Purifying dung water from cattle stables - by homogenising, coagulating filtering, and purifying filtrate biologically and chemically and neutralising

摘要

Purificn. is of high organic material contg. dung water obtd. in large scale stabling of cattle. In a first step, dung water is homogenised under aerobic conditions, without phase separation. Homogenised dung water is treated with coagulants, pref. Al2(SO4)3 and >=1 anion-active polyelectrolyte. Solid phase obtd. is separated from liq. phase on filter presses. Liq. phase is purified in a biologically activated sludge step. Activated sludge is removed. Biologically purified filtrate water is re-purified chemically, pref. with CaO as precipitant, setting clarified water pH 10-11.5. Purified water is sepd. from solid phase and neutralised. Ppte. formed is sepd. from purified water in a further settling step. Water-consumption is minimised. Solids obtd. can be composted naturally, for use as agricultural fertilisers. Liq. phase can be used for watering fields and causes no pollution. It can be re-used for rinsing stables. Dung water contg. 1.8-8 wt. % organic material can be processed to 2 end-prods.: purified water and pressed sludge.