Effect of air temperature and aeration strategy on water removal during sewage sludge composting

Water removal is one of the main objectives of sewage sludge composting to reduce the volume and mass of sewage sludge. In this study, the effect of aeration strategy and ambient temperature (summer and winter) on composting pile temperature, moisture content, and volatile solid (VS) change were studied during sewage sludge composting processes in a well-operated sludge composting plant. The results showed that the temperatures of the composting pile could remain above 55°C for more than 3 days under all conditions, which was sufficient to meet the requirement of harmless treatment. Moisture content of composting material decreased from 65%–69% to 39.2%–52.6% within 20 days, and VS decreased to about 77%. In the end of the composting process, cumulative water removal was 0.45–0.47?kg/kg in summer, which was significantly higher than that in winter (0.35–0.36?kg/kg). When the average aeration rate was fixed, aeration strategy with a smaller aeration rate and higher on/off time ratio showed more water removal than that with a higher aeration rate and lower on/off time ratio in summer, but showed reverse results in winter.     

Properties evaluation and fabrication of green clay reformulated from water sludge

Water sludge from Sungai Dua Penang fresh water processing plant has been successfully converted into functional pottery clay with improved physicochemical behavior and properties. Water sludge was generally made of kaolinite mineral that consisted of silica and alumina. At 7 h of milling duration, water sludge demonstrated a narrow particle size distribution at the size range of 107–150 µm. Water sludge owned a specific surface area of 27 m²/g with 8.8 nm (diameter) pore size and 0.05 cm³/g pore volume. Plasticity of clay body increased when clay formulation involved fine particles, e.g. water sludge or bentonite, which promote water adsorption ability. Fine particles with large surface area and better compaction also explained the enhanced hardness of pottery clay. The incorporation of clay minerals such as bentonite and sodium silicate into the formulation has facilitated metals immobilization within the clay body. Final clay product has a terra cotta color and performed a uniform shrinkage without obvious fracture. The fabrication of pottery wares from water sludge with minimized metals leakage has not only higher reutilize value but also a cost effective green method for handling waste and environmental issues.     

热解温度对污泥生物炭稳定性及养分淋溶特性影响

以市政污泥为原料,在300、500、700 ℃ 条件下热解制备得到污泥生物炭。采用碱液吸收法测定生物炭在培养环境下的CO₂释放速率以表征其降解速率,并采用预测模型计算得到生物炭的半衰期。以去离子水为浸提剂考察了生物炭中可溶性养分含量及其淋溶特性。结果表明:在300~700℃范围内,较高温度下制备的生物炭降解缓慢,稳定性更强,可在自然环境中长期存在,具有更好的固碳效果;较低温度下制备的生物炭中水溶性氮、水溶性钾含量更高,但水溶性磷含量更低;生物炭中养分的淋溶效果与其可溶性养分含量一致,较低温度下制备的生物炭的淋溶液中水溶性氮、水溶性钾含量较高,水溶性磷含量较低。     

利用电镀酸铜废渣修复碱铜阳极的方法

以9 mol/L硫酸溶解某电镀公司废水处理所产生的酸铜渣(含铜35%~43%),将所得含铜溶液经过滤后作为电解液,采用电解法修复作为阴极的破损碱铜阳极,探讨了阳极类型,电流密度,镀液中硫酸和铜离子含量,以及温度对铜沉积速率的影响。分析了阳极修复前后的纯度和孔隙度,并通过赫尔槽试验对比了修复后的阳极与完好阳极的性能。结果表明,修复后的阳极虽然孔隙度分布不均,但是能够满足碱铜电镀的需要,为处置含铜浓废液、含铜泥渣提供了新的思路。     

Enhanced biological nutrient removal in modified carbon source division anaerobic anoxic oxic process with return activated sludge pre-concentration☆

A pilot-scale modified carbon source division anaerobic anoxic oxic (AAO) process with pre-concentration of returned activated sludge (RAS) was proposed in this study for the enhanced biological nutrient removal (BNR) of municipal wastewater with limited carbon source. The influent carbon source was fed in step while a novel RAS pre-concentration tank was adopted to improve BNR efficiency, and the effects of an influent carbon source distribution ratio and a RAS pre-concentration ratio were investigated. The results show that the removal efficiency of TN is mainly influenced by the carbon source distribution ratio while the TP removal relies on the RAS pre-concentration ratio. The optimum carbon source distribution ratio and RAS pre-concentration ratio are 60%and 50%, respectively, with an inner recycling ratio of 100%under the optimum steady operation of pilot test, reaching an average effluent TN concentration of 9.8 mg·L?1 with a removal efficiency of 63%and an average TP removal efficiency of 94%. The mechanism of nutrient removal is discussed and the kinetics is analyzed. The results reveal that the optimal carbon source distribution ratio provides sufficient denitrifying carbon source to each anoxic phase, reducing nitrate accumulation while the RAS pre-concentration ratio improves the condition of anaerobic zone to ensure the phosphorus release due to less nitrate in the returned sludge. Therefore, nitrifying bacteria, denitrifying bacteria and phosphorus accumulation organisms play an important role under the optimum condition, enhancing the performance of nutrient removal in this test.     

焦化废水处理中斜板沉淀池翻泥原因及解决措施

该文以某焦化厂废水水处理系统物化段为研究对象,对斜板沉淀池的翻泥现象进行分析。结果表明通过改变沉淀池的配水方式及增加压缩空气搅拌等措施,有效地解决了翻泥的问题,保障了生产的稳定性。     

高温热水解预处理技术用于污泥减量化及资源化的应用

该文介绍了高温热水解预处理技术应用于广州市四间污水厂污泥,通过运行调试得到最佳工艺参数。在最优工况下,各厂污泥有机质降解率均达40%以上,水解后污泥经板框压滤脱水含水率稳定在40%以下,污泥残渣用于制作植草砖。     

好氧饥饿对膨胀污泥硝化性能及污泥特性的影响

采用SBR好/缺氧工艺,考察了好氧饥饿对于丝状菌膨胀污泥中硝化细菌活性及污泥性能的影响。结果表明,14 d的好氧饥饿过程(无外加底物,保持曝气)中,氨氧化细菌(ammonia-oxidizing bacteria, AOB)表现出更高的饥饿敏感性,其好氧衰减速率[(0.42±0.06)d^-1)高于亚硝酸盐氧化菌(nitrite-oxidizing bacteria, NOB)的好氧衰减速率[(0.34±0.05)d^-1]。恢复阶段初期,系统出现了明显的亚硝酸盐积累现象,这主要归因于AOB具有在环境发生改变时做出快速反应的能力,具体体现在AOB较NOB具有更高的活性恢复速率上。此外,好氧饥饿能够快速杀死丝状细菌,迅速改善膨胀污泥的沉降性能,使污泥的SVI由170 ml·g^-1快速下降到30 ml·g^-1。胞外聚合物(extracellular polymeric substances, EPS)和溶解性微生物产物(soluble microbial products, SMP)能够相互转化,并为饥饿污泥提供一定的碳源和能源,保证了细菌在饥饿环境中长期的细胞维持。     

重金属污染河道底泥固化/稳定化研究进展

固化/稳定化技术是处理重金属污染底泥的相当有效的方法,其机理主要是通过沉淀、吸附和络合作用将重金属污染物转化为更加稳定的形态。文章在总结国内外固化/稳定化技术的基础上,简单介绍了固化/稳定化的评估方法。按固化/稳定化药剂的不同,讨论分析了水泥固化、磷酸盐稳定化、无机物混合稳定化和有机物稳定化四种方法,通过对研究成果的总结,探讨了重金属污染河道底泥固化/稳定化处理技术的发展趋势。     

絮凝技术在化工污水处理中的应用

对不同种类的絮凝剂在不同试验条件下得到的絮凝现象进行观察,絮凝后的污水通过带式压榨过滤机过滤,根据过滤前后污泥性质的变化选择出最佳的絮凝剂及使用条件。