitoring aimed at genetically characterizing these pathogenic bacteria.

Anchoring N and Co species on the aluminum-graphite surface to enhance oxygen activation for the degradation of tetracycline at neutral conditions

Molecular oxygen (O2) activation for reactive species (RSs) production has recently received increasing interest. Reported herein is a novel O2 activator (Al-Gr-N/Co), synthesized by anchoring N and Co species on the aluminum-graphite (Al-Gr) surface, that could achieve efficient degradation of tetracycline (TC) by activating O2 in air purging water. RSs, including HO•, O2•− and 1O2, could be generated in the Al-Gr-N/Co/Air process, achieving 97.8 % of TC degradation at pH 7. This degraded TC can be attributed to the oxidation by 1O2 and HO•; direct adsorption by Al-Gr-N/Co also contributed to the TC degradation. The N species promoted the H2O2 production during O2 activation by Al-Gr-N/Co; these produced H2O2 could be further converted to RSs by Co and N species. Demethylation, hydroxylation and dehydration reactions were proposed as the oxidation pathways of TC by Al-Gr-N/Co/Air. TOC result suggests that TC and the oxidized intermediates could be adsorbed by Al-Gr-N/Co or converted to inorganic compounds. Negligible amount of the dissolved metal ions (<0.44 mg/L) was observed after reaction. Highly efficient removal of TC (>82.2 %) in lake water, tap water and MBR secondary effluents suggested that the Al-Gr-N/Co/Air process could be potentially applied in real water systems.

Bacterial microbiome dynamics in commercial integrated aquaculture systems growing Ulva in abalone effluent water

In South Africa, the green seaweed Ulva lacinulata is grown in land-based integrated multi-trophic aquaculture (IMTA) farms with the abalone Haliotis midae. The Ulva serves as a biofilter and the co-produced Ulva is often used as feed for the abalone. To better understand the potential benefits and risks associated with this practice, this study characterised the bacterial microbiome associated with the seawater and Ulva raceways receiving abalone effluent (IMTA system) and compared this to Ulva tanks supplied with fertilised seawater (non-IMTA; control). Ulva samples were collected from each Ulva system, and water samples were collected at the inlet and outlet of each system. Bacterial communities were assessed using a culture-based approach and next-generation sequencing (NGS) of the V3-V4 16S rDNA region. It was observed that Ulva has the potential to reduce the bacterial load of abalone effluent, with the total number of potential culturable Vibrio species declining from 150×103 cells mL-1 in the inlet to 37×103 cells mL-1 in the outlet of the Ulva system. The NGS dataset supported these findings, with a reduction observed in Vibrio and Pseudoalteromonas from the inlet to outlet samples. A lower number of genera (p < 0.05) were observed on Ulva when compared with water samples, indicating that Ulva has a beneficial, modulatory effect on bacteria. These findings contribute towards the growing body of evidence for the benefits of seaweeds in IMTA and addresses the biosecurity concerns of abalone farmers wishing to improve the circularity of their farming activities by incorporating seaweeds.

One Health Threat of Treated Wastewater Discharge in Urban Ohio Rivers: Implications for Surface Water and Fish Gut Microbiome and Resistome.

Wastewater treatment plants (WWTPs) are thought to be a major disseminating source of antibiotic resistance (AR) to the environment, establishing a crucial connection between human and environmental resistome. The objectives of this study were to determine how wastewater effluents impact microbiome and resistome of freshwater and fish, and identify potential AR-carrying clinically relevant pathogens in these matrices. We analyzed wastewater influent and effluent from four WWTPs in three metropolitan areas of Ohio, USA via shotgun metagenomic sequencing. We also sequenced river water and fish guts from three reaches (upstream, at the WWTP outfall, and downstream). Notably, we observed a decline in microbiome diversity and AR gene abundance from wastewater to the receiving river. We also found significant differences by reach and trophic level (diet) in beta-diversity of the fish gut microbiomes. SourceTracker revealed that 0.443 and 0.248 more of the of the fish gut microbiome was sourced from wastewater effluent in fish from the outfall and downstream locations, respectively, compared to upstream fish. Additionally, AR bacteria of public health concern were annotated in effluent and river water samples, indicating potential concern for human exposure. In summary, our findings show the continued role of wastewater as a significant AR reservoir and underscores the considerable impact of wastewater discharge on aquatic wildlife, which highlights the One Health nature of this issue.

Performance of zero-valent iron immobilized on activated carbon cloth for the removal of phenol from wastewater

BackgroundDischarge of large amounts of untreated industrial effluent into water bodies pose significant environmental challenges worldwide. This is due to the limitations of traditional wastewater treatment methods in the treatment of recalcitrant organic pollutants. Fenton processes involves the generation of hydroxyl radicals that are well suited to degrade organics in effluent water. This study focuses on reducing slag generation during Fenton processes and enhancing the reuse of nano-zero-valent iron (NZVI) through the immobilization of NZVI on activated carbon cloth (ACC) through a chitosan (CH) linker with phenol as a model pollutant.ResultsMicrostructural and spectroscopic techniques were employed to study the materials prepared and 37.5 wt% iron loading was achieved. Phenol degradation of 96.3% at 40 °C at pH of 3.0 with 50 mM H2O2 was achieved using ACC-CH-NZVI. Adsorption and degradation studies carried out using ACC-CH-NZVI catalyst revealed that phenol adsorption onto ACC-CH-NZVI fits the Langmuir isotherm model, following the pseudo-second-order kinetic model and first-order reaction kinetics. Thermodynamic studies indicate the non-spontaneous, endothermic and irreversible nature of the removal process. Comparing ACC-CH-NZVI with ACC and ACC-CH, phenol removal using ACC drops from 87.8 to 39%, while using ACC-CH, the removal efficiency drops from 73 to 20.9% and using ACC-CH-NZVI, phenol removal drops from 96.3 to about 70% and total organic carbon removal drops from 79 to about 60% with minimal iron leaching, highlighting the superior performance of ACC-CH-ZVI and the role of NZVI in enhancing phenol removal.ConclusionsThe catalyst demonstrated good stability for phenol degradation to about 70% phenol removal from simulated wastewater and 60% TOC removal from industrial wastewater after five treatment cycles with minimal Fe leaching.Graphical abstract

The Veterinarian’s Role in Biocontainment Research Animal Facilities and Prevention of Spread of Pathogens: A Case of Nigeria and South Africa

Infections acquired in research laboratories and unintentional pathogen escapes from breaches in biocontainment pose risks to humans and the environment, necessitating the need for effective biosafety and biosecurity management frameworks in biocontainment research animal facilities (BRAFs). We examine key biosafety issues associated with BRAFs, including inadequate decontamination procedures for wastewater and experimental samples, handling high biosafety level pathogens in lower-level laboratories, risks of animal bites and sharps injuries, contamination of bedding and enrichment materials, and improper management and transportation of biohazard samples. Additionally, we discuss the role of veterinarians in research animal facilities and the challenges they encounter in maintaining biocontainment standards. We emphasise the importance of routine monitoring of effluent water to detect possible disease outbreaks. We recommend a thorough investigation of disease outbreaks to identify potential sources of pathogen release from BRAFs, which could serve as hotspots for future disease outbreaks. Findings from such investigations will inform the development of policies aimed at safeguarding human populations from future pandemics and preventing BRAFs from becoming sources of infectious disease outbreaks.

Evaluation of emergency skin decontamination protocols in response to an acid attack (vitreolage)

The incidence of “acid attacks” (vitreolage) is a global concern, with those affected often receiving lifelong medical care due to physical and psychological damage. The purpose of this study was to evaluate the effectiveness of several emergency skin decontamination approaches against concentrated (>99 %) sulphuric acid and to identify the effective window of opportunity for decontamination. The effects of four decontamination methods (dry, wet, combined dry & wet and cotton cloth) were assessed using an in vitro diffusion cell system containing dermatomed porcine skin. Sulphuric acid (H2SO4) was applied to the skin with decontamination protocols performed at 10 s, 30 s, 8 min, and 30 min post exposure. Skin damage was quantified by tritiated water (3H2O) penetration, receptor fluid pH and photometric stereo imaging (PSI), with quantification of residual sulphur (by SEM-EDS) to determine overall decontamination efficiency. Skin translucency (quantified by PSI) demonstrated a time-dependent loss of dermal tissue integrity from 10 s. Quantification of dermal sulphur content confirmed the rapid (exponential) decrease in decontamination efficiency with time. The pH of the water effluent indicated complete neutralisation of acid from the skin surface after 90 s of irrigation. Wet decontamination (either alone or immediately following dry decontamination) was the most effective intervention evaluated, although no decontamination technique was statistically effective after 30 s exposure to the acid. These data demonstrate the time-critical consequences of dermal exposure to concentrated sulphuric acid: we find no practical window of opportunity for acid decontamination, as physical damage is virtually instantaneous.

Ecotoxicological risk assessment of triclosan, an emerging pollutant in a riverine and estuarine ecosystems: A comparative study

Triclosan (TCS), an antibacterial biocide, pervades water and sediment matrices globally, posing a threat to aquatic life. In densely populated cities like Mumbai, rivers and coastal bodies demand baseline TCS data for ecotoxicological assessment due to the excessive use of personal care products comprising TCS. This pioneering study compares spatiotemporal TCS variations and risks in freshwater and marine ecosystems employing multivariate analysis of physicochemical parameters. Over five months (January to May 2022), Mithi River exhibited higher TCS concentrations (water: 1.68 μg/L, sediment: 3.19 μg/kg) than Versova Creek (water: 0.49 μg/L, sediment: 0.69 μg/kg). Principal component analysis revealed positive correlations between TCS and physicochemical parameters. High-risk quotients (>1) underscore TCS threats in both water bodies. This study furnishes crucial baseline data, emphasizing the need for effective treatment plans for TCS in effluent waters released into the adjacent aquatic systems.

The Integrating Impacts of Extreme Weather Events and Shrimp Farming Practices on Coastal Water Resource Quality in Ninh Thuan Province, Vietnam

Ninh Thuan is a coastal province in the central region of Vietnam and is characterized by a climate that is the hottest and driest in the country. Vietnam is also one of the top five countries most vulnerable to the effects of climate change worldwide. The objective of this study was a thorough evaluation of the quality of water supply sources and the impacts of water effluents from shrimp farms in Ninh Thuan province. The comprehensive evaluation was based on an understanding of the water–wastewater cycle employed in coastal shrimp cultivation. We combined qualitative and quantitative analyses in undertaking this study. Secondary data of groundwater and coastal water from the local periodic water quality monitoring program and national technical regulations were collected in the qualitative approach. We also integrated participatory rural appraisal techniques and field observations to understanding shrimp cultivation and the environmental and social impacts of shrimp farm effluents. The quantitative assessment consisted of measuring groundwater and wastewater contamination from shrimp ponds. As a result, four main reasons for water pollution issues were determined including extreme weather events, shrimp cultivation practices, degraded infrastructure, and mismanagement by local governance. Shrimp cultivation practices (feeding, using chemicals) have resulted in elevated levels of suspended solid (TSS, total Coliform), organic and carbon matter (BOD5, COD), and excessive nutrients (total Nitrogen, NO2-N, NO3-N, PO4-P). According to a local monitoring program, the coastal water and groundwater have experienced nutrient pollution. Groundwater sampling near the shrimp farms identified salinization elevated levels of Coliform from local domestic sewage sources. This study resulted in an integrated approach that evaluated the combined effects of extreme weather events and shrimp farming practices on the quality of coastal water. Also, the finding can be useful in recommending remedial water treatment technologies as a follow-on phase.

Prediction of residual aluminum concentration and size in water plants of South-to-North Water Transfer Project through machine learning

Effluent water in South-to-North Water Transfer Project is complicated, leading to possibility of excessive residual aluminum if the coagulant dosage is improper. There exists certain risk for controlling residual aluminum based on experiences, while using machine learning can offer appropriate dosage based on the effluent water parameters. Much attention has been paid to the aluminum below 0.45 μm while for water plant with sand filter only, aluminum over 0.45 μm can still be remnant in the effluent water. In this study, machine learning algorithms were applied for the prediction of pH, aluminum concentration and size after coagulation based on the water parameters and ESI-TOF-MS results of the coagulant. The results showed that conventional neural network (CNN) showed best prediction ability compared with BP network, random tree and support vector machine, whose R2 was 0.936. The predicted results showed that the aluminum size decreased as the basicity increased at the same dosage, the concentration of aluminum between 20 and 30 μm dropped from 65 % to 24 %.

Stormwater quality and microbial ecology in an urban rain garden system

Rain gardens are an alternative to traditional drainage, able to lower flood risk and reduce environmental contamination from stormwater. Removal of contaminants by rain gardens is driven by both physical processes (such as filtration and sedimentation) and biological metabolic processes by soil microorganisms. To better understand rain garden performance, this study explored the impact of rain gardens on pollution removal and microbial composition and function using rain gardens fed real stormwater from a busy road. Each rain garden had different grain size and hydraulic conductivities as these parameters have been argued to impact pollution removal. All four rain gardens were able to reduce the contaminant load in the stormwaters, reducing the concentration of dissolved metals, suspended solids and chemical oxygen demand. Significantly, road salting in the winter did not cause dissolved metals to be released from the rain gardens, suggesting that rain gardens can continue to reduce contaminant loads during winter salting regimes. Some variation in pollutant removal was seen between the soils tested, but overall no clear trend could be identified based on grain size and hydraulic conductivity with all rain gardens performing broadly similarly. The rain garden soil altered the microbial community in the stormwater, resulting in greater taxonomic evenness and functional richness in the effluent water compared to the influent. Functional richness of the soils was also higher than that of the input waters, indicating that the microbes in the rain gardens were able to perform a wider range of functions than those of the influent. Effluent and soil microbiology was more impacted by sampling date than soil grain size, which may be a result of the soil communities maturing and changing over time. As greater numbers of rain gardens are installed to tackle flooding from climate change, it is important to ensure the environment is protected from urban contaminants in the stormwater. The results in this study further highlight the ability of rain gardens to undertake this important task.

Removal of Micropollutants in Water Reclamation by Membrane Filtration: Impact of Pretreatments and Adsorption.

Organic micropollutants (OMPs) present in water and wastewater are in the spotlight because of their potentially harmful effects even at low concentrations and the difficulties of their elimination in urban wastewater treatment plants (UWWTPs). This study explores the impact of some membrane filtration processes on the removal of a group of 11 OMPs with an eye on the effects of two pretreatments (i.e., coagulation and adsorption onto powdered activated carbon (PAC)) and the adsorption of OMPs onto the membranes on the overall removal. For this purpose, ultrafiltration (UF) and nanofiltration (NF) experiments were conducted with selected OMPs spiked in ultrapure water and secondary effluents from UWWTPs. It was observed that the adsorption of OMPs onto the membranes was influenced by the characteristics of the membranes, as well as the presence of effluent organic matter (EfOM). Since adsorption was the dominant mechanism for the rejection of OMPs by UF membranes, a study of the adsorption equilibrium of the micropollutants using UF membrane pieces as the adsorbent was conducted. The adsorption isotherms for the most hydrophobic OMPs fitted the Langmuir model. The efficiency of coagulation and powdered activated carbon (PAC) adsorption coupled with UF were also investigated. Both pretreatments alleviated membrane fouling and improved the rejection of organic and inorganic matter. The PAC pretreatment significantly improved the removal of OMPs in the combined PAC/UF process. The best options for achieving reclaimed water with satisfactory physicochemical quality, nearly devoid of OMPs and microorganisms, and suitable for diverse reuse purposes are either the NF treatment or the combination of PAC/UF.

Physiological effects of feeding whiteleg shrimp (Penaeus vannamei) with the fresh macroalgae Chaetomorpha clavata

In shrimp farming, the use of commercial feed can generate high nutrient loads in water bodies, and often constitute the most substantial component of production costs. Alternatives that seek to reduce the use of commercial feed can therefore both mitigate environmental impacts and reduce operational expenses. One possible strategy is incorporation of algae that crustaceans can consume with minimal biological effect into integrated multi-trophic aquaculture (IMTA) systems. Our objective was to determine whether the marine shrimp Penaeus vannamei feeds on the fresh macroalga Chaetomorpha clavata and whether the partial substitution (50 %) of this alga in its diet influences its physiology. Survival, growth, and a range of physiological processes including ingestion, defecation, metabolism, nitrogen excretion, oxidized energy substrate, hepatosomatic index, and energy budget were assessed in P. vannamei shrimp fed commercial feed (100 %, control) versus shrimp fed a combination of commercial feed and algae (50 % each). Our results showed that P. vannamei fed on C. clavata, and that there were no significant differences in mortality and growth rates (∼11 %) between shrimp fed with the two diets. The ingestion rate was higher in the group fed with macroalgae, however the defecation rate and digestibility were not affected. In both groups, no differences were detected in metabolic rates, growth, nitrogenous excretion, and egestion between shrimp fed the different diets, nor in oxidized energy substrates and the hepatosomatic index. Our results show that substituting 50 % of the feed with C. clavata represents a viable alternative to full commercial feed since it had minimal impact on the physiological functions of P. vannamei. In addition to the economic benefit of reducing the amount of feed used during culture, the use of algae also reduces contamination of effluent water, thereby improving environmental sustainability and water quality.

Does stricter sewage treatment targets policy exacerbate the contradiction between effluent water quality improvement and carbon emissions mitigation? An evidence from China

Rapid expansion and upgrading of wastewater treatment facilities globally, driven by stricter wastewater policies, significantly contribute to carbon emissions. China has contributed 30 % of carbon emissions in the world, 1 % of which comes from wastewater treatment, necessitating more understanding of the impact of policies, especially the stringent “10-Point Water Plan” policy. From a micro perspective, this study uses the difference-in-differences method to analyze the impact of wastewater treatment policies on water and carbon issues in China’s 2894 wastewater treatment plants (WWTPs), and delves into the heterogeneity, and mechanisms across various dimensions. The results show that stricter sewage treatment policy decrease effluent concentration of the chemical oxygen demand (COD) by 2.35 %, and also cause a 1.74 % rise in carbon emissions per 10,000 m3 of wastewater treated, intensifying the short-term contradiction, while the contradictions may fall in the long term. It is more significant in southern regions and the cities with lower environmental regulation intensity. Also, there are significant differences in different wastewater treatment technology and scale. Significant improvements in effluent water quality are observed in WWTPs with 100,000 to 200,000 m3/day capacity and those using biofilm treatment technology. Through mechanism analysis, reasonable expansion of urban pipelines and WWTPs, promotion of biofilm treatment technology, reduction of energy consumption, and improvement of pollutant reduction efficiency are feasible paths to improve water quality and reduce carbon emissions. This research provides a perspective on solving water-carbon contradictions in WWTPs, holding critical significance for urban wastewater treatment and carbon emission management.

Pre-coating of stainless-steel mesh support material with wastewater treatment plant sludges in a dynamic membrane filtration process

This study focuses on wastewater treatment plant sludges to be deposited on large aperture meshes. In a column reactor that is filled with treatment plant sludges, a series of batch experiments were performed with varying sizes of stainless-steel mesh modules (75 to 300 μm) as a support media to form a dynamic membrane. Primary, secondary, and polyelectrolyte-added sludges were used both individually and in combination to investigate the performance (filterability, permeate quality, and dynamic layer formation ability) of the varying pore-size meshes at high fluxes. The results were superior when primary and secondary sludges were combined in the creation of a dynamic cake layer, as opposed to individual sludge usage. Mesh sizes were shown to have no effect on performance, providing turbidity of <10 NTU for a short duration (10 min) of filtration. Cake formation rates were calculated as 23.0 NTU/min, 19.48 NTU/min, 7.62 NTU/min, and 6.94 NTU /min for 100, 150, 200, and 300 μm support meshes, respectively. For the first time in literature, effluent water turbidity decreases to <5 NTU for 300 μm support mesh at high fluxes. Scanning electron microscope images showed that fibers that may originate from the primary sludge could enhance the formation of stable cake layer. This study is important for creating high-performing dynamic membrane filtration on large aperture meshes, which can be used as a cost-effective and reliable filter for wastewater treatment.