基于半焦的污泥调质与深度浓缩脱水

Sludge conditioning for deeply concentrated dewatering of sludge by using semi-coke

半焦具有孔隙发达、比表面积大、疏水性能强、热值高等特点,采用污泥重力浓缩脱水实验法考察了半焦投加量、粒度对污泥调质与浓缩脱水效果的影响。通过扫描电镜、红外光谱等现代分析手段探讨了基于半焦的污泥调质与深度浓缩脱水的机理。结果表明,当半焦粒度≤425μm、半焦投加量为2.5 g/100 g污泥时,浓缩污泥上清液的浊度、COD、SS分别从污泥调质前的836 NTU、258.2 mg/L、630.1 mg/L降至调质后的14.8 NTU、38.2 mg/L、18.6 mg/L,达到国家污水综合排放二级标准;浓缩污泥的含水率由调质前的91.74%降至调质后83.71%;污泥静置重力浓缩过程中,经半焦调质后的污泥沉降速率明显增加,污泥在前20 min的平均沉降速率由调质前的2.49 m L/min提高至3.48 m L/min;半焦对污泥调质与深度脱水机理主要表现在半焦对污泥的吸附作用及半焦对污泥疏水性能的增强作用。可见,基于半焦的污泥调质不仅能显著地改善污泥的浓缩脱水性能,还能提高污泥的热值,为污泥的能源化利用创造了条件。

Owing to that semi-coke has special characteristics such as developed porosity,large specific surface area,strong hydrophobicity,high calorific value,it was used for sludge conditioning in order to deeply dewater from the sludge. The influences of adding amount and size distribution of semi-coke on the promoting effect were investigated by gravity concentrating method. Mechanism of sludge conditioning and deeply concentrated dewatering in the case of addition of semi-coke was discussed based on the results of SEM,FT-IR and other analysis. The obtained results indicated that when the particle size of semi-coke was less than 425 μm and the adding amount was 2. 5 g /100 g sludge,the turbidity,COD,SS of the concentrated sludge supernatant were reduced from 836 NTU,258. 2 mg / L,630. 1 mg / L to 14. 8 NTU,38. 2 mg / L,18. 6 mg / L,respectively,which reached the national integrated wastewater discharge Grade II standard. The moisture content of concentrated sludge reduced from 91. 74% to 83. 71%. The sedimentation rate of the sludge after the conditioning was obviously faster than those without conditioning. In the first 20 minutes,the average sedimentation rate of sludge increased from 2. 49 m L / min to 3. 48 m L / min. These promoting effects should be attributed to the good adsorption of sludge by the semi-coke and the enhanced hydrophobic properties of sludge due to the addition of semi-coke. Consequently,sludge conditioning by using semi-coke can not only significantly improve the deeply concentrated dewatering prosperities of the sludge,but also improve the calorific value,which can save the energy during the utilization of sludge.