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随着我国食品行业的发展,食品生产过程中产生的废水排放量也与日俱增. 在2018年的时候,不同行业的废水排放总量是2045794万t,其中食品加工行业的废水排放量占据比例是8.46%,在排放量上位列第6位[1]. 食品加工行业废水普遍具有含盐、高有机质、高油等共同特征,污染物总体浓度较大. 曾有报道指出食品加工行业的废水含
${\rm{SO}}_4^{2-} $ 浓度高达1.5%以上[2],其中所含的有机物含量也较高,COD范围在5000—13000 mg·L−1波动[3]. 目前,国内外对于高盐有机废水处理普遍的观点是:先对废水中的有机物进行有效去除,减少废水中的有机质,然后再对盐分进行回收,最终实现高盐有机废水的资源化利用[4-5].目前对高盐废水中高浓度有机物的去除办法主要有厌氧和好氧生物处理. 由于废水中含有高浓度的硫酸盐,在厌氧条件下会产生H2S或S2−等有毒有害物质对厌氧微生物有毒害作用[6— 7],故厌氧生物技术不适合处理高硫酸盐有机废水. 而传统的好氧工艺存在污泥浓度不高、微生物流失、处理负荷低的问题,不易于驯化耐盐嗜盐微生物. 好氧膜生物反应器(aerobic membrane bioreactor,MBR)技术相较于传统好氧工艺,可以很好的将污泥截留在系统中,提高系统微生物量,有效降解高盐废水中的有机物. 此外,在MBR中能将污泥停留时间(sludge retention time, SRT)和水力停留时间(hydraulic retention time, HRT)分开控制,更好的运行管理,近几年在高盐废水处理行业中受到普遍关注[8]. 目前MBR技术应用于高盐废水中有一定研究,如刘传伟[9]在利用MBR工艺处理含不同比例高盐废水时,生物系统去除有机物的耐盐浓度在17 g·L−1;当系统中盐度在22.75 g·L−1时,系统处理效果严重恶化,去除率下降到75%. 张哲等[10]采用MBR工艺处理含50%海水的污水,通过合理调整运行参数,如控制COD为700—800 mg·L−1,氨氮为80—100 mg·L−1,HRT为12 h,反应器内污泥浓度为7—8 g·L−1及好氧区DO为1—2 mg·L−1,取得了较好的污染物去除效果,COD和氨氮的平均去除率分别达到91.91%和91.44%. Hong等[11]对比研究了MBR和传统活性污泥法处理高盐水产养殖废水的有机物去除效率,发现当含盐量增加35 g·L−1时,MBR系统的COD去除率仍保持在96%以上,而传统活性污泥法却随着含盐量升高去除率不断下降,当升高至30 g·L−1时,去除率就已降至68%. 这说明在处理高盐废水时采用MBR工艺较传统活性污泥法具有更好的有机物去除效率,且能适应更高的盐度.
目前高盐废水的生物处理的研究发现,由于高浓度无机盐对微生物的毒害和抑制作用,高盐废水在生物处理过程中普遍存在处理负荷不高,去除效率不稳定等问题[9,11]. 为了探究MBR系统能否在高盐环境下建立稳定高效的去除污染物体系,本研究针对连云港某营养食品加工企业生产的两种SO42-浓度分别为1.6%和2.6%的废水,采用两套中试规模好氧膜生物反应器(MBR)进行处理. 通过对出水的COD、氨氮、TN以及TP等定期监测,研究不同SO42-浓度下两套装置的盐度驯化以及负荷提升时期的污染物降解规律,以期为MBR处理高盐高浓度有机废水提供理论基础和应用指导.
MBR处理不同浓度高硫酸盐有机废水效能比较
Performance comparison of MBRs in treating organic wastewater with different concentrations of sulfate
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摘要: 针对食品加工过程中产生的高
${\rm{SO}}_4^{2-} $ 有机物废水,采用MBR工艺对其进行处理研究,分别考察了1.6%和2.6%${\rm{SO}}_4^{2-} $ 浓度下反应器容积负荷和污染物去除情况. 经过110天的运行时间发现,进水${\rm{SO}}_4^{2-} $ 浓度为1.6%的系统能获得更高的容积负荷和污染物去除效率,其最大容积负荷为1.0 kg·(m3·d)−1 COD, COD去除率为97.7%;而另一方面较高的无机盐环境进水${\rm{SO}}_4^{2-} $ 浓度为2.6%${\rm{SO}}_4^{2-} $ 系统下,获得的最大容积负荷仅为0.5 kg·(m3·d)−1 (按COD算),COD去除率为96.4%. 在2.6%${\rm{SO}}_4^{2-} $ 浓度下,微生物受到的抑制更强,有机物降解效果低于1.6%${\rm{SO}}_4^{2-} $ 的系统. 此外,氨氮的去除效果也受盐度的影响,1.6%${\rm{SO}}_4^{2-} $ 系统的氨氮去除率可达91%以上,而2.6%${\rm{SO}}_4^{2-} $ 系统的氨氮去除率在82%左右. 通过长时间的运行,两套MBR装置均建立了同步硝化反硝化的脱氮体系,对总氮具有一定的去除效率. 其中1.6%${\rm{SO}}_4^{2-} $ 系统中总氮的去除率为89.5%,而2.6%${\rm{SO}}_4^{2-} $ 系统中总氮的去除效率为80.7%. 两套反应器装置对总磷均能达到100%的去除效果. 综上,不同盐度对MBR体系容积负荷和有机物去除率具有显著影响. 相比于2.6%${\rm{SO}}_4^{2-} $ ,1.6%${\rm{SO}}_4^{2-} $ 浓度条件下能获得更高的容积负荷和更好的污染物去除效果. 本研究可为MBR应用于高盐高浓度有机物废水的处理提供理论基础和实践指导.Abstract: The membrane bioreactor (MBR) was used to treat the organic wastewater with high${\rm{SO}}_4^{2-} $ produced in the food processing process, and the reactor volume load rate (VLR) and organic pollutant removal efficiency were compared with different${\rm{SO}}_4^{2-} $ concentration at 1.6% and 2.6% respectively. the reactors operated for 110 d, and it was found that the reactor with influent of 1.6%${\rm{SO}}_4^{2-} $ could obtain higher VLR of 1.0 kg· (m3· d)−1 COD and better COD removal efficiency of 97.7%. However, for the influent of 2.6%${\rm{SO}}_4^{2-} $ , the maximum VLR and COD removal efficiency were only 0.5 kg· (m3· d)−1 COD and 96.4% respectively. With the concentration of 2.6%${\rm{SO}}_4^{2-} $ , the inhibition effect of the salinity on the microorganisms was stronger than that of 1.6%${\rm{SO}}_4^{2-} $ , thus the degradation efficiency of organic matter was lower at 2.6%${\rm{SO}}_4^{2-} $ . In addition, the removal efficiency of ammonia nitrogen was also affected by salinity, which was verified by the fact that ammonia nitrogen removal efficiencies were 91% and 82% at concentrations of 1.6%${\rm{SO}}_4^{2-} $ and 2.6%${\rm{SO}}_4^{2-} $ respectively. After a long-term operation period, two sets of MBR units had established simultaneous nitrification and denitrification systems. The removal efficiency of total nitrogen was 89.5% in 1.6%${\rm{SO}}_4^{2-} $ system, while that was 80.7% in 2.6%${\rm{SO}}_4^{2-} $ system. Moreover, 100% removal efficiencies for total phosphorus in two reactors were obtained. In conclusion, different salinity presented significant influence on the VLR and organic matter removal in the MBR system. Compared with the reactor of 2.6%${\rm{SO}}_4^{2-} $ , the reactor of 1.6%${\rm{SO}}_4^{2-} $ could obtain higher VLR and better pollutant removal efficiency. This study can provide theoretical basis and practical guidance for the application of MBR in the treatment of high-salt and high-concentration organic wastewater. -
表 1 不同
系统进水水质${\rm{SO}}_4^{2-} $ Table 1. The influent quality of
system${\rm{SO}}_4^{2-} $ 第1 天—第25 天
Day 1 — Day 25第26 天—第60 天
Day 26 — Day 60第61 天—第110 天
Day 61 — Day 1101.6% 系统${\rm{SO}}_4^{2-} $ pH 3.8—4.2 3.8—4.2 3.8—4.2 硫酸根/% 1.6—1.7 1.7—1.8 1.7—1.8 COD/(mg·L−1) 5400—5600 5400—5600 7500—8100 TDS/(g·L−1) 27—30 27—30 27—30 电导率/(ms·cm−1) 25—30 28—30 28—30 TN/(mg·L−1) 20—25 180—200 320—350 TP/(mg·L−1) 5—10 8—10 8—10 氨氮/(mg·L−1) 15—20 15—20 15—20 Ca/(mg·L−1) 25—35 25—35 25—35 Mg/(mg·L−1) 5—15 5—15 5—15 Fe/(mg·L−1) 0.1—0.6 0.1—0.6 0.1—0.6 pH 3.7—3.9 3.5—4.1 3.6—4.2 2.6% ${\rm{SO}}_4^{2-} $ 硫酸根/(mg·L−1) 2.6—2.8 2.6—2.8 2.2—2.3 COD/(mg·L−1) 8000—8900 7000—7800 7500—8000 TDS/(g·L−1) 42—45 45—55 50—54 电导率/(ms·cm−1) 38—40 38—40 38—40 TN/(mg·L−1) 28—30 320—350 320—350 TP/(mg·L−1) 10—15 10—15 15—20 氨氮/(mg·L−1) 15—20 15—20 15—20 Ca/(mg·L−1) 35—45 35—45 35—45 Mg/(mg·L−1) 10—20 10—20 10—20 Fe/(mg·L−1) 0.2—0.8 0.2—0.8 0.2—0.8 表 2 MBR反应器运行策略
Table 2. Operating strategy of MBR reactor
浓度$ {\rm{SO}}_4^{2-} $ concentration$ {\rm{SO}}_4^{2-} $ 阶段
Stage天数/d
Days容积负荷/(kg·(m3·d)−1)
VLRHRT/d SRT/d 1.6% 提盐驯化阶 1—20 0.5 10 不排泥 负荷提升阶段Ⅰ 21—40 0.6 8.5 44 负荷提升阶段Ⅱ 41—80 0.72 8.5—10.2 44 负荷提升阶段Ⅲ 81—110 1.0 7 44 2.6% 提盐驯化阶段 1—36 0.5 16 不排泥 负荷稳定阶段 37—110 0.5 16—22 44 注:进水 浓度为1.6%的反应器在负荷提升阶段Ⅰ内(第26 天)开始排泥,控制SRT为44 d;1.6%系统在负荷提升阶段Ⅱ和2.6%系统的负荷稳定阶段进水COD有所变化,HRT作了相应调整.$ {\rm{SO}}_4^{2-} $
Note: The reactor with influent of 1.6% discharged sludge at the 26th day in stage I of VLR improvement, with SRT controlled at 44 days; As the influent COD concentration changed from stage Ⅱ of VLR improvement in 1.6% system and the VLR stabilizing stage in 2.6% system, the HRT was adjusted accordingly.$ {\rm{SO}}_4^{2-} $ -
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