Comparison of Three Systems for Biological Greywater Treatment

• Published in: Water (Basel) 2010-06, Vol.2 (2), p.155-169
• Main Authors: Hernandez Leal, L, Temmink, B.G, Zeeman, G, Buisman, C.J.N
• Format: Article
• Language: English
• Subjects: Chemical oxygen demand; Environmental Technology; Milieutechnologie; Particle size; Reactors; Sectie Milieutechnologie; Sludge; Sub-department of Environmental Technology; Surfactants; Toilet facilities; WIMEK
• ISSN: 2073-4441; 2073-4441
• DOI: 10.3390/w2020155

Greywater consists of household wastewater excluding toilet discharges. Three systems were compared for the biological treatment of greywater at a similar hydraulic retention time of approximately 12–13 hours. These systems were aerobic treatment in a sequencing batch reactor, anaerobic treatment in an up-flow anaerobic blanket reactor and combined anaerobic-aerobic treatment (up-flow anaerobic blanket reactor + sequencing batch reactor). Aerobic conditions resulted in a COD removal of 90%, which was significantly higher than 51% removal by anaerobic treatment. The low removal in the anaerobic reactor may have been caused by high concentration of anionic surfactants in the influent (43.5 mg/L) and a poor removal of the colloidal fraction of the COD in up-flow anaerobic sludge blanket reactors. Combined aerobic-anaerobic treatment accomplished a COD removal of 89%, similar to the aerobic treatment alone. Greywater methanization was 32% for the anaerobic system and 25% for the anaerobic-aerobic system, yielding a small amount of energy. Therefore, anaerobic pre-treatment is not feasible and an aerobic system is preferred for the treatment of greywater.