Investigations on p-removal processes from wastewater applying mineral filters

Abstract

In the process of biological wostewater treatment, P-removal is efficient enough when the concentration of organic pollutants according BOD (biochemical oxygen demand) is no higher than 190 mg 1'1 of 0; and its relationship with phosphorus does not exceed 20. Hoving studied the composition ofwastewater from dairy farms itwas determined thatwastewater pollution according to BOD; is from KM) lo 900 mg I-' of 0, and the ratio of BOD/P^y is 30-36. The paper gives the results of the tests on P-removal from wastewater carried out in a laboratory model. During the investigations wastewater was flowing via mineral filters (filtralite P (FLP), zeolite (CE), and shulgite (SG)1. Total amount of Ca, Fe and Al oxides contained in those filters were 23.0,16.1 and 7.9% respectively. The rates of P-removal from wastewater in the filters were as follows: 88.5% (FLP), 45.5% (CE), and 96.3% (SG). Considering different hydraulic load, P-mass balance was calculated. The calculation results showed the following P absorption amounts: FLP - 5.08 g d-1 CE -1.76 g d-1 and SG - 3.91 g d-1 (calculated for 1 m3 of each filter). Wastewater filtration through mineral media resulted in the removal of other pollutants, too: organic pollutants removal (according to (M il ),1 was 30.8 to 72.5%, and the removal of nitrogen compounds (more than 90% of which were in the form of ammonium salts) was even 93.2% in CE filter.