稻秸秆制备微生物絮凝剂及改善污泥脱水性能的研究

采用水稻秸秆制备微生物絮凝剂，研究了微生物絮凝剂对污泥脱水性能的影响，并通过响应面分析法优化了微生物絮凝剂与聚合氯化铝（Polyaluminum chloride，PAC）复配改善污泥脱水性能的过程.结果表明，制备微生物絮凝剂的最佳条件为：800mL蒸馏水、200mL水稻秸秆酸解液、4g K₂HPO₄、2g KH₂PO₄、0.2g MgSO₄、0.1g NaCl、2g尿素，在此条件下，微生物絮凝剂产量达0.96g/L.保持原污泥pH值，当微生物絮凝剂投加量为12mg/L，干污泥量（DS）较原污泥提高了59.5%，污泥比阻（SRF）降低了53.6%，表明经微生物絮凝剂絮凝处理，污泥脱水性能显著改善.保持原污泥pH值，当PAC投加量为3g/L，干污泥量（DS）为16.4%，高于原污泥的13.2%，污泥比阻为（SRF）5.4×10¹²m/kg，低于原污泥的11.3×10¹²m/kg，说明PAC对污泥脱水性能有着明显的改善作用.响应面分析结果显示，污泥脱水最佳条件为微生物絮凝剂8.1mg/L、PAC 1.9g/L、pH值8.0，相应DS和SRF分别为24.1%和3.0×10¹²m/kg.实际污泥脱水工程中，污泥pH往往不进行调节，保持原污泥pH=6.4条件下，DS和SRF分别为23.6%和3.2×10¹²m/kg，均优于单独采用微生物絮凝剂和PAC时的污泥脱水效果.

Production of a bioflocculant by using rice stover and its performance in the improvement of sludge dewatering

A bioflocculant was produced by using rice stover, and its performance in the improvement of sludge dewatering was investigated, further, response surface methodology (RSM) was employed to optimize the treatment of sludge dewatering by the composite of the bioflocculant and Polyaluminum chloride (PAC). Optimal culture conditions for bioflocculant production were determined as 4g K₂HPO₄, 2g KH₂PO₄, 0.2g MgSO₄, 0.1g NaCl, and 2g urea dissolved in a mixture of 800mL distilled water and 200mL rice stover acid hydrolyzate, and the corresponding bioflocculant yield reached 0.96g/L. Keep original pH value of the sludge, when bioflocculant dose was adjusted at 12mg/L, DS improved 59.5%, and SRF reduced 53.6%, which indicated that the sludge dewatering has been significantly improved after treated by the bioflocculant. In the same manner, when the sludge was treated by 3g/L PAC, DS increased to 16.4% and SRF decreased to 5.4×10¹²m/kg, compared to that of 13.2% and 11.3×10¹²m/kg of the original sludge, the sludge dewatering was significantly improved. Optimal conditions for sludge dewatering by the composite of the bioflocculant and PAC were bioflocculant dose of 8mg/L, PAC dose of 1.9g/L, and pH=8.0, under this optimal condition, DS and SRF appeared as 24.1% and 3.0×10¹²m/kg, respectively. From a practical standpoint, without pH adjustment, under the optimal condition of bioflocculant dose of 8.1mg/L, PAC dose of 1.9g/L, and natural pH value of 6.4, DS and SRF were 23.6% and 3.2×10¹²m/kg, respectively. The above results were better than the alone using of bioflocculant or PAC in sludge dewatering.