Anaerobic digestion of sewage wastewaters with sludge and rumen fluid

Abstract

Anaerobic digestion was conducrcd at mesophilic (31'e) Gild thermophilic (S5"C) conditions using sewage wasteWaTers as the substrate and sludge and/or rum ell[luid as (he inoculum; with a view to optimis» biogcs production. TIre substrate and inoculum were mixed ill the ratios J: I, 1:3, and 3: i-ivolume by weight (where sludge was used) or volume by volume (where rumen fluid was usedj.At mesophilic conditions for both inocula, [111' 3: 1 substrate/inoculum mixture produced flu>most bingos ill a 24 hour period, with the rumen 1IIi.'CfUrt'producing tlu: highest yield (20 1111). A t tlierntophilir conditions thr 3:I wastewater/sludge mi.t1UJ'1'. had rile highest biogas yield (5~ ml ), whereas when rumen fluid \Vas used as inoculum. the 1:3 mixture produced the IIIOSI biogas (66 111/). The thermophilic experiments using rumen as the inoculum were repeared for a 10 day period and the 3:1 mixture achieved the mm-11I11l1l1 yield (140 1II1) faster titan rill:other twu (I:I untl 1:3 mixtures] indiC'lIlill/J ihut tlre 3:1 substrcu c/inoculurn ratio is lite best