Social life cycle assessment of microalgae-based systems for wastewater treatment and resource recovery

The aim of this study was to assess the social impacts of microalgae-based systems for wastewater treatment and bioproducts recovery by using the Social Life Cycle Assessment (S-LCA) tool. In particular, two systems were analysed: 1) a system treating urban wastewater, and 2) another system treating wastewater from the food industry. Moreover, these alternatives were compared to 3) a system for bioproducts production from microalgae grown in a standard growth medium. The recovered bioproducts in all the systems considered were: natural pigments, biogas and digestate, which can be reused as biofertilizer. Results showed that the scenario using standard growth medium was the one showing the best results in all impacts and stakeholder categories (up to 24-fold lower impacts depending on the impact category). This was mainly due to: i) the simplicity of the system, which consequently improves health and safety for workers; ii) the absence of contaminants which consequently improves health and safety, acceptability and olfactory impact for both consumers and the local community; iii) the presence of well-established legislation, regulatory frameworks, and full-scale deployment, which benefit value chain actors and society. Overall, this study also identified several social factors hindering a transition towards a circular bioeconomy in the microalgae-based systems for the wastewater treatment and resource recovery sector

Constructed wetlands for winery wastewater treatment: A review on the technical, environmental and socio-economic benefits

In wineries, wastewater production and solid waste generation can pose serious environmental threats. Winery wastewater production has a seasonal behavior and needs a treatment system that can adapt to these fluctuations while reducing costs, and environmental impacts and promoting other winery activities. The implementation of constructed wetlands (CWs) has been demonstrated to be a competitive solution for winery wastewater and sludge treatment. In this article, worldwide experiences over the last 25 years of CWs for winery wastewater treatment are reviewed. The review shows that the application of hybrid CWs coupled with anaerobic digestion can reduce >90 % of the organic pollutants and solids from winery wastewater while avoiding clogging. These efficiencies and advantages can be also attained with French vertical systems. Not only CWs have a good technical performance, but they also reduce up to >90 % the environmental impacts associated with winery wastewater treatment. It is due to low energy requirements, no chemicals consumption and avoidance of off-site management and transportation practices. In terms of costs, CWs can reduce up to 60 times the costs associated with winery wastewater treatment and management. More efforts should be made in order to define the social benefits of this technology and the quality of the recovered resources (e.g. treated water, fertilizer) in order to promote the circular economy without compromising human and ecosystem health

Post-treatment and agricultural reuse of digestate from low-tech digesters: A comparative life cycle assessment

The objective of this study was to analyse the environmental impacts of the post-treatment and agricultural reuse of digestate from a low-tech digester implemented in a small-scale farm in Colombia using the Life Cycle Assessment methodology. The scenarios considered were: 1) digestate post-treatment with a sand filter and its reuse in agriculture; 2) digestate post-treatment with a vermifilter and the production of compost, and 3) untreated digestate directly applied on the agricultural land (current scenario). Moreover, an economic analysis was also addressed. Results showed that the vermifilter was the most environmentally friendly scenario. It considerably reduced (by up to 9 times) the environmental impacts compared to the other scenarios. From an economic point of view, the implementation of the vermifilter generated an increase in farmers' income (up to 70 $ year−1) since it avoids buying synthetic fertilizer. Finally, the implementation of a vermifilter for the post-treatment and agricultural reuse of digestate from low-tech digesters showed to have both environmental and economic benefits. This technology can help to promote the circular bioeconomy in small-scale farms, reducing poverty and improving the standard of living in rural areas

Health and environmental impacts of drinking water choices in Barcelona, Spain: A modelling study

Quantitative evidence of health and environmental tradeoffs between individuals' drinking water choices is needed to inform decision-making. We evaluated health and environmental impacts of drinking water choices using health impact and life cycle assessment (HIA, LCA) methodologies applied to data from Barcelona, Spain. We estimated the health and environmental impacts of four drinking water scenarios for the Barcelona population: 1) currently observed drinking water sources; a complete shift to 2) tap water; 3) bottled water; or 4) filtered tap water. We estimated the local bladder cancer incidence attributable to trihalomethane (THM) exposure, based on survey data on drinking water sources, THM levels, published exposure-response functions, and disability-adjusted life years (DALYs) from the Global Burden of Disease 2017. We estimated the environmental impacts (species lost/year, and resources use) from waste generation and disposal, use of electricity, chemicals, and plastic to produce tap or bottled drinking water using LCA. The scenario where the entire population consumed tap water yielded the lowest environmental impact on ecosystems and resources, while the scenario where the entire population drank bottled water yielded the highest impacts (1400 and 3500 times higher for species lost and resource use, respectively). Meeting drinking water needs using bottled or filtered tap water led to the lowest bladder cancer DALYs (respectively, 140 and 9 times lower than using tap water) in the Barcelona population. Our study provides the first attempt to integrate HIA and LCA to compare health and environmental impacts of individual water consumption choices. Our results suggest that the sustainability gain from consuming water from public supply relative to bottled water may exceed the reduced risk of bladder cancer due to THM exposure from consuming bottled water in Barcelona. Our analysis highlights several critical data gaps and methodological challenges in quantifying integrated health and environmental impacts of drinking water choices

Life cycle assessment of microalgae systems for wastewater treatment and bioproducts recovery: Natural pigments, biofertilizer and biogas

The aim of this study was to assess the potential environmental impacts associated with microalgae systems for wastewater treatment and bioproducts recovery. In this sense, a Life Cycle Assessment was carried out evaluating two systems treating i) urban wastewater and ii) industrial wastewater (from a food industry), with the recovery of bioproducts (i.e. natural pigments and biofertilizer) and bioenergy (i.e. biogas). Additionally, both alternatives were compared to iii) a conventional system using a standard growth medium for microalgae cultivation in order to show the potential benefits of using wastewater compared to typical cultivation approaches. The results indicated that the system treating industrial wastewater with unialgal culture had lower environmental impacts than the system treating urban wastewater with mixed cultures. Bioproducts recovery from microalgae wastewater treatment systems can reduce the environmental impacts up to 5 times compared to a conventional system using a standard growth medium. This was mainly due to the lower chemicals consumption for microalgae cultivation. Food-industry effluent showed to be the most promising scenario for bioproducts recovery from microalgae treating wastewater, because of its better quality compared to urban wastewater which also allows the cultivation of a single microalgae species. In conclusion, microalgae wastewater treatment systems are a promising solution not only for wastewater treatment but also to boost the circular bioeconomy in the water sector through microalgae-based product recovery

Fate of priority pharmaceuticals and their main metabolites and transformation products in microalgae-based wastewater treatment systems

The present study evaluates the removal capacity of two high rate algae ponds (HRAPs) to eliminate 12 pharmaceuticals (PhACs) and 26 of their corresponding main metabolites and transformation products. The efficiency of these ponds, operating with and without primary treatment, was compared in order to study their capacity under the best performance conditions (highest solar irradiance). Concentrations of all the target compounds were determined in both water and biomass samples. Removal rates ranged from moderate (40–60 %) to high (>60 %) for most of them, with the exception of the psychiatric drugs carbamazepine, the β-blocking agent metoprolol and its metabolite, metoprolol acid. O-desmethylvenlafaxine, despite its very low biodegradability in conventional wastewater treatment plants, was removed to certain extent (13–39 %). Biomass concentrations suggested that bioadsorption/bioaccumulation to microalgae biomass was decisive regarding the elimination of non-biodegradable compounds such as venlafaxine and its main metabolites. HRAP treatment with and without primary treatment did not yield significant differences in terms of PhACs removal efficiency. The implementation of HRAPs as secondary treatment is a feasible alternative to CAS in terms of overall wastewater treatment, including organic micropollutants, with generally higher removal performances and implying a green, low-cost and more sustainable technology.This research was funded by the Spanish Ministry of Economy and Competitiveness (FOTOBIOGAS Project CTQ2014-57293-C3-3-R) and the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 676070 (SuPER-W). This communication reflects only the author’s view and the Research Executive Agency of the EU is not responsible for any use that may be made of the information it contains. M.J. García-Galán and L.H.M.L.M. Santos acknowledges their Juan de la Cierva research grants (FJCI-2014-22767 and IJCI-2017-34601, and IJCI-2017-32747, respectively), and M. Garfí and S. Rodríguez-Mozaz thanks the Ramon y Cajal program (RYC-2016-20059 and RYC-2014-16707, respectively), all from the Spanish Ministry of Economy and Competitiveness

Constructed wetlands operated as bioelectrochemical systems for the removal of organic micropollutants

The removal of organic micropollutants (OMPs) has been investigated in constructed wetlands (CWs) operated as bioelectrochemical systems (BES). The operation of CWs as BES (CW-BES), either in the form of microbial fuel cells (MFC) or microbial electrolysis cells (MEC), has only been investigated in recent years. The presented experiment used CW meso-scale systems applying a realistic horizontal flow regime and continuous feeding of real urban wastewater spiked with four OMPs (pharmaceuticals), namely carbamazepine (CBZ), diclofenac (DCF), ibuprofen (IBU) and naproxen (NPX). The study evaluated the removal efficiency of conventional CW systems (CW-control) as well as CW systems operated as closed-circuit MFCs (CW-MFCs) and MECs (CW-MECs). Although a few positive trends were identified for the CW-BES compared to the CW-control (higher average CBZ, DCF and NPX removal by 10-17% in CW-MEC and 5% in CW-MFC), these proved to be not statistically significantly different. Mesoscale experiments with real wastewater could thus not confirm earlier positive effects of CW-BES found under strictly controlled laboratory conditions with synthetic wastewaters.Comment: Chemosphere, 38 pages, 1 figure, 4 tables (2 figures and 6 tables in Supplementary Information

Behavior of UV Filters, UV Blockers and Pharmaceuticals in High Rate Algal Ponds Treating Urban Wastewater

The present study evaluated the efficiency of a high rate algal pond (HRAP) at pilot scale to remove pharmaceuticals and personal care products (PPCPs) from urban wastewater, including UV-filters and parabens (10), benzotriazoles (4), antibiotics (15), anti-inflammatories (3) and other pharmaceuticals (3). A total of 35 compounds were targeted, of which 21 were detected in the influent wastewater to the HRAP. Removals (RE%) for pharmaceuticals were variable, with efficient eliminations for atenolol (84%) and sulfathiazole (100%), whereas the anti-inflammatories naproxen and ketoprofen were only partially removed <50%. Benzotriazoles showed elimination rates similar to those of conventional WWTPs, with RE% ranging from no elimination to 51% for the UV filter benzophenone-3 (BP3) and 100% for 4-methylbenzilidenecamphor (4MBC). Hazard quotients (HQs) were estimated for those compounds not fully eliminated in the HRAP, as well as the cumulative ecotoxicity in the resulting effluent. The majority of the compounds yielded HQs < 0.1, meaning that no environmental risk would be derived from their discharge. Overall, these results clearly indicate that HRAPs are a reliable, green and cost-effective alternative to intensive wastewater treatment, yielding promising results removing these contaminants.M.J. García-Galán and M. Garfí would like to thank the Spanish Ministry of Economy and Competitiveness for their research grants (IJCI-2017-34601 and RYC-2016-20059, respectively). Lucas Vassalle would like to acknowledge the National Council for Scientific and Technological Development from Brazilian Ministry of Education—CNPQ (scholarship 204026/2018-0). Larissa T. Arashiro is grateful to the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 676070 (SuPER-W). This communication reflects only the author’s view and the Research Executive Agency of the EU is not responsible for any use that may be made of the information it contains. The authors would like to thank Antonio Ortiz Ruiz for his help on the design of Figure 1.Peer reviewe