Disposal of waste water from cellulose pulp factory - by precipitating organic chlorine cpds. as lime sludge, biologically clearing water, and burning combined sludges

摘要

In disposing of waste water from cellulose pulp factories, (a) the waste water from the bleaching process is brought to pH 11-12 by addn. of 500-3000 mg of CaO or Ca(OH)2 w.r.t. 1 of water, (b) the ppte. (lime sludge), contg. the organic Cl substances, is sepd., opt. after addn. of 0.2-10 mg/l of anionic polyelectrolyte, (c) the waste water freed from lime sludge is led, opt. after neutralisation with an acid suitable for biological clarification, to a biological clarifier, with other waste water from the factory, and opt. with municipal waste waters, (d)the sewage sludge forming in the biological clarifier is sepd. and combined with the lime sludge, and the two sludges are dewatered pref. to 40-50% dry matter, before or after being combined, and (e) the sludge mixt. is burned, opt. after addn. of an acid-binding agent, e.g. CaO. ADVANTAGE - The waste water can be treated without difficulty in a biological clarifier, on the large scale. The residue can be disposed of safely, without harming the environment.