INVESTIGATION OF THE PROCESS OF PROCESSING LIQUID WASTE OF UREA PRODUCTION USING A BIOFILTER

Abstract

The kinetic regularities of the recycling process of liquid waste of urea on the combined filter which contains the immobilized layer of enzymes at the process of their purification from the suspended substances, dissolved nitrate anions; the effect of pH on the filtration process are investigated and established in our research. A stable positive result was obtained on the filters with layers of:
 – oak and birch, the concentration of nitrate anions decreased from 12 to 0,06 — 0,05 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 6 — 7 g/dm3. At the same time, the increased content of tannins and the natural structure of oak and birch leaves contributes to the resistance of the leaf layer to fermentation processes, helps to use such kind of filter repeatedly.
 – linden and maple leaves, the concentration of nitrate anions decreased from 12 mg/dm3 to 0,08 mg/dm3 after 80 minutes of filtration. The content of suspended solids decreased from 37 g/dm3 to 15 g/dm3 after the third use of the filter, due to increased activity of microorganisms. At the same time, the natural structure of linden and maple leaves is thin, has a biofilm that is easily destroyed and accelerates the process of natural aerobic fermentation.
 The scientific substantiation of the direction of improvement of technology of processing of liquid waste with the increased content of nitrogen is executed. A bio filtration unit on a combined filter with a layer of oak and birch leaves with the use of an immobilized layer of enzymes is proposed. The combined filter consists of a layer of gravel, sand and dry oak and/or birch leaves. The enzyme Chymotrypsin at a concentration of 0,005 g/dm3 is fed into the formed bio filter from above. After 30 minutes, liquid waste with a temperature of 10 25 °С is gradually fed into the filter over 60 — 80 minutes. The initial concentration of suspended particles in liquid waste should not exceed a concentration of 37 — 40 g/dm3. It is determined that the optimal rate of processing of liquid waste of urea production is achieved in solutions with active reaction of hydrogen ions in the range of 6,5—7,3.