Advanced compact wastewater treatment based on coagulation and moving bed biofilm processes

Advanced compact wastewater treatment processes are being looked for by cit ies all over the world as affluent standards are becoming more stringent an d land available for treatment plants more scarce. In this paper it is demo nstrated that a very substantial portion of the pollutants in municipal was tewater appears as particulate and colloidal matter. Pre-coagulation, there fore, gives very efficient pretreatment that results in considerable saving in the total space required by the plant, especially when combined with a biofilm process for the removal of the soluble matter. A new biofilm proces s for this purpose is described. The moving bed biofilm process is based on plastic carriers, that move in the reactor, on which biomass attach and gr ow. The carriers are kept within the reactor by a sieve arrangement and bio mass that is sloughing off the carriers is separated before effluent discha rge. In addition to combining the moving bed biofilm process with pre-coagu lation, the paper discusses also the use of a high-rate moving bed process combined with coagulation directly after the biofilm reactor in order to en hance separability. This results in very compact treatment plants for secon dary treatment and possibly phosphate removal.