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Treatment of municipal wastewaters with aerobic granular sludge (AGS) has been extensively researched in the past decade and has now become a mature option for implementation. Aerobic granules are distinguished from activated sludge flocs through their larger size and more compact and spherical structure. Due to these properties, granules settle rapidly and can therefore contribute to compact treatment processes through high sludge concentrations and short settling times. In this review, the factors that promote granulation in treatment processes are identified and discussed and the experience of municipal wastewater treatment with AGS at laboratory-, pilot-, and full-scale are critically evaluated. The most important factors to promote granulation include exposing the biomass to relatively high concentrations of contaminants in sequencing batch reactors, promoting slow-growing microorganisms and applying a relatively short settling time. Enhanced biological phosphorus removal is preferably integrated with AGS and the large size of the granules makes simultaneous nitrification (at the surface of the granules) and denitrification (at the inner, anoxic parts) feasible. We propose directions for future research including further optimization of AGS to obtain stable and low effluent nutrient concentrations in line with increasingly stringent upcoming effluent demands. [ABSTRACT FROM AUTHOR]

Historically, municipal solid waste landfills have been designed and operated as disposal facilities with suboptimal degradation under anaerobic conditions, resulting in slow waste stabilization and generation of landfill gas rich in methane and high strength leachate. Recently, aerobic bioreactor landfilling is being promoted as a promising method that enhances waste stabilization while producing a relatively weaker leachate and no methane generation. The authors review transformation processes and benefits associated with aerobic bioreactor landfilling. Factors affecting the operation of aerobic bioreactor landfills were detailed and performance indicators were defined with technical and operational considerations. The article emphasizes conditions for economic viability of the technology and concludes with outlining existing gaps and future research needs to improve the understanding and performance of aerobic bioreactor landfilling. [ABSTRACT FROM PUBLISHER]

This review aims to discern a treatment for grey water by examining grey water characteristics, reuse standards, technology performance and costs. The review reveals that the systems for treating grey water, whatever its quality, should consist of processes that are able to trap pollutants with a small particle size and convert organic matter to mineralized compounds. For efficient, simple and affordable treatment of grey water with safe effluent reuse, a combined anaerobic-aerobic process is recommended, with disinfection being an optional step. The removal and subsequent conversion of suspended and colloidal particles in the anaerobic process need further improvement. Furthermore, the reuse standards should be revised and classified considering the reuse options and requirements. [ABSTRACT FROM AUTHOR]