Sustainability of decentralized wastewater treatment technologies

Abstract

In many Countries, small communities are required to treat wastewater discharges to increasing standards of lesser environmental impacts, but must achieve that goal at locally sustainable costs. While biological membrane treatment (membrane bio-reactors (MBRs)) is quickly becoming the industry standard for centralized wastewater treatment plants, and would also be ideally suited also for small plants potentially subject to relatively large hydraulic load variations, its investment and operating costs are usually high for that class of applications. Consequently, small treatment plants are generally configured as anoxic or aerated biological tanks with little sedimentation, making them quite susceptible to hydraulic loads transient and sludge quality changes. As an alternative, Constructed Wetlands Systems (CWSs) are gradually and successfully being introduced in many Countries. CWSs are designed to utilise the natural functions of wetland vegetation, soils and their microbiological populations to treat wastewater. Pretreatment occurs by filtration and settling, followed by bacterial decomposition in a natural-looking lined marsh. A new technology, a new type of membrane-like aerobic reactor initially designed for the degradation of hydrocarbon-derived groundwater contaminants, was recently tested for treating domestic, with performance similar to that of MBRs. Examples from the above applications are illustrated and compared in this paper. The paper also discusses merits and drawbacks of the various illustrated technologies, in view of their sustainability potential, and according to the new development paradigms for urban water systems, that encourage the development of local water-cycle clusters with local reuse and recycle of the resource, and possible local recovery of energy and/or materials.

Integrated, Decentralized Wastewater Management for Resource Recovery in Rural and Peri-Urban Areas

“…In the EU, about 30% of the population of former CEE (Central and Easter European) countries (42 million people) lives in settlements of less than 2000, while this percentage is lower than 20% in the western part [1]. Many other areas of the world show a still preponderantly rural or peri-urban (settlements in proximity of a large urban areas, but without the services and facilities proper of such areas) character.…”

The Potential Phosphorus Crisis: Resource Conservation and Possible Escape Technologies: A Review

“…For this reason, at present, much effort is being devoted to the removal of N & P from wastewater discharges, especially in low exchange water bodies [34][35][36], as foreseen by current environmental protection regulations (in the EU, the Water Framework Directive, WFD). Such removal can occur both with physicochemical and biological processes [37,38] however, is it costly and perhaps not completely necessary in view of the new paradigms on wastewater management, stressing resource recovery according to circular economy principles [39][40][41].…”

Experimental Application of an Advanced Separation Process for NOM Removal from Surface Drinking Water Supply

“…NOM-related issues can raise to significant proportions in view of the current water use paradigms, promoting local recycling and reuse of wastewater [16][17][18]. More frequently wastewater could (will) be treated to discharge standards, temporarily stored in surface or ground water reservoirs [19], and abstracted later for water supply purposes, pending additional treatment [20].…”