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随着城市化发展的不断加快,我国污水处理规模逐渐加大,而剩余污泥(WAS)作为污水处理过程的副产品,产量较大,成分复杂且难以处理。厌氧消化技术可有效降低污泥产量,并产出甲烷等生物能源,因此应用广泛[1]。然而,由于国内厌氧消化技术主要针对于含固率较低的污泥(TS<5%),通过常规厌氧消化技术产生的VFAs等可回收碳源浓度较低,难以满足反硝化碳源需求[2]。相比于传统厌氧消化技术,高固厌氧消化所需的池容较小,生物能源产出较高,弥补了传统厌氧消化的不足[3]。KARTHIKEYAN等[4]在研究厌氧发酵中生物能源回收时,将TS大于10%的污泥定义为高固污泥。当TS高于6%时,污泥的流动性减弱,黏度增大,絮体难以破解,故导致污泥水解过程受到限制,厌氧消化效率降低[5]。因此,如何促进高固污泥的水解过程成为提高消化反应效率的关键。
过硫酸钠(PS)预处理是一种高级氧化工艺(AOPs),成本低廉、使用安全、易于普及[6]。其作用机理是,在经过超声波、紫外线、还原性金属等作用下产生具有较高氧化还原电位的SO4-·,氧化裂解胞外聚合物(EPS),提高污泥水解产酸性能[7]。YANG等[8]采用过氧一硫酸盐(PMS)对污泥进行预处理,发现随着PMS投加量从0增长到0.09 g·g−1(以总悬浮固体计),VFAs产量由29.69增长至311.67 mg·g−1(以单位挥发性悬浮固体的COD计),类腐殖酸类物质在有机质中的占比也明显降低。LUO等[9]发现,铁粉活化PS可提高短链脂肪酸产量,在PS/Fe介入下,与VFAs生产相关的微生物丰度有所增加,提高了发酵液的可生化性。
本研究以污水处理厂脱水污泥(TS≥10%)为研究对象,采用成本较低的颗粒活性炭(GAC)作为PS的活化剂,以探究GAC活化PS预处理对污泥水解产酸性能的影响。本研究结果可为高固污泥厌氧消化技术的发展提供参考。
椰壳颗粒活性炭活化过硫酸钠预处理促进高固污泥水解产酸性能
Coconut shell granular carbon activated sodium persulfate pretreatment elevates the performance of hydrolysis and acid production from high-solid sludge digestion
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摘要: 为探究椰壳颗粒活性炭活化过硫酸钠(PS)预处理对高固污泥厌氧发酵水解产酸性能的影响,通过调节挥发性脂肪酸(VFAs)产量、溶解性化学需氧量(SCOD)、溶解性蛋白质及多糖等指标,探究了不同剂量颗粒活性炭(GAC)与PS预处理对高固污泥产酸发酵的最佳条件。结果表明,当PS和GAC投加量分别为1.50 mmol·g−1(以总固体计)和0.65 g g−1(以总固体计)时,在发酵前期产酸速率相比于对照组提高了341.43%,后续发酵过程中,VFAs最大产量相比于对照组提高了28.43%。其中,乙酸作为优质碳源,其质量浓度增加了48.98%;继续增加GAC剂量时,反应器厌氧发酵性能下降,其原因可能是过量GAC会消耗已生成的SO4−·,降低污泥水解作用,同时GAC表面对VFAs的吸附也导致产酸量下降。三维荧光分析表明,在产酸量较高的反应器中,氨基酸、芳香族蛋白质等溶解性有机物的质量浓度较低,这说明适量椰壳颗粒活性炭活化PS预处理方式可提高高固厌氧发酵中微生物对于水解底物的利用率,从而提高污泥的厌氧产酸性能。本研究结果可为炭活化PS预处理技术在高固污泥厌氧消化中的应用提供参考。Abstract: To analyze the effect of coconut shell granular activated carbon activated sodium persulfate (PS) pretreatment on the performance of anaerobic fermentation and hydrolysis of high-solid sludge for acid production, the optimal conditions with different doses of granular activated carbon (GAC) and PS were explored by the yield of volatile fatty acids (VFAs), soluble chemical oxygen demand (SCOD), soluble protein and polysaccharide. When the dosage of PS and GAC were 1.50 mmol·g−1 (based on the total solids) and 0.65 g·g−1 (based on the total solids), respectively, the acid production rate in the early fermentation stage increased by 341.43%. With the progress of fermentation, the maximum production of VFAs increased by 28.43% and the acetic acid as the high-quality carbon source increased by 48.98% compared with the control group. Increasing the dosage of GAC would lead to the decline of anaerobic fermentation performance of the reactor, which might be due to the consumption of the generated SO4−· by excessive GAC in the pretreatment process, resulting in the reduction of hydrolysates, and the adsorption of VFAs on the surface of GAC leads to the decrease of acid production simultaneously. Three-dimensional fluorescence analysis showed that the concentrations of soluble substances, such as amino acids and aromatic proteins, were relatively low in the reactor with high acid production, indicating that appropriate amount of coconut shell granular carbon activated PS pretreatment could improve the utilization rate of hydrolyzed substrates, and improve the anaerobic digestion performance of sludge. The results can provide a theoretical reference for the application of carbon-activated PS pretreatment technology in anaerobic digestion of high-solid sludge.
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表 1 污泥主要性质
Table 1. Main characteristics of the sludge
供试污
泥品种TCOD/
(mg·L−1)SCOD/
(mg·L−1)含水率/
%TS/
%VS/
%pH 种泥 63 000±300 9 500±300 88.28 11.32 3.81 10 高固污泥 65 000±600 9 700±300 89.53 10.93 4.35 5.5 -
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