Reduction of pathogens in greywater with biological and sustainable treatments selected through a multicriteria approach.

Non-potable reuse of greywater (GW) can represent a valid alternative to freshwater consumption, satisfying the Sustainable Development Goals promoted by United Nations. The Multi-Criteria Analysis (MCA) was applied to select the most suitable processes for the reduction of microbiological contamination in GW. A pilot plant, including horizontal flow constructed wetland (CW) and anaerobic filtration (AF) in parallel, best treatment options according to MCA results, was built to treat GW collected from a Venezuelan family. (i) The removal efficiency of microbiological parameters, and (ii) the turbidity as possible microbiological contamination indicator and possible influence factor of disinfection treatment, were investigated. Except for Escherichia coli (4.1 ± 0.9 log reduction with AF), CW achieved the best reductions yields for total coliforms, faecal coliforms, and Salmonella, respectively equal to 3.1 ± 0.5 log, 4.3 ± 0.5 log, and 2.9 ± 0.4 log. In accordance with Venezuelan legislation and WHO guidelines, GW treated with CW was found to be suitable for irrigation reuse for non-edible crops. However, the reduction of pathogens by CW should be considered as a preliminary and not complete disinfection treatment. To reuse GW, especially in the irrigation of edible crops, stronger disinfection treatment should be considered as a complement to the preliminary disinfection performed by CW, to avoid any kind of risk. No significant correlation was found for turbidity either as a possible predictor of microbiological contamination or as an influence on biological disinfection.

Remediation of soil polluted with petroleum hydrocarbons and its reuse for agriculture: Recent progress, challenges, and perspectives.

Petroleum hydrocarbons (PHs) are used as raw materials in many industries and primary energy sources. However, excessive PHs act as soil pollutants, posing serious threats to living organisms. Various ex-situ or in-situ chemical and biological methods are applied to restore polluted soil. However, most of the chemical treatment methods are expensive, environmentally unfriendly, and sometimes inefficient. That attracts scientists and researchers to develop and select new strategists to remediate polluted soil through risk-based analysis and eco-friendly manner. This review discusses the sources of PHs, properties, distribution, transport, and fate in the environment, internal and external factors affecting the soil remediation and restoration process, and its effective re-utilization for agriculture. Bioremediation is an eco-friendly method for degrading PHs, specifically by using microorganisms. Next-generation sequencing (NGS) technologies are being used to monitor contaminated sites. Currently, these new technologies have caused a paradigm shift by giving new insights into the microbially mediated biodegradation processes by targeting rRNA are discussed concisely. The recent development of risk-based management for soil contamination and its challenges and future perspectives are also discussed. Furthermore, nanotechnology seems very promising for effective soil remediation, but its success depends on its cost-effectiveness. This review paper suggests using bio-electrochemical systems that utilize electro-chemically active microorganisms to remediate and restore polluted soil with PHs that would be eco-friendlier and help tailor-made effective and sustainable remediation technologies.

Implementation of circular economy in the management of municipal solid waste in an Italian medium-sized city: A 30-years lasting history.

The Circular Economy model is gaining attention as a key factor for boosting sustainable development. Reducing the consumption of raw materials, as well as increasing the amount of recycled waste, are the current challenges the municipal solid waste management system is called for. In this study, the evolution of the municipal waste management strategies in the city of Brescia was analysed, covering a period of 30 years. The results obtained by a) progressively extending the separate collection with street containers, b) building a Waste to Energy plant, and c) moving to a door to door collection system, were assessed via numerical indicators and mass balances. In order to highlight the complexity of the system, the waste flow, from collection to the achievement of the "end of waste" attribute, was followed. Separate collection with street containers came to a saturation percentage around 40%. The realization of the incineration plant eliminated the direct disposal of waste to landfills. With the introduction of the new collection system, the separately collected waste increased up to over 73%, the per capita amount of collected waste decreased from 685.3 kg/(in y) to 579.6 kg/(in y), and a significant reduction of recyclable materials in the unsorted waste was gained. In the paper, these achievements and their affecting factors are analysed. Moreover, criticalities in the calculation of material recovery indices due to the complexity of the system (72 transformation sites were identified) are discussed.

Horizontal Flow Constructed Wetland for Greywater Treatment and Reuse: An Experimental Case.

In the coming years, water stress is destined to worsen considering that the consumption of water is expected to increase significantly, and climate change is expected to become more evident. Greywater (GW) has been studied as an alternative water source in arid and semiarid zones. Although there is no single optimal solution in order to treat GW, constructed wetlands proved to be effective. In this paper, the results of the treatment of a real GW by a horizontal flow constructed wetland (HFCW) for more than four months are shown. In the preliminary laboratory-scale plant, Phragmites australis, Carex oshimensis and Cyperus papyrus were tested separately and showed very similar results. In the second phase, pilot-scale tests were conducted to confirm the performance at a larger scale and evaluate the influence of hydraulic retention time, obtaining very high removal yields on turbidity (>92%), total suspended solids (TSS) (>85%), chemical oxygen demand (COD) (>89%), and five-day biological oxygen demand (BOD5) (>88%). Based on the results of the pilot-scale HFCW, a comparison with international recommendations by World Health Organization and European Union is discussed.