Sjon Kortekaas , Gladys Vidal , He Yan-Ling , Gatze Lettinga , Jim A. Field
{"title":"Anaerobic-aerobic treatment of toxic pulping black liquor with upfront effluent recirculation","authors":"Sjon Kortekaas , Gladys Vidal , He Yan-Ling , Gatze Lettinga , Jim A. Field","doi":"10.1016/S0922-338X(98)80041-X","DOIUrl":null,"url":null,"abstract":"<div><p>Alkaline pulping liquors are problematic for anaerobic treatment due to their toxicity to methanogens and their relatively large fraction of inert lignin. In previous research, toxicity due to wood extractives was shown to be highly eliminated during aerobic wastewater treatment, but not during anaerobic treatment. These observations have led to the proposal of a detoxification strategy denominated upfront dilution, based on the sequenced anaerobic-aerobic treatment of the pulping liquor, recirculating the aerobic effluent to dilute the incoming influent to sub-toxic concentrations. In this study, the treatment of highly toxic hemp stem wood black liquor (HSWBL) in lab-scale UASB reactors with upfront dilution was compared with direct anaerobic treatment and with direct aerobic treatment. Direct anaerobic treatment of 12 g COD/<em>l</em> HSWBL led to almost complete inhibition of the methanogenic activity within 14 d. However, recirculation of 75% of the aerobic post-treatment effluent for upfront dilution of the toxic HSWBL, enabled anaerobic treatment at loading rates up to 21.5 g COD/<em>l</em><sub>UASB</sub>·d without significant inhibition of the methanogenic activity. Extensive detoxification was confirmed during anaerobic-aerobic treatment of 20 g COD/<em>l</em> HSWBL recirculating 86% of the aerobic effluent. COD and BOD removal was 72% and 97%, respectively, after anaerobic-aerobic treatment at an overall loading rate of 3.6 g COD/<em>l</em>·d, while 30–35% of the incoming COD was recovered as methane. Batch-assays demonstrated significant detoxification after anaerobic-aerobic treatment of HSWBL. Treatment efficiencies and detoxification during anaerobic-aerobic and aerobic treatment were similar. However, the anaerobic-aerobic treatment system provided 50% lower surplus sludge production, production of 0.16 m<sup>3</sup> methane/kg COD<sub>removed</sub> as an energy source, less nutrient dosage and substantial reductions in aeration costs. During anaerobic-aerobic treatment as well as aerobic treatment significant lignin removal was obtained, ranging from 28–58%. Lignin removal could be attributed to biodegradation of low molecular weight lignin (MW < 2.2 kD). The lignin which survived biological treatment was extensively polymerized to MW of > 34 kD.</p></div>","PeriodicalId":15696,"journal":{"name":"Journal of Fermentation and Bioengineering","volume":"86 1","pages":"Pages 97-110"},"PeriodicalIF":0.0000,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0922-338X(98)80041-X","citationCount":"55","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Fermentation and Bioengineering","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0922338X9880041X","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 55
Abstract
Alkaline pulping liquors are problematic for anaerobic treatment due to their toxicity to methanogens and their relatively large fraction of inert lignin. In previous research, toxicity due to wood extractives was shown to be highly eliminated during aerobic wastewater treatment, but not during anaerobic treatment. These observations have led to the proposal of a detoxification strategy denominated upfront dilution, based on the sequenced anaerobic-aerobic treatment of the pulping liquor, recirculating the aerobic effluent to dilute the incoming influent to sub-toxic concentrations. In this study, the treatment of highly toxic hemp stem wood black liquor (HSWBL) in lab-scale UASB reactors with upfront dilution was compared with direct anaerobic treatment and with direct aerobic treatment. Direct anaerobic treatment of 12 g COD/l HSWBL led to almost complete inhibition of the methanogenic activity within 14 d. However, recirculation of 75% of the aerobic post-treatment effluent for upfront dilution of the toxic HSWBL, enabled anaerobic treatment at loading rates up to 21.5 g COD/lUASB·d without significant inhibition of the methanogenic activity. Extensive detoxification was confirmed during anaerobic-aerobic treatment of 20 g COD/l HSWBL recirculating 86% of the aerobic effluent. COD and BOD removal was 72% and 97%, respectively, after anaerobic-aerobic treatment at an overall loading rate of 3.6 g COD/l·d, while 30–35% of the incoming COD was recovered as methane. Batch-assays demonstrated significant detoxification after anaerobic-aerobic treatment of HSWBL. Treatment efficiencies and detoxification during anaerobic-aerobic and aerobic treatment were similar. However, the anaerobic-aerobic treatment system provided 50% lower surplus sludge production, production of 0.16 m3 methane/kg CODremoved as an energy source, less nutrient dosage and substantial reductions in aeration costs. During anaerobic-aerobic treatment as well as aerobic treatment significant lignin removal was obtained, ranging from 28–58%. Lignin removal could be attributed to biodegradation of low molecular weight lignin (MW < 2.2 kD). The lignin which survived biological treatment was extensively polymerized to MW of > 34 kD.
碱性制浆液由于对产甲烷菌的毒性和相对较大比例的惰性木质素而成为厌氧处理的问题。在以前的研究中,由于木材提取物的毒性被证明在好氧废水处理中被高度消除,但在厌氧处理中却没有。这些观察结果导致提出了一种名为“预先稀释”的解毒策略,该策略基于对纸浆液的顺序厌氧-好氧处理,再循环好氧废水以将进入的进水稀释到亚毒性浓度。在本研究中,在实验室规模的UASB反应器中,采用预先稀释的方法处理高毒大麻茎木黑液(HSWBL),并与直接厌氧处理和直接好氧处理进行了比较。直接厌氧处理12 g COD/l HSWBL可在14 d内几乎完全抑制产甲烷活性。然而,将75%的好氧处理后出水再循环用于预先稀释有毒的HSWBL,使厌氧处理的负荷率达到21.5 g COD/lUASB·d,而没有显著抑制产甲烷活性。以20 g COD/l HSWBL循环86%的好氧出水进行厌氧-好氧处理,证实了广泛的解毒作用。以3.6 g COD/l·d的总负荷速率进行厌氧-好氧处理后,COD去除率为72%,BOD去除率为97%,其中30-35%的COD被回收为甲烷。批量试验表明,在厌氧-好氧处理后,HSWBL具有显著的解毒作用。厌氧-好氧处理和好氧处理的处理效率和解毒效果相似。然而,厌氧-好氧处理系统可使剩余污泥产生量降低50%,产生0.16 m3甲烷/kg codre污泥作为能源,减少营养物用量,并大幅降低曝气成本。在厌氧-好氧处理和好氧处理中,木质素的去除率在28-58%之间。木质素脱除可归因于低分子量木质素(MW <2.2 kD)。经生物处理后的木质素被广泛聚合成MW的>34 kD。