溶菌酶和硫酸铝联用优化污泥脱水性能的研究

Optimization of the sludge dewaterability via lysozyme integrated with aluminum sulfate

以污泥沉降体积、污泥比阻和污泥泥饼含水率为指标,考察了溶菌酶和硫酸铝联用时加药方式和加药剂量对活性污泥沉降性能及脱水性能的影响。结果表明,先投加溶菌酶后投加硫酸铝时污泥的脱水性能更佳,硫酸铝和溶菌酶的最佳投加量均为0.10 g/g TS(总固体),此时,污泥泥饼含水率和污泥比阻分别可达71.84%和0.68×1012m/kg,相比于硫酸铝单独调理分别降低了约5%和0.23×1012m/kg。污泥胞外聚合物(EPS)含量分析表明,溶菌酶和硫酸铝联用时显著降低了污泥中LB-EPS(松散附着性EPS)含量,在最佳投量下可将原污泥的LB-EPS中的蛋白质和多糖依次从(13.44±2.11)mg/L和(23.97±3.44)mg/L降至(1.72±0.32)mg/L和(8.69±0.15)mg/L,表明联合处理使得EPS中的水分得到释放,提高了脱水性能。

This paper is aimed at introducing a renovated method for enhancing the sludge dewaterability via lysozyme mixed with aluminum sulfate as well as engaged in an analysis of the potential mechanism by analyzing the extracellular polymeric substances（ EPS） in the sludge. To explore the sludge properties,we have chosen the moisture content of the sludge filtration cake and its specific resistance to filtration（ SRF） as the indexes of the sludge dewaterability behavior and the 30 min sludge settling volume as the index of the sludge settleablllity. What is more,we have also done the experiments for treating lysozyme（ 0. 10 g/g TS） andaluminum sulfate（ 0. 10 g/g TS）,respectively,with lysozyme（ 0. 10 g/g TS） being followed by aluminum sulfate（ 0. 10 g/g TS） and aluminum sulfate（ 0. 10 g/g TS） by lysozyme（ 0. 10 g/g TS）,so as to identify and determine the effects of the dosage patterns on the sludge properties. Then we have also examined the effects of aluminum sulfate by fixing the dosage of lysozyme at0. 10 g/g TS and increasing sulfate aluminum dosage from 0 to0. 20 g/g TS at a gradient of 0. 05 g/g TS. And,then,we can manage to increase the dosage of lysozyme from 0 to 0. 20 g/g TS at a gradient of 0. 05 g/g TS. And,finally,it would be possible for us to investigate and explore the potential mechanism by extracting LB-EPS and TB-EPS in the different dosage patterns by using a modified heat-extracting method. All of the aforementioned experiments can all be categorized into the comparison and control groups for application of raw sludge to the case study samples. The results of the above experiments show that lysozyme can help to enhance the sludge dewaterability to a certain extent whereas the slightly deteriorated sludge settleablllity,and aluminum sulfate can contribute remarkably to the improvement of the sludge dewaterability and settleablllity. When lysozyme is combined with aluminum sulfate,it would be better to improve the sludge dewaterability,and settleablllity slightly deteriorates as compared with aluminum sulfate treating alone. And it is also better for the dewaterability to dose lysozyme than aluminum sulfate first. We have also found that the optimal dosage of lysozyme and aluminum sulfate has to be chosen as 0. 10 g/g TS,under which it would be possible for the sludge cake moisture content and SRF to reach a percentage of 71. 84% and 0. 68 × 1012m/kg,respectively. Moreover,as compared with that of the sludge treated with aluminum sulfate alone,the moisture content and SRF can be reduced by about 5% and 0. 23 × 1012m/kg,respectively. Furthermore,the analysis of EPS content in the sludge indicates that EPS of sludge treated with lysozyme has been found much higher due to the hydrolysis of the cell walls with some substances released from the cells. Further tests prove that,when treated with aluminum sulfate,dramatic reduction of EPS can be found in the sludge,especially,that of LB-EPS,which serves as an important factor to improve the sludge dewaterability,and settleablllity.Moreover,the remarkable decrease of LB-EPS can be found after the coupling dosage of lysozyme and aluminum sulfate. As a result,the protein and polysaccharide in LB-EPS can be reduced from（ 13. 44 ± 2. 11） mg/L and（ 23. 97 ± 3. 44） mg/L to（ 1. 72± 0. 32） mg/L and（ 8. 69 ± 0. 15） mg/L at the optimum dosages of lysozyme and aluminum sulfate. This signifies that the combined treatment is entitled with the advantages of lysozyme and aluminum sulfate to be able to promote the sludge dewaterability.