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作为我国农业的支柱产业之一[1],畜禽养殖业向集约化、规模化方向发展,但规模化养殖产生了大量粪尿等污染物,畜禽养殖污染防治日益得到重视[2]。据相关统计[3]表明,以生猪养殖为代表的畜禽养殖业排放的有机物和总氮已经成为我国农业面源污染之首。
生猪养殖废水具有高氨氮(110~1 650 mg·L−1)、高有机污染物(2 000~30 000 mg·L−1)、高总氮(220~2 055 mg·L−1)等污染特征[4],其主要有还田处理,自然处理和生物处理等方式,其中还田处理和自然处理模式由于占地面积较大、二次污染等原因,而较少被采用。生物处理模式中多采用厌氧-好氧联合处理模式[5],但其存在处理工艺流程较长、出水难以稳定达标、冬季运行效果差等问题[6-7]。另一方面,由于生猪养殖废水属于低C/N比废水(4~7),缺氧阶段缺乏足够碳源,从而影响微生物生长和反硝化脱氮效果[8]。为增强废水生物处理脱氮效率,需要外加碳源,导致其处理成本和能耗较高[9]。姜超等[10]和SUI等[11]通过建立关联氧化还原电位、pH控制点的SMBR工艺,通过优化好氧曝气时间实现了实时控制短程硝化过程,
${\rm{NH}}_4^ + $ -N平均出水浓度为11.6 mg·L−1,去除率为98.3%;耗氧有机污染物的平均出水浓度(以COD计)为358 mg·L−1,去除率为95.3%;TN平均出水浓度为81 mg·L−1,去除率为92.7%;亚氮累积率在85%以上,因此,实现了常温下短流程高效处理畜禽养殖废水。本文在实验室规模SMBR工艺研究的基础上,通过研发中试规模SMBR工艺处理生猪养殖废水,考察了在低温环境下该工艺对污染物的去除效果及关键功能菌群的演替特征,以期为高效处理规模化畜禽养殖废水提供技术支撑。
温度对序批式膜生物反应器生物脱氮影响及微生物机制解析
Effects of temperature on biological nitrogen removal in batch membrane bioreactor and the microbial community mechanism
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摘要: 针对生猪养殖废水处理过程中普遍存在的脱氮效果不佳,工艺流程较长等问题,采用中试规模序批式膜生物反应器(SMBR)处理生猪养殖废水,并与猪场现有废水处理A2/O工艺进行了比较。结果表明:SMBR在运行温度逐步降低的情况下,可以取得较好的污染物去除效果,氨氮平均出水浓度为10 mg·L−1,去除率达到98.6%;总氮平均出水浓度为31 mg·L−1,去除率达到96.5%;COD为332 mg·L−1,去除率达到96.5%。猪场现有A2/O工艺对氨氮、总氮和耗氧有机物的去除率分别为99%、88%和97%。高通量测序和OUT分类结果表明,SMBR中主要的AOB为Nitrosomonas,NOB主要为Nitrospira、Nitrobacter和Nitrolancea。AOB是SMBR主要的硝化细菌,NOB是A2/O工艺中主要的硝化细菌,并且反硝化细菌在SMBR中的菌群丰度高于A2/O工艺中的反硝化菌群丰度。综上所述,与A2/O工艺相比,SMBR具有短流程和脱氮效果较好等优势,这可使其具有较好的应用前景。Abstract: Aiming at solving poor nitrogen removal performance and long process flow of swine wastewater treatment, a pilot scale sequencing batch membrane biological reactor(SMBR) was used to treat the swine wastewater in comparison with the current used A2/O treatment process. The results showed that good pollutant removals occurred even when the operating temperature of the SMBR decreased. The average effluent concentrations of ammonia, total nitrogen and COD were 10, 31 and 332 mg·L−1, and their removal rates were 98.6%, 96.5% and 96.5%, respectively; while their corresponding removal rates by A2/O were 99%, 88% and 97%, respectively. High-throughput sequencing and OTU classification showed that the major Ammonia-oxidizing bacteria (AOB) in the SMBR were Nitrosomonas, and the nitrite-oxidizing bacteria (NOB) were mainly Nitrospira, Nitrobacter and Nitrolancea. And AOB was the main nitrifying bacteria in the SMBR, NOB was the main nitrifying bacteria in the A2/O process, and the abundance of denitrifying bacteria in the SMBR was higher than that in the A2/O process. Thus, compared with the A2/O, SMBR had the advantages of the short process and better biological nitrogen removal efficiency, which makes it have more application prospect.
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表 1 SMBR和A2/O运行基本参数
Table 1. Basic parameters of SMBR and A2/O
工艺 阶段或池型 处理量/(m3·d−1) SRT/d HRT/d ${\rm{NH}}_4^ + $ -N负荷/
(kg·(m3·d)−1)有机物负荷/
(kg·(m3·d)−1)MLSS/(mg·L−1) 水温/℃ SMBR Ⅰ 10 15~20 5.6~6.6 0.11~0.14 1.48~1.75 7 200 20±2 Ⅱ 10 15~20 5.6~6.6 0.11~0.14 1.48~1.75 6 860 15±2 Ⅲ 10 15~20 5.6~6.6 0.11~0.14 1.48~1.75 8 240 10±2 A2/O 厌氧池 150 — 10 0.21 1.12~3.78 1 480 20±3 缺氧池 150 — 10 0.07 1.19~2.20 6 700 20±3 好氧池 150 — 10 0.01~0.02 0.35~0.8 4 340 20±3 表 2 生猪养殖废水水质
Table 2. Water quality parameters of swine wastewater
阶段 水温/℃ COD/(mg·L−1) ${\rm{NH}}_4^ + $ -N/(mg·L−1)${\rm{NO}}_3^ - $ -N/(mg·L−1)TN/(mg·L−1) 阶段Ⅰ 20±2 9 816±2 190 733.44±78.90 16.96±11.68 880.31±112.24 阶段Ⅱ 15±2 9 520±938 766.50±66.63 36.10±9.47 882.36±69.02 阶段Ⅲ 10±2 8 532±2 668 724.00±72.99 43.31±7.16 904.30±206.32 表 3 A2/O工艺处理生猪养殖废水效果
Table 3. Performance of A2/O process on swine wastewater treatment
mg·L−1 工况 氨氮 亚氮 硝态氮 总氮 COD 进水 745±79 0 37±9 844.5±5 5 850±56 厌氧池 835±1 0 23±3 909±50 2 245±91 缺氧池 65±9 0 20±3 96±31 274±21 好氧池 5±0.2 0 98±18 108±1 215±13 出水 7±2 0 94±25 107±7 216±10 去除率/% 99±0.2 — — 87.2±0.9 96.3±0.3 -
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