Pathogens Removal in a Sustainable and Economic High-Rate Algal Pond Wastewater Treatment System

This study evaluates the efficiency of a sustainable technology represented in an integrated pilot-scale system, which includes a facultative pond (FP), a high-rate algal pond (HRAP), and a rock filter (RF) for wastewater treatment to produce water that complies with the Egyptian standards for treated wastewater reuse. Still, limited data are available on pathogen removal through HRAP systems. Thus, in this study, the performance of the integrated system was investigated for the removal of Escherichia coli (E. coli), coliform bacteria, eukaryotic pathogens (Cryptosporidium spp., Giardia intestinalis, and helminth ova), somatic coliphages (SOMCPH), and human adenovirus (HAdV). Furthermore, physicochemical parameters were determined in order to evaluate the performance of the integrated system. The principal component analysis and non-metric multidimensional scaling analysis showed a strong significant effect of the integrated system on changing the physicochemical and microbial parameters from inlet to outlet. The mean log10 removal values for total coliform, fecal coliform, and E. coli were 5.67, 5.62, and 5.69, respectively, while 0.88 log10 and 1.65 log10 reductions were observed for HAdV and SOMCPH, respectively. The mean removal of Cryptosporidium spp. and Giardia intestinalis was 0.52 and 2.42 log10, respectively. The integrated system achieved 100% removal of helminth ova. The results demonstrated that the system was able to improve the chemical and microbial characteristics of the outlet to acceptable levels for non-food crops irrigation. Such findings together with low operation and construction costs of HRAPs should facilitate wider implementation of these nature-based systems in remote and rural communities. Overall, this study provides a novel insight into the performance of such systems to eliminate multiple microbial pathogens from wastewater.

MULTI-CRITERIA ASSESSMENT MODEL TO IDENTIFY SUITABLE AREAS FOR TREATED WASTEWATER REUSE IN AGRICULTURE

A model of land suitability analysis for irrigation with treated domestic wastewater is presented. The model integrates tools of Multi-Criteria Evaluation with Geographical Information Systems. Several criteria were selected to adapt the model to the conditions and characteristics of the case study. The adaptation process included field visits, a bibliographical review, and personal interviews with local actors and experts. Six constraints and 10 factors were selected and 3158 hectares suitable for the activity were identified. The areas were classified into three categories of aptitude, representing high fitness sites close to the current wastewater treatment plant. The developed tool allowed us to integrate different criteria to assess site suitability for wastewater reuse, with the advantage that the tool can be adapted to other regions and/or objectives.

Insights into Gastrointestinal Virome: Etiology and Public Exposure

Recycled wastewater is widely used owing to the potential shortage of water resources for drinking purposes, recreational activities, and irrigation. However, gut microbiomes of both human beings and animals negatively affect this water quality. Wastewater contamination is continuously monitored, using fecal contamination indicators or microbial source tracking approaches, to oppose arising enteric infections. Viral gastroenteritis is considered a principal manifestation of waterborne pathogenic virome-mediated infections, which are mainly transmitted via the fecal-oral route. Furthermore, acquired enteric viromes are the common cause of infantile acute diarrhea. Moreover, public exposure to wastewater via wastewater discharge or treated wastewater reuse has led to a significant surge of public health concerns. In this review, we discussed the etiology of waterborne enteric viromes, notably gastrointestinal virus infections, and public exposure to municipal wastewater. Conclusively, the early human virome is affected mainly by birth mode, dietary behavior, and maternal health, and could provide a signature of disease incidence, however, more virome diversification is acquired in adulthood. A multi-phase treatment approach offered an effective means for the elimination of wastewater reuse mediated public risks. The insights highlighted in this paper offer essential information for defining probable etiologies and assessing risks related to exposure to discharged or reused wastewater.

The Economics of Fruit and Vegetable Production Irrigated with Reclaimed Water Incorporating the Hidden Costs of Life Cycle Environmental Impacts

The estimation and quantification of external environmental costs (hidden costs) are crucial to sustainability assessments of treated wastewater reuse projects. These costs, however, are rarely considered in economic analysis studies. In this work, monetized life cycle assessment (LCA) and life cycle costing (LCC) were combined into a hybrid model to calculate cradle-to-farm gate external environmental costs (EEC) and internal costs (IC) of producing 1 t of plant-based product irrigated with reclaimed water in a Mediterranean context. The total cost was calculated by combining monetized LCA and LCC results. The results for the crops under consideration were 119.4 €/t for tomatoes, 344.4 €/t for table grapes, and 557 €/t for artichokes. Our findings show that there are significant hidden costs at the farm level, with EEC accounting for 57%, 23%, and 38% of the total cost of tomatoes, table grapes, and artichokes, respectively. Electricity use for water treatment and fertilization generated most of the EEC driven by the global warming, particulate matter, acidification, and fossil resource scarcity impact categories. When compared to groundwater, the higher internal costs of reclaimed water were offset by lower external costs, particularly when supported by low-energy wastewater treatment. This demonstrates that incorporating EEC into economic analyses might generate a better understanding of the profitability of treated wastewater reuse in crop production. In Italy and the Mediterranean region, research on the sustainability of water reuse in irrigation through life cycle thinking is still limited. Using a multi-metric approach, our analysis brought new insights into both economic and environmental performance – and their tradeoff relationships in wastewater reuse for irrigation of agricultural crops. In future research, it would be of interest to use different monetization methods as well as to investigate social externalities to explore their size and role in the total external costs.

Analysis of the Water–Energy Nexus of Treated Wastewater Reuse at a Municipal Scale

Treated wastewater has the potential to be a feasible alternative to supply non-potable uses and avoid water scarcity in urban areas, but it is important to understand and compare the associated energy consumption and CO2 emissions. This study presents a comparative analysis of the water–energy nexus associated with the traditional water supply and to the alternative reuse of treated wastewater, both for non-potable purposes. A case study of a Portuguese municipality was considered, regarding golf course irrigation and municipal gardens irrigation. A balance between production and demand was established, and the energy consumption and CO2 emissions were calculated considering the supply with drinking water and with treated wastewater. Three scenarios were defined to analyze the water–energy nexus for different configurations of the potential end-uses: (1) golf course supply, (2) municipal irrigation supply and (3) simultaneous supply to the golf course and to municipal irrigation. A quality analysis was also carried out by comparing the records from discharged wastewater quality parameters with the limits presented in the legislation for each proposed non-potable use. The results show that all scenarios present significant annual savings from using treated wastewater instead of drinking water from the public network, especially scenarios 1 and 3, that consider the golf course irrigation (water costs decrease by about 60,000.00 EUR/year). Regarding the water–energy nexus, this study reveals that treated wastewater spends less energy on its production and supply and produces fewer CO2 emissions. The energy savings can reach an average value of about kWh/year, with 5300 fewer kg of CO2 emitted in the best scenario.

Assessment of Treated Wastewater Reuse in Drip Irrigation under Different Pressure Conditions

This study aims to investigate the influence of treated wastewater (TWW) on the hydraulic performance of drip irrigation emitters. A field experiment was conducted in order to test two types of online emitters, a low pressure (LP) and a standard pressure (SP), at different working pressures (0.25 bar, 0.50 bar, and 1.00 bar) using TWW. The emitters were initially evaluated in the laboratory and the field for the discharge exponent (X), discharge coefficient (Kd), average emitter discharge (Qavg), coefficient of variation (CV), distribution uniformity (DU), the mean discharge ratio (Dra), and the main degree of clogging (DC). The main effect of the emitters on the hydraulic parameters of irrigation performance was not significant, while the operational pressure and operational time of irrigation had a significant effect. For the LP emitter, the average emitter discharge was 7.6, 7.7, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. For the SP emitter, the average emitter discharge was 7.6, 7.8, and 7.8 Lh−1 at 0.25, 0.50, and 1.00 bar, respectively. The EU values for the LP and SP emitters varied from low to moderate at 0.25 bar, as the EU values at 0.50 and 1.00 bar were considered high for both emitter types.

Evaluation of the Performance and Quality of Wastewater Treated by M’zar Plant in Agadir, Morocco

The aim of our study is based on the characterization of the effluents treated by the M’zar plant, the monitoring of its purification performance after each treatment stage and the benefits of treated wastewater reuse in Souss-Massa region. Physico-chemical and bacteriological analyses were performed monthly from May 2019 to September 2020 on four types of water: Raw Water (RW), Settled Water (SW), Filtered Water (FW) and Purified Water treated by ultraviolet radiation (PWUV). After treatment, the pH values were close to neutrality and the concentrations of COD, BOD5, SM and bacteriological parameters were below the limits recommended by Moroccan standards, with a satisfactory abatement rate (between 97.5% and 100%), with the exception of electrical conductivity, which recorded very high values (3.7 dS/cm in PWUV) due to the salt discharged by the fish industries. In fact, the treated wastewater is rich in nitrates (289.24 mg/L in PWUV) and their reuse in agriculture can therefore contribute to making significant savings in terms of fertilization (2.08 t/day of nitrogen with a daily flow of 30,000 m3/day). Furthermore, a daily quantity of 2 to 5 tons of sludge is discharged, containing 40% to 60% of dry volatile matter, which results in the biogas production of 1275 m3/day/decanter.