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This work examined boron removal by applying a lab-scale continuous electrocoagulation process. The impact of influent pH (4, 5, 6, 7.45, and 9) and retention time (10, 25, 50, and 100 min) on the treatment process was examined. Plate-type aluminum electrodes were used. The experiments were conducted in continuous mode, and the electric current was kept constant at 5 A. The initial boron concentration was 1,000 mg L–1. The first set of experiments concerning the influence of the influent pH showed that the highest boron removal (67%) was obtained at pH = 6. This pH value was the optimal one for boron precipitation through aluminum borate formation. The increase in the duration of the process from 10 to 100 min resulted in increasing boron removal from 45% to 79%. The longer duration of the electrocoagulation process enabled higher aluminum dissolution, thus allowing the existence of a higher amount of coagulants within the reactor. Moreover, it enhanced boron precipitation because of the longer contact time between the boron ions and the coagulants. By optimizing the key parameters of the process, the continuous electrocoagulation process showed to be an effective alternative for the removal of highly concentrated boron. [ABSTRACT FROM AUTHOR]

Reuse of treated wastewater for irrigation purposes is a measure to reduce water stress and overexploitation of freshwater resources. This study aims to investigate the environmental and economic impacts of a current conventional wastewater treatment plant (WWTP) in Peschiera Borromeo (Milan, Italy), and compare possible scenarios to enable reclaimed water reuse for agriculture. Accordingly, we propose alternative disinfection methods (i.e. enhanced UV, peracetic acid) and replace conventional activated sludge (CAS) with upflow anaerobic sludge blanket (UASB) for biological treatment and use anaerobic membrane bioreactor (AnMBR) as the tertiary treatment. Life cycle assessment (LCA) and life cycle costing (LCC) were implemented on the existing full-scale wastewater treatment line and the hypothetical scenarios. In most cases, the impact categories are primarily influenced by fertilizer application and direct emissions to water (i.e. nutrients and heavy metals). The baseline scenario appears to have the largest environmental impact, except for freshwater eutrophication, human ecotoxicity and terrestrial ecotoxicity. As expected, water depletion is the most apparent impact category between the baseline and proposed scenarios. The UASB + AnMBR scenario gives relatively higher environmental benefits than the other proposed scenarios in climate change (−28%), fossil fuel depletion (−31%), mineral resource depletion (−52%), and terrestrial ecotoxicity compared to the baseline. On the other hand, the highest impact on freshwater eutrophication is also obtained by this scenario since the effluent from the anaerobic processes is rich in nutrients. Moreover, investment and operational costs vary remarkably between the scenarios, and the highest overall costs are obtained for the UASB + AnMBR line mostly due to the replacement of membrane modules (24% of the total cost). The results highlighted the importance of the life cycle approach to support decision making when considering possible upgrading scenarios in WWTPs for water reuse. • Different technologies for tertiary wastewater treatment are compared using LCA and LCC. • The proposed scenarios with water reuse provide benefits in most impact categories. • There were no significant differences observed between the disinfection by PAA or UV. • Higher environmental benefits are obtained by the UASB + AnMBR, except freshwater eutrophication. • The highest overall costs are obtained for the AnMBR process. [ABSTRACT FROM AUTHOR]