Purification by activated sludge

Purification by activated sludge with residence time of ten to 24 hours and a sludge mass of advanced age has a buffer effect which allows  

It generally involves water which, after physicochemical treatment, still exhibits a BOD5 of at least 100 mg l i.e. that may be equivalent to production of at least 40 to 50 mg l of activated sludge. 

Progress in engineering and implementation technology for this process in the past ten years has found answers to most of these objections  

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