Purifying percolation water from tip esp. acid water from fresh tip - by chemical treatment to lower content calcium, magnesium and heavy metals, and anaerobic purification

摘要

In purification of percolation water from rubbish tips, esp. acid percolation water from relatively fresh tips, the water is collected, and is (a) conditioned chemically to lower the content of Ca, Mg and heavy metals, (b) fed to an anaerobic purification step, and opt. (c) fed to a hyperfiltration step. Pref. (a) the pH of the water is raised to at least 8 (8-10) (using NaOH or milk of lime), causing pptn. of Ca, Mg and heavy metals, the pptes. are allowed to settle, and the pH of the water. Conditioning is at 30-40 deg.C, and a flocculant, esp. an anionic flocculant, may be used to promote settling. (b) an upflow Anaerobic Sludge Bed (UASB) reactor is used for the anaerobic purification. Anaerobic purification is at 20-40 (30-38) deg.C and (part of) the P removed in the chemical conditioning may be made up before/during the anaerobic purification. Energy for the process is provided by CH4 from a stabilised rubbish tip, opt. made up with biogas from the anaerobic purification step.