Study On Treatment Of Swine Wastewater With Bioflocculant

The swine water is one of typical wastewater include high concentration of organic matter, high concentration ofN,P,K and amounts of harmful microorganism, the treated wastewater was allowed to enter into the environment. Flocculation is an effective method of removing suspended solids in wastewater treatment. The chemical flocculants have been widely used for their effective flocculating and low cost, but they have threatened human health and increased environmental risk. Compared with conventional chemical flocculants, bio flocculants are high-effective, harmless ness and lack of secondary pollution; therefore bio flocculants have gained much wider attention and research to date in recent years.Two novel bioflocculant-producing strains and two novel compound bioflocculant-producing bacterium were isolated from active sludge and anaerobic wastewater from local hoggery (Zhengzhou, China), and it was named xn17, xnl2, xn10+xn9, xn11+xn7, respectively. The xn17 was actinomyces stains, the others were bacteria strains. The flocculating activity of xnl7, xnl2, xn10+xn9,xn11+xn7 reached over 95%while the optimal cultivating condition as follows:initial pH 5 (except xn12 and xnll+xn7,5-6); inoculum sizes (per 50 mL culture medium) 0.5 mL,1 mL, 0.6 mL,0.6 mL, respectively; shaking speed 150 rpm, culture temperature 30℃, culture time 1.5-2.5 d,3-4.5 d,3.5-4.5 d,3-4.5 d. The color reaction results of polysaccharide and protein was showed that their composition mainly was the polysaccharide and no protein, and xnl7, xn12, xn10+xn9, xnll+xn7 had strong thermal stability, their flocculating activity were obviously affected by pH of wastewater, their flocculating activity reached over 80% in the pH range of 2-8,2-6,2, 2, respectively. Compared to other cautions, Ca2+ and Al3+ had an obvious aid-flocculation effect. Their flocculating activity reached max in the following condition:1% CaCl2 dosage of 1.5 mL,2 mL,3 mL,1 mL, respectively; the dosage of xn17, xn12, xn10+xn9, xn11+xn7 1.5 mL,2 mL,3 mL,1 mL, respectively.In real wastewater application, from these factor (pH, CaCl2 dosage, bioflocculant dosage) trends, the pH is the most significant to the removing rate of turbidity; the effecting trend was different between the CaCl2 dosage and the bioflocculant dosage. The optimal flocculating condition of xn17, xn12, xn10+xn9, xn11+xn7 as follow:xn17, xn12, xn10+xn9, xn11+xn7 (per 200 mL waste water):pH 9.5-11,9-11,9-10,10-11 respectively; the bioflocculant dosage:1-6 mL,2-4 mL, 2-4mL,2-6 mL, respectively; the 1% CaCl2 dosage 2mL, at this moment, their removing rate of turbidity was 70%-86.73%. The collaborative effect was considered between pH and Ca2+, instead of solution of NaOH, saturated solution of CaO was used to adjust pH values that could enhance treated effect in waste water application. The removing rate of turbidity (xn17, xn12, xn10+xn9) was 81.85%-95.56%, the removing rate of COD was below 50% while the optimal saturated solution dosage of CaO (per 100 mL wastewater) was 10-12 mL,8-12 mL,6-12 mL,8-12 mL, respectively. Obviously, its flocculating effect is better than that with NaOH. For the united application of bioflocculant, while the condition (per 100 mL wastewater) as follows:the bio flocculating dosage 0.5 mL, the 1%CaCl2 dosage 0.5 mL, the saturated solution of CaO 5 mL, the PAC dosage was 0.5-4 mL,1-3 mL,3-4 mL,1-4 mL, respectively, the xn17, xn12, xn10+xn9, xnll+xn7 removal rate of turbidity was 80.93%-92.03%; their removal rate of COD was below 50%. Therefore, the combination of bioflocculant and PAC could bring more wide methods for bioflocculant application. The united application of bioflocculant and PAC was better than PAC alone.