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目前国内对渗滤液处理大多采用“预处理+生物处理+膜深度处理”的主流工艺. 其中,采用纳滤或反渗透滤等膜分离系统不可避免会产生占渗滤液处理总量约20%—30%的浓缩液[1]. 其中反渗透膜滤浓缩液中COD的浓度范围在500—1500 mg·L−1,其中腐殖质含量较高,占总TOC的27.4%—52.3%,总氮100—200 mg·L−1,其中有机氮含量较高,占总氮的50%—60%,同时浓缩液含盐量较高,电导率为7.53—20.05 ms·cm−1,处理难度极大,是众多垃圾填埋场面临的难题之一.
目前,对于浓缩液中有机物的处理已形成比较成熟的技术,如两级物料膜技术,臭氧高级氧化技术可以对有机物中腐殖质进行有效的分离和降解[2-3],而总氮的去除依然是处理的重点和难点. 对于总氮的去除,目前普遍采用的是生物处理技术,如A2/O技术[4],由于浓缩液可生化性差、有机氮含量高且盐度极高,导致传统脱氮微生物难以在极端环境下有效脱氮[5-7];耐盐微生物和嗜盐微生物在处理高含盐废水中发挥积极作用,通过耐盐菌或嗜盐菌接种强化活性污泥是处理含盐废水的最佳方法. 利用耐盐菌强化活性污泥处理硫酸钠质量分数为38%的精细化工行业产生的废水,其对COD的去除率大于95%[8];郭立[9]分离筛选出针对高含盐垃圾渗滤液中COD的降解菌种. 大多数的研究只关注COD的去除,对脱氮的关注较少,仅有的强化耐盐菌,也是传统的强化硝化菌和反硝化菌,由于渗滤液浓缩液水质差异较大,本研究处理的RO浓液有机氮含量较高,而对于强化有机氮氨化和好氧反硝化强化菌研究鲜有报道. 此外,目前对于高级氧化处理前后有机物变化研究较多,厌氧/好氧生物处理过程中有机物的去除效果研究较多,而对于处理过程中有机物成分的变化研究较少[8-10]. 因此,如何脱除渗滤液浓缩液中有机物和总氮,使渗滤液浓缩液达标排放仍是迫切需要解决的问题.
团队前期研究中开发了在高盐条件下仍具有良好的生长态势和污染物降解效果的厌氧耐盐菌TN-YN和好氧耐盐菌TP-HN,将耐盐菌与活性污泥法相结合耦合催化臭氧氧化,构建一种垃圾渗滤液反渗透膜滤浓缩液的处理方法. 在高盐条件下,通过厌氧耐盐菌的氨化作用先将浓缩液中有机氮转化为氨氮,再通过具有好氧反硝化功能的好氧耐盐菌强化好氧活性污泥,在好氧条件下实现NH4+-N、TN的同步去除[11],解决传统A2/O技术在高盐条件下反硝化受到抑制的问题,再通过催化臭氧氧化对难降解有机物的去除,确保出水中COD、TN达标排放. 同时,对比活性污泥、耐盐菌剂、活性污泥+耐盐菌剂3个体系的污染物去除效果、有机物去除效果和生物多样性变化,进一步探讨体系的脱氮机理,为揭示耐盐菌强化机理提供科学依据.
耐盐菌生物强化耦合催化臭氧氧化处理渗滤液RO浓液及微生物特性分析
Treatment of RO concentrate of leachate by salt-tolerant bacteria enhanced biotechnology coupled catalytic ozonation and analysis of microbial characteristics
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摘要: 针对传统生物工艺处理RO浓液耐盐性差、处理效率低等问题,本研究利用耐盐菌强化厌氧/好氧(A/O)活性污泥耦合催化臭氧氧化工艺以提升有机物和总氮的去除,对比活性污泥、耐盐菌剂、活性污泥+耐盐菌剂的3种体系对RO浓液中污染物去除效果、处理前后有机物成分变化以及微生物特性差异. 结果表明,较单独厌氧活性污泥和耐盐菌体系,厌氧强化体系有机氮的转化率分别提高了42%和37%;较单独好氧活性污泥和耐盐菌体系,好氧强化体系总氮去除率提升了37%和77%. 气质联用分析显示,原水有机物经生物和臭氧氧化处理后促使一些不饱和键断裂,提高了难降解有机物的降解. 处理后,水质指标可达《生活垃圾填埋场污染控制标准》表2标准. 高通量测序结果表明,Flavobacterium可能在厌氧强化体系高盐条件下的氨化过程中发挥关键作用;而Truepera、Paracoccus是好氧强化体系高盐条件下总氮高效去除的关键功能菌属. 功能基因预测结果显示,氨化基因npr是Flavobacterium菌属的关键基因,进一步证实测序结果推测;好氧强化体系中nap、nar、nir、nor反硝化基因的相对丰度均高于单独体系,揭示了强化体系总氮高效去除的机理.Abstract: Aiming at the problems of poor salt tolerance and low treatment efficiency of RO concentrated solution treated by traditional biological treatment process, this study used salt-tolerant bacteria to strengthen the anaerobic/aerobic (A/O) activated sludge coupled catalytic ozonation process to improve the removal of organic matter and total nitrogen. The removal efficiency of pollutants in RO concentrate, the change of organic matter composition before and after treatment, and the differences in microbial characteristics of the three systems of activated sludge, salt-tolerant bacteria and activated sludge/salt-tolerant bacteria were compared. The results showed that the conversion rate of organic nitrogen in anaerobic enhanced system was increased by 42% and 37%, respectively, compared with single anaerobic activated sludge and salt-tolerant bacteria system, and compared with the single aerobic activated sludge and salt - tolerant bacteria system, the total nitrogen removal rate of aerobic enhanced system increased by 37% and 77%. GC-MS analysis showed that some unsaturated bonds were broken after biological and ozone oxidation treatment of raw water organic matter, which improved the degradation of refractory organics. After treatment, the water quality index can reach the Table 2 standard of “Standard for Pollution Control of Domestic Waste Landfill”. High-throughput sequencing results showed that Flavobacterium may play a key role in the ammoniation process under high salt conditions in the anaerobic enhanced system; while Truepera and Paracoccus are the key functional bacteria for efficient removal of total nitrogen under high salinity conditions in aerobic enhanced system. The functional gene prediction results showed that the ammoniation gene npr was the key gene of Flavobacterium, which further confirmed the sequencing results. The relative abundances of nap, nar, nir and nor denitrification genes in the aerobic strengthening system were higher than those in the single system, revealing the mechanism of efficient removal of total nitrogen in the strengthening system.
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表 1 实验用水水质
Table 1. Water quality for experimental use
水质指标
Water quality indexes浓度
ConcentrationTOC/(mg·L−1) 330.1 COD/(mg·L−1) 341.2 NH4+-N/(mg·L−1) 15.4 TN/(mg·L−1) 140.5 NO3-N/(mg·L−1) 41.2 有机氮/(mg·L−1) 83.9 盐度/% 1.8—2.1 表 2 检测项目及方法
Table 2. Detection Items and Methods
指标
Index检测方法
Detection methods有机污染物
TOC气相色谱-质谱联用(GC-MS)
TOC分析仪COD 碘化钾碱性高锰酸钾法 NH4+-N 纳氏试剂比色法 TN 碱性过硫酸钾消解分光光度法 NO3−-N 紫外分光光度法 DO 哈希溶氧仪 温度 温度计 污泥浓度 重量法 盐度 盐度计 表 3 臭氧催化氧化结果与排放标准
Table 3. Ozone catalytic oxidation results and emission standards
COD NH4+-N TN 排放标准/(mg·L−1) 100 40 25 臭氧催化氧化进水/(mg·L−1) 259 1.4 9.4 臭氧催化氧化出水/(mg·L−1) 56 — 4.3 去除率/% 78.37 100 54.25 表 4 有机物GC-MS结果分析
Table 4. Analysis of organic GC-MS results
渗滤液RO浓液
RO concentrated
solution of leachate厌氧出水
Anaerobic effluent好氧出水
Aerobic effluent臭氧出水
Ozone effluent有机物成分
Organic
components占比/%
Proportion有机物成分
Organic
components占比/%
Proportion有机物成分
Organic
components占比/%
Proportion有机物成分
Organic
components占比/%
ProportionUndecane 11.75 Silane,
cyclohexyldimethoxymethyl-5.122 Benzene,
1,4-dichloro-0.74 Cyclopentanl,
2-chloro-, trans-25.12 Dodecane 13.37 Dodecane 13.04 Decane,
2,4,6-trimethyl-3.33 Benzene,
1,3-dichloro-5.46 Tridecane 17.07 Tridecane 15.37 Benzene,
1,2,3-trichloro2.33 Benzene,
1,3,5-trichloro-2.46 Silane,
diethyl(2-decyloxy)pentadecyloxy-21.66 Bis(2-ethylhexyl) phthalate 18.67 Tridecane 14.02 Decane,
2,4,6-trimethyl-7.44 Silane,
trimethyl[5-methyl-2-(1-methylethyl)phenoxy]-6.921 Silane,
diethylheptyloxyoctadecyloxy-10.84 7,9-Di-tertbutyl-1-oxaspiro [4,5]deca-6,9-dien-8-one 0.87 N-Ethoxyisobuten-3-imine N- 0.44 Trimethylene oxide 13.22 Tetradecane,
2,6,10-trimethyl -0.90 Acetophenone 5.87 1-Silacyclo-3-pentene1- 2.70 1-Decanol,
2-5,9-dimethyl -0.81 Acetic acid, dichloro- 10.58 Benzoic acid,
3,5dicyclohexyl-4-hydroxy-, methyl ester1.42 1,3-Dioxane-2-propanol,
2-methyl-1,3-2.27 Diisooctyl phthalate 0.18 表 5 多样性指数表
Table 5. Diversity index table
样本
SampleAce Chao Coverage Shannon Simpson A1 541.446505 548.245283 0.997489 3.81816 0.046318 A2 185.890359 193.25 0.998998 3.021566 0.094163 A3 474.989895 480.784314 0.997192 3.599504 0.068381 B1 370.688575 384.965517 0.998404 3.441829 0.086591 B2 556.407202 567.053571 0.997048 3.492143 0.086164 B3 512.315624 525.636364 0.998111 3.492753 0.090136 -
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