Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries - case studies from Cochabamba, Bolivia.

Wastewater irrigation is a common practice in developing countries due to water scarcity and increasing demand for food production. However, there are health risks and ecological risks associated with this practice. Small-scale wastewater treatment plants (WWTPs) intend to decrease these risks but still face management challenges. This study assessed how the management status of five small-scale WWTPs in Cochabamba, Bolivia affects health risks associated with consumption of lettuce and ecological risks due to the accumulation of nutrients in the soil for lettuce and maize crops. Risk simulations for three wastewater irrigation scenarios were: raw wastewater, actual effluent and expected effluent. Results showed that weak O&M practices can increase risk outcomes to higher levels than irrigating with raw wastewater. Improving O&M to achieve optimal functioning of small-scale WWTPs can reduce human health risks and ecological risks up to 2 log10 DALY person-1 year-1 and to 2 log10 kg nitrogen ha-1 accumulated in soil, respectively.

Sanitary quality improvement of fish produced in the northern Benin cotton basin water reservoirs by cage culture and fish transfer in agricultural contaminant-free water: human health implications.

Northern Benin water reservoirs may remain valuable resources for fish production if the ecotoxicological risks related to agricultural pesticides are eradicated. The present work was undertaken (i) to evaluate sanitary quality and human health implications of fish (Clarias gariepinus and Oreochromis niloticus) reared in cages compared with those produced in pens installed in a contaminated water reservoir (Batran) and a reference water reservoir (Songhaï) and (ii) to test the efficacy of fish transferring to water without agricultural contaminants on fish health status. Pathogenic bacteria and pesticide residues were analyzed by phenotypic and biochemical identification and gas chromatography coupled with mass spectrometry, respectively. For both species, Aeromonas species occur in fish reared in pens at Batran. In Batran, regardless of infrastructure and species, residues of 4,4'-DDE (Dichlorodiphenyldichloroethylene) (1.4-4.9 µg/kg) and Chlorpyriphos (ethyl) (2.8-12.1 µg/kg) were measured, while only the last molecule was found in C. gariepinus from Songhaï (8.9-8.10 µg/kg). Irrespective of the species in the Batran water reservoir, Chlorpyriphos (ethyl) concentration was higher in cages and lower in pens, while 4, 4'-DDE was more concentrated in fish farmed in pens. Levels of these pesticide residues were well below World Health Organization/Food and Agriculture Organization permissible limits and the risk analyzed indicates no potential adverse health implications in consumption of these fish. Also, fish bacteriological quality was in compliance with the international standards. The fish decontamination approach used herein results in a reduction of the splenic macrophage phagocytic activity in both studied fish species.

Computational and statistical modeling for parameters optimization of electrochemical decontamination of synozol red dye wastewater.

In this study, computational and statistical models were applied to optimize the inherent parameters of an electrochemical decontamination of synozol red. The effect of various experimental variables such as current density, initial pH and concentration of electrolyte on degradation were assessed at Ti/RuO0·3TiO0·7O2 anode. Response surface methodology (RSM) based central composite design was applied to investigate interdependency of studied variables and train an artificial neural network (ANN) to envisage the experimental training data. The presence of fifteen neurons proved to have optimum performance based on maximum R2, mean absolute error, absolute average deviation and minimum mean square error. In comparison to RSM and empirical kinetics models, better prediction and interpretation of the experimental results were observed by ANN model. The sensitive analysis revealed the comparative significance of experimental variables are pH = 61.03%>current density = 17.29%>molar concentration of NaCl = 12.7%>time = 8.98%. The optimized process parameters obtained from genetic algorithm showed 98.6% discolorization of dye at pH 2.95, current density = 5.95 mA cm-2, NaCl of 0.075 M in 29.83 min of electrolysis. The obtained results revealed that the use of statistical and computational modeling is an adequate approach to optimize the process variables of electrochemical treatment.

Comparative assessment of sewage sludge disposal alternatives in Mashhad: a life cycle perspective.

Municipal wastewater treatment facilities produce a lot of sludge which is concentrated with different pollutants. The sustainable design of the sludge disposal alternatives is of crucial importance for touristic cities like Mashhad in Iran. Increasing sludge generation and its accumulation in the city and more stringent legislations highlight the challenge of sludge disposal, recently. This study compares different alternatives to reach maximum possible environmental benefits as well as the most cost-effective technologies. In this study, life cycle analysis (LCA) assesses different scenarios for disposal of sewage sludge which is aerobically treated and dewatered for two real case studies. Alteymore and KhinArab are wastewater treatment units in the city. The scenarios include incineration, composting, and landfilling alternatives. The incineration and landfill scenarios are the least interesting solutions according to different life cycle impact categories. The heavy metals' emission to the soil worsens their impacts. Also, lifecycle cost analysis reveals that composting scenario is more cost-saving than others. However, main disadvantage of the composting scenario is its contribution in freshwater eutrophication. To move towards sustainability, the composting scenario is here determined as the best scenario for sludge disposal in Mashhad.

A call-to-action for sustainability in dialysis in Brazil / Um apelo pela sustentabilidade na diálise no Brasil

ABSTRACT Human-induced climate change has been an increasing concern in recent years. Nephrology, especially in the dialysis setting, has significant negative environmental impact worldwide, as it uses large amounts of water and energy and generates thousands of tons of waste. While our activities make us responsible agents, there are also several opportunities to change the game, both individually and as a society. This call-to-action intends to raise awareness about environmentally sustainable practices in dialysis and encourages this important discussion in Brazil.

RESUMO A mudança climática induzida pela atividade humana tem sido foco de preocupações crescentes nos últimos anos. A nefrologia, particularmente a diálise, produz significativos impactos ambientais em todo o mundo em virtude da grande utilização de água e energia e da geração de milhares de toneladas de resíduos. Embora nossas atividades nos tornem agentes responsáveis, há várias oportunidades para mudar esse cenário, tanto individualmente como em sociedade. O presente artigo pretende ampliar a conscientização sobre práticas ambientalmente sustentáveis em diálise e estimular essa importante discussão no Brasil.

Statistical analysis of the effluent quality of 231 on-site sanitation facilities in France monitored during a 6-year period.

On-site wastewater treatment systems are approved by the French regulation based on the results of platform tests following the European standard NF EN 12566-3. In addition to this approval for the treatment system, at least 90% of outlet concentrations have to be below 30 mg L-1 for total suspended solids (TSS) and 35 mg L-1 for biochemical oxygen demand. The aim of this study is to evaluate the effluent quality of these treatment systems on site, i.e. under real operating conditions, and to assess their performances. Between 2011 and 2016, 1,286 treated wastewater samples were taken from 231 on-site sanitation facilities in France. Data collected are heterogeneous and a robust statistical methodology (using a generalized log-linear model) was used to study the effects of four explanatory variables (treatment systems, loading rate, aging and sampling methods) on the distribution of treated wastewater concentrations. The model calculates median outlet concentrations depending on the effects identified. Its application allowed studying and comparing the outlet median concentrations of 21 on-site sanitation systems classified into nine categories and three groups. Four treatment systems out of the 21 monitored showed TSS median outlet concentrations below 10 mg L-1 and four treatment systems have TSS medians higher than the regulatory threshold of 30 mg L-1.

Optimization of operating conditions for the acidification metabolites production with waste sludge using response surface methodology (RSM).

The acidification liquid of waste activated sludge (WAS) could be used as the additional carbon source of biological nutrient removal. Recently, the optimization of operating conditions for the acidification metabolites has attracted much attention. In this study, a three-factor Box-Behnken design (BBD) was applied to determine the relative importance of the various factors and the optimum operating during acidification using response surface method (RSM). The importance of the individual variables on the production of soluble chemical oxygen demand (SCOD) was suspended solids (SS) > shaking rate > initial oxidation-reduction potential (ORP). The increase on SS content led to a decrease on the acidification degree. Low SS could promote mass exchange and microbial activity. The maximum SCOD yield (9288.5 mg/L) was predicted under the optimum condition at 8.0 g/L SS, 144.0 mV initial ORP, and 60.0 r/min shaking rate. Also, the releasing of soluble protein and carbohydrate was calculated as responses. The individual effect of shaking rate and initial ORP had significant effect on soluble protein and carbohydrate releasing, respectively. This study would provide valuable information for increasing the efficiency of acidification.

A call-to-action for sustainability in dialysis in Brazil.

Human-induced climate change has been an increasing concern in recent years. Nephrology, especially in the dialysis setting, has significant negative environmental impact worldwide, as it uses large amounts of water and energy and generates thousands of tons of waste. While our activities make us responsible agents, there are also several opportunities to change the game, both individually and as a society. This call-to-action intends to raise awareness about environmentally sustainable practices in dialysis and encourages this important discussion in Brazil.

Development of generalized empirical models for comparing effectiveness of wastewater nutrient removal technologies.

The effectiveness of nutrient removal approaches was quantified at four wastewater treatment facilities (WWTFs) using mechanistic models. Generalized empirical models were developed applying statistical methods on the predicted values characterizing nutrient removal as a function of influent wastewater quality. The empirical models provide a framework to estimate nutrient removal effectiveness and inform system-level decisions on technology adoption. When carbon limited, more sophisticated approaches like five-stage Bardenpho and nitrite shunt provide the most notable benefit in removal efficiency (67% ± 3.3% and 89% ± 2.8%, respectively for total nitrogen (TN)), but little benefit is estimated under non-carbon-limited conditions between traditional solutions like anaerobic, anoxic, oxic (A2O), and advanced process configurations like five-stage Bardenpho (82% ± 2.8% and 85% ± 3.3%, respectively for TN). Sidestream physical/chemical processes can provide improvement in removal efficiency particularly at carbon-limited WWTFs, but negligible benefit is estimated with adoption of sidestream biological processes.

Robust model for estimating pumping station characteristics and sewer flows from standard pumping station data.

Flow data represent crucial input for reliable diagnostics of sewer functions and identification of potential problems such as unwanted inflow and infiltration. Flow estimates from pumping stations, which are an integral part of most separate sewer systems, might help in this regard. A robust model and an associated optimization procedure is proposed for estimating inflow to a pumping station using only registered water levels in the pump sump and power consumption. The model was successfully tested on one month of data from a single upstream station. The model is suitable for identification of pump capacity and volume thresholds for switching the pump on and off. These are parameters which are required for flow estimation during periods with high inflows or during periods with flow conditions triggering pump switching on and off at frequencies close to the temporal resolution of monitored data. The model is, however, sensitive within the transition states between emptying and filling to observation errors in volume and on inflow/outflow variability.

Modelling biofilm anaerobic reactor with effluent from hydrolytic/acidogenic reactor as substrate.

This work presents modelling of an anaerobic biofilm reactor using ceramic bricks as support. The results were compared with the experimental data. It was observed that the substrate concentration curves showed the same tendency. The methane formation curves showed significant differences. The substrate removal efficiency was 83%. In the steady state, the experimental data were higher than the model, from the result the substrate degrading bacteria grew enough to reach biofilm and that the effect of the shear stress was more significant as the biofilm increased in thickness. To the methane production, the model in steady state reached a maximum value of 0.56 m3 CH4/m3 *d and the experimental data reached 0.42 (m3 CH4/m3 * d). The biofilm thickness calculated by the model was 14 µm.

Performance evaluation of ETP from pesticide manufacturing industry by using WWQI and multivariate statistical analysis.

The appropriate operation of wastewater treatment plants is essential to maintain the quality of treated water. The aim of the present study is to monitor the effluent quality by applying the Wastewater Quality Index (WWQI) and statistical method. The influent and effluent wastewater samples were collected from an Effluent Treatment Plant (ETP) of pesticide manufacturing industry in Tamil Nadu, India. The study was carried out during the period 2014-2018. The physicochemical parameters were analyzed to determine the biodegradable and non-biodegradable contaminants in the wastewater. The organic removal in ETP for high Total Dissolved Solids (TDS) wastewater treatment was 97-100% and low TDS wastewater treatment was 96-99%. The overall quality of the wastewater was determined by WWQI using irrigation standards. The quality of all the influent samples was poor. The WWQI of high TDS effluent samples varied from marginal to good. The low TDS effluent quality varied from fair to excellent. The interdependencies between the variables were observed using Principal Component Analysis (PCA). From the influent and effluent variables, five and two PCA components were extracted with 92 and 85% of the total dataset information, respectively. The correlation analysis was carried out to observe the interrelationship between the wastewater quality parameters. The regression model achieved 99% of accuracy for fitting the model with the calculated WWQI. The final effluent showed a higher removal efficiency and better quality to reuse for irrigation. It was concluded that the ETP of the PMI is maintained properly and can be also applied to other industrial wastewater. Graphical abstract.

Stormwater inflow loading of polycyclic aromatic hydrocarbons into urban domestic wastewater treatment plant for separate sewer system.

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants present in wastewater, and determination of their sources is important for their management in the environment. In this study, stormwater loading of PAHs during rainfall periods was evaluated for sewage inflow into a wastewater treatment plant (WWTP) for a separate sewer system. To accomplish this, sewage inflow volumes, suspended solid concentrations, and PAH concentrations were measured during eight rainfall events and on two no-rainfall days at the inlet of the plant. Based on a comparison between the rainfall and no-rainfall loading quantified by the measurements, excess PAH loadings with stormwater were evaluated for the rainfall events. The relationship between rainfall intensity and stormwater loading was then used to evaluate long-term stormwater loadings of water and PAHs. Their contributions to the sewage inflow were 0.7% and 1.0% for 1 year for water and the sum of 16 measured PAHs, respectively. Our measurements and estimates demonstrate that direct stormwater inflow is not a primary source of PAHs to the plant for this separate sewer system.

Constructed wetlands for winery wastewater treatment: A comparative Life Cycle Assessment.

A Life Cycle Assessment was carried out in order to assess the environmental performance of constructed wetland systems for winery wastewater treatment. In particular, six scenarios which included the most common winery wastewater treatment and management options in South-Western Europe, namely third-party management and activated sludge systems, were compared. Results showed that the constructed wetland scenarios were the most environmentally friendly alternatives, while the third-party management was the worst scenario followed by the activated sludge systems. Specifically, the potential environmental impacts of the constructed wetlands scenarios were 1.5-180 and 1-10 times lower compared to those generated by the third-party and activated sludge scenarios, respectively. Thus, under the considered circumstances, constructed wetlands showed to be an environmentally friendly technology which helps reducing environmental impacts associated with winery wastewater treatment by treating winery waste on-site with low energy and chemicals consumption.

Decision tree (DT), generalized regression neural network (GR) and multivariate adaptive regression splines (MARS) models for sediment transport in sewer pipes.

Sediment deposition in sewers and urban drainage systems has great effect on the hydraulic capacity of the channel. In this respect, the self-cleansing concept has been widely used for sewers and urban drainage systems design. This study investigates the bed load sediment transport in sewer pipes with particular reference to the non-deposition condition in clean bed channels. Four data sets available in the literature covering wide ranges of pipe size, sediment size and sediment volumetric concentration have been utilized through applying decision tree (DT), generalized regression neural network (GR) and multivariate adaptive regression splines (MARS) techniques for modeling. The developed models have been compared with conventional regression models available in the literature. The model performance indicators, showed that DT, GR and MARS models outperform conventional regression models. Result shows that GR and MARS models are comparable in terms of calculating particle Froude number and performing better than DT. It is concluded that conventional regression models generally overestimate particle Froude number for the non-deposition condition of sediment transport, while DT, GR and MARS outputs are close to their measured counterparts.

A simple sensitivity analysis of the turbulence-induced flocculation model of cohesive sediment.

In this study, the local and global sensitivity analyses of the Winterwerp model to the input parameters have been carried out using the Garson algorithm and the PaD2 method by virtue of an artificial neural network. The main results of the sensitivity analyses are that the model is most sensitive to the breakup parameter and that only two parameters (the floc aggregation and breakup parameters) are significant. The result that the model output is less sensitive to the choice of fractal dimension seems to imply that the modification work on the fractal dimension might be unnecessary.

Deciphering the Assembly Processes of the Key Ecological Assemblages of Microbial Communities in Thirteen Full-Scale Wastewater Treatment Plants.

Limited information is currently available on the assembly processes (deterministic vs. stochastic) shaping the compositions of key microbial communities in activated sludge (AS). The relative importance of deterministic and stochastic processes for key bacterial and archaeal assemblages (i.e., core-satellite and habitat generalist-specialist) in AS from 13 wastewater treatment plants in China was investigated using 16S rDNA amplicon sequencing. The results obtained indicated 1,388 and 369 core operational taxonomic units (OTUs), 1,038 and 1,683 satellite OTUs, 255 and 48 habitat generalist OTUs, and 192 and 111 habitat specialist OTUs for Bacteria and Archaea, respectively. The proportions of shared OTUs between core and habitat specialist communities were similar to or higher than those between core and habitat generalist communities, suggesting a stronger inter-linkage between the former two groups. Deterministic processes, indicated by abundance-based ß-null models, were responsible for shaping core communities, in which NH4-N, OrgC/OrgN, Cr, and Ni were the main controlling factors. In contrast, satellite communities were predominantly influenced by stochastic processes. Moreover, we found that deterministic and stochastic processes were mainly responsible for shaping the assembly of habitat specialists and generalists, respectively. However, the influence of deterministic factors on habitat specialists remains unclear. The present study provides novel insights into the assembly mechanisms of AS microbial communities.

Development of statistical predictive models for estimating the methane yield of Italian municipal sludges from chemical composition: a preliminary study.

The biochemical methane potential (BMP) of primary and biological sludge varies in a wide range, mostly depending on location, sewer characteristics, wastewater treatment plant design and operating conditions. BMP tests are useful to verify the performance of a full scale digester, but they are not yet a common procedure in the operation of most Italian facilities because of cost and test duration. Changes in the composition of sewage sludge can lead to a high variation of biogas production. Aimed at developing BMP predictive models based on low cost and fast analyses, this study investigated the chemical composition of 20 sludge samples by means of principal component and multiple linear regression analyses. Three preliminary predictive models were developed based on soluble organic nitrogen, volatile solids, carbohydrates, proteins, lipids and an operational parameter, the sludge retention time: the explained variance and the standard errors of prediction of BMP are in the range 77-81% and 21-34 NmLCH4·gVS -1, respectively. Models were evaluated on five additional samples: errors ranged 2-15% for four samples and about 54% for one sample, collected from a peculiar facility. Further data and variables describing the operation mode of the waterline would certainly improve the reliability and robustness of the models.

Large eddy simulation of turbulent flow structure in a rectangular embayment zone with different population densities of vegetation.

Dead-water zones (DWZs) in natural open channels, formed by embayment or consecutive groins, can provide favorable growth conditions for aquatic organisms. Although flow hydrodynamics in side-cavity zones have been well studied, the impact of vegetation on recirculating flow is rarely considered. This study adopts large eddy simulation (LES) to examine the flow field in a rectangular embayment zone with different population densities of vegetation. The numerical model is validated by mean streamwise velocity data collected near mid-depth in the physical experiment. Vegetation rearranges the circulation structure in the DWZ and weakens the velocity and turbulent kinetic energy. This negative effect increases with increasing population density. With the development of the shedding vortex induced in the front edge of the channel-embayment interface, the large-scale coherent structure forms in the mixing layer and is hardly affected by the variation of population density. As the population density increases, the mean retention time first decreases and then increases as a result of the combined action of three factors, namely, the large-scale coherent structure, the plant-induced Karman vortex street, and the blocking effect of dense vegetation.