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Investigations of nutrient removal from farmers settlement wastewater treatment facilities using mineral filter
Date Issued |
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2006 |
Highly polluted wastewater is formed on private farms. The wastewater contains N and P concentrations up to 150 mg l-1 and 30 mg l-1 respectively, which is 2–3 times higher than that contained in domestic wastewater. During the biological treatment of wastewater the removal of organic pollutants (BOD5 and SS) is about 96 % and the treatment efficiency satisfies the environment protection standards. However, the removal of biogenic pollutants is only 55%, thus the residual pollution with biogenic substances exceeds the maximum allowable rate according to N and P for wastewater released into the environment. Currently, different natural and artificial powdery mineral materials (zeolite, filtralite, etc.) containing metals and carbon compounds are transported into Lithuania. Such materials could be used as P and N adsorbing filters. In respect of the filter load with pollutants, biologically pre-treated wastewater treatment efficiency of N and P was determined to be from 45 to 93% and from 20 to 78% respectively. Having filtrated the wastewater through a filter containing 50% of zeolite and 50% of filtralite, N and P removal efficiency was fluctuating from 18 to 65% and from 51 to 92% respectively. Having made the investigations with different loads of minerals, it was determined that N removal is more efficient in the zeolite mineral filter, while P removal is more efficient in the filtralite filter. In order to reach the best results of biogenic pollution removal, both mineral mixtures should be used for the load of the filter.