Erratum to: Bioprocess Biosyst Eng DOI 10.1007/s00449-011-0528-9

Erratum to the conclusion section

Accordingly, it is recommended to operate such a system at an HRT not exceeding 5.8 h and OLR of 3.6 kg COD/m3 day for producing an effluent quality complying for reuse in unrestricted irrigation purposes [39].

39. Tawfik A, Abdel Wahaab R, Al-Asmer A, Matary F (2011) Optimization of down-flow hanging sponge (DHS) system treating grey wastewater for reuse in irrigation purposes. Int J Sustain Water Environ Syst 3(1):13–18