ANAEROBIC CODIGESTION OF AGRICULTURAL INDUSTRIES WASTEWATERS

Wastewaters generated from agricultural industries are usually hard to treat due to a high organic content. The basic treatment process to b e used can only be anaerobic digestion, a process with the additional advantages of (i) limited production of stabilized sludge and (ii) uti lization of the produced biogas. The cotreatment of such seasonally pr oduced wastewaters is proposed in order to secure the economically fav orable and stable year-round operation of a treatment plant, with the additional benefits of smaller capital costs (due to the use of centra lly located rather than distributed treatment facilities) and the expl oitation of complementarity in waste characteristics (e.g. avoidance o f nutrients (N,P) addition when a codigested wastewater contains nutri ents in excess). A mathematical model for codigesting piggery, olive-m ill and dairy wastewaters was developed based on batch kinetic experim ents. An organic loading rate of 3.84 g COD/l-d was found to be safe f or a digester operating on a year-round basis, fed sequentially with p iggery, piggery-olive-mill and piggery-dairy wastewaters. Copyright (C ) 1996 IAWQ. Published by Elsevier Science Ltd.