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随着我国碳达峰和碳中和目标的提出,传统工业行业的绿色低碳转型发展势在必行。浮选作为一种常用的选矿方法,耗水量巨大,优化浮选单元的取水结构,加大废水循环利用,不仅可以缓解常规用水的供求矛盾,节约浮选用水成本,还能在一定程度上促进绿色矿山的建设。城镇污水处理厂的二级出水具有水量大、受季节和气候影响小、就地可取的特点,是浮选单元的潜在供水水源。然而,二级出水中的细菌、病毒、原生动物等病原微生物在回用过程中会通过气溶胶传播、皮肤接触等途径对选矿厂工人造成潜在的健康风险[1-3]。有研究表明,城镇污水处理厂的出水回用于景观娱乐性用水时,休闲活动参与者的水源性肠道病原体暴露风险增加,有可能引发急性肠胃疾病、呼吸道疾病、皮肤疾病[4-5];用于喷洒灌溉、洗车、道路清扫时,水中病原体会以气溶胶的形式对人体,产生吸入暴露风险[6-8]。而将二级出水回用于干旱地区的矿区选矿厂浮选用水时,其中的病原微生物的削减和回用后对矿物分离的影响尚无报道。
近年来,臭氧氧化作为一种高效的氧化消毒技术受到了广泛关注[9-11],臭氧自身的氧化作用及其在水中分解产生的羟基自由基不仅可对病原体产生强大的灭活作用、削减病原微生物浓度[12-13]、降低回用水使用风险[14-15],而且可以降解水中有机物。刘洪均等[16]证明了城镇污水处理厂二级出水可以回用于内蒙古某铜钼矿浮选流程。随后,他们进一步发现回用水中的大肠杆菌及病毒等病原微生物在浮选过程存在潜在的健康风险,臭氧氧化作为应急处理措施可以应对该风险,但该研究并未确定臭氧氧化工艺的具体参数及优化后的浮选效果[17-19]。
基于此,本研究采用臭氧氧化技术深度处理城镇污水处理厂二级出水,优化了臭氧氧化操作参数,评价了病原微生物的去除效果,比较了二级出水臭氧处理前后浮选流程中各岗位的健康风险,系统评估了臭氧氧化二级出水回用于浮选单元的适用性。本研究成果可为城镇污水厂二级出水以及矿山生活区污水处理后回用于干旱地区矿区选矿厂提供参考。
臭氧氧化二级出水回用于选矿浮选的适用性
Feasibility of ozonation advanced treatment of secondary effluent for water reuse in flotation unit of mineral processing plants
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摘要: 为优化干旱矿区浮选单元的取水结构,降低市政污水处理厂二级出水的回用风险,以内蒙古某铜钼矿为代表性研究对象,采用臭氧氧化工艺对该区域市政污水处理厂二级出水进行深度处理,探讨其对水中病原微生物的去除效果,研究处理后的二级出水对浮选指标的影响以及相应的健康风险,评估氧化处理工艺的二级出水回用于选矿浮选单元的适用性。结果表明,二级出水中大肠杆菌浓度具有明显的季节分布性,最高浓度可达3.85 ×106 个·mL−1,轮状病毒检出率为77.78%,直接回用具有一定风险;而且浮选用水的水质对浮选指标影响较大,随着COD、悬浮物浓度的下降,精矿中铜、钼的品位和回收率相应增加,浮选指标得到改善;采用臭氧氧化处理工艺二级出水,在臭氧投加量为6 mg·L−1、氧化时间为10 min、不调节pH的情况下,二级出水中粪大肠杆菌衰减率可达3.44lg 个·L−1。在该工艺条件下,使用处理后的二级出水进行浮选,浮选产品指标合格,且粪大肠杆菌单次暴露感染风险为4.71×10−8~1.35×10−6,年暴露感染风险为1.59×10−6~4.70×10−4,均为可接受水平。Abstract: In order to optimize the water supply structure of flotation unit in mineral processing plant of arid area and decrease the recycle risk of secondary effluent in wastewater treatment plant (WWTP), a copper-molybdenum mine located in Inner Mongolia was taken as the representative case, ozonation oxidation was employed to perform the advanced treatment of secondary effluent from a WWTP in this region. Then the removal efficiency of pathogenic microorganisms in secondary effluent was determined, the influence of treated secondary effluent on the flotation indices and the corresponding health risk were studied, the feasibility of these treated secondary effluent for water reuse in flotation unit of mineral processing plants was also evaluated. The results showed that the Fecal coliform concentration in secondary effluent had an obvious seasonal distribution characteristic with the highest concentration of 3.85×106mL−1, the detection rate of rotavirus was 77.78%, these indicated that direct reuse of secondary effluent had a potential risk. Moreover, the water quality for floatation had a significant effect the flotation indices. With the decrease of COD and suspended solids in water, the grade and recovery of copper and molybdenum in the concentrate increased, and the flotation indices were improved. When ozonation oxidation was used to treat secondary effluent, the attenuation rate of Fecal coliform could reach 3.44log·L−1 at ozone dosage of 6 mg·L−1, oxidation time of 10 min and non-adjusted pH. Under these conditions, the treated secondary effluent could meet the flotation water quality requirements and the qualified flotation products were achieved. Moreover, the single and the annual exposure risk of Fecal coliform were 4.71×10−8~1.35×10−6 and 1.59×10−6~4.70×10−4, respectively, which were both at an acceptable level.
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Key words:
- arid mining area /
- ozone oxidation /
- flotation /
- pathogen
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表 1 污水处理厂二级出水病原微生物检测结果
Table 1. Detection results of pathogens in secondary water of sewage treatment plant
月份 粪大肠杆菌/
(103个·L−1)沙门氏菌/
(103 CFU·L−1)金黄色葡萄球菌/
(103 CFU·L−1)粪链球菌
/(103 CFU·L−1)腺病毒 轮状
病毒柯萨奇
病毒3月 608 303 0 95 − − + 4月 1 680 320 0 1 360 − + − 5月 362 130 37 213 + + − 6月 1 320 160 0 203 + + + 7月 3 560 200 232 2 560 + + − 8月 3 850 150 102 2 850 + + + 9月 370 110 0 106 + + − 10月 950 260 0 1 800 − + + 11月 680 280 0 950 − − − 注:“+”为阳性,“−”为阴性。 表 2 浮选用水和矿物颗粒中粪大肠杆菌暴露感染概率
Table 2. Probability of Fecal escherichia coli exposure in flotation water and mineral particles
暴露途径 岗位 单次暴露风险 年暴露风险 4 mg·L−1臭氧 6 mg·L−1臭氧 4 mg·L−1臭氧 6 mg·L−1臭氧 浮选用水 SP1 8.09×10−5 1.35×10−6 1.62×10−3 4.70×10−4 矿物颗粒 SP2 2.24×10−6 4.00×10−7 4.47×10−5 7.99×10−6 SP3 1.42×10−6 1.60×10−7 2.84×10−5 3.21×10−6 SP4 4.08×10−7 1.23×10−7 8.15×10−6 2.42×10−6 SP5 4.79×10−7 7.99×10−8 9.59×10−6 1.59×10−6 SP6 4.00×10−7 1.79×10−7 7.99×10−6 3.52×10−6 SP7 4.79×10−7 8.79×10−8 9.60×10−6 1.76×10−6 SP8 2.40×10−7 9.59×10−8 4.79×10−6 1.92×10−6 SP9 1.60×10−7 4.79×10−8 3.20×10−6 7.99×10−6 SP10 4.02×10−7 6.39×10−8 7.89×10−6 1.8×10−6 表 3 再生水铜钼混合浮选闭路实验结果
Table 3. Results of copper-Molybdenum mixed flotation using reclaimed water
水质种类 品位/% 回收率/% 铜 钼 铜 钼 混合水 16.54 0.64 68.77 46.87 臭氧氧化后的混合水 19.35 1.05 81.54 75.36 二级出水 20.99 1.14 82.54 76.33 臭氧氧化后的二级出水 24.86 1.68 86.28 79.55 自来水 25.91 1.80 90.60 88.40 表 4 浮选用水水质
Table 4. water quality in flotation process
水质种类 COD/(mg·L−1) 悬浮物/(mg·L−1) 浊度/(NTU) 氨氮/(mg·L−1) 总磷/(mg·L−1) pH 混合水 170.87 155.67 20.55 67.42 6.65 7.8 臭氧氧化后的混合水 71.42 50.78 5.34 15.44 2.30 7.2 二级出水 65.50 56.34 3.42 5.65 1.60 7.5 臭氧氧化后的二级出水 22.70 50.55 1.85 1.81 1.35 7.6 自来水 2.34 5.62 1.65 0.52 0.10 7.2 -
[1] WÉRY N, LHOUTELLIER C, DUCRAY F, et al. Behaviour of pathogenic and indicator bacteria during urban wastewater treatment and sludge composting, as revealed by quantitative PCR[J]. Water Research, 2008, 42(1-2): 53-57. [2] 张振兴, 王江权, 郑祥. 水体病原微生物定量风险评价: 历史、现状与发展趋势[J]. 环境科学学报, 2016, 36(1): 1-6. [3] ESFAHANI A R, BATELAAN O, HUTSON J L. Combined physical, chemical and biological clogging of managed aquifer recharge and the effect of biofilm on virus transport behavior: A column study[J]. Journal of Water Process Engineering, 2019, 33 (10): 1-11. [4] BEAUDEQUIN D, HARDEN F, ROIKO A , et al Modelling microbial health risk of wastewater reuse: Asystems perspective [J]. Environment International , 2015, 84 (8) : 131-141 [5] 孙傅, 沙婧, 张一帆, 等. 城市景观娱乐水体微生物风险评价[J]. 环境科学, 2013, 34(3): 934-942 [6] KISTEMANNA T, SCHMIDT A A , FLEMMING H C. Post-industrial river water quality: Fit for bathing again? [J]. International Journal of Hygiene and Environmental Health, 2016, 219 (7) : 629-642. [7] ABIA, A L K, EUNICE U J, GENTH B, et al. Quantitative microbial risk assessment (QMRA) shows increased publichealth risk associated with exposure to river water under conditions ofriverbed sediment resuspension[J]. Science of the Total Environment, 2016, 566/567(5): 1143-1151. [8] 吴乾元, 李永艳, 胡洪营, 等. 再生水在洗车利用中的暴露剂量研究[J]. 环境科学学报, 2013, 33(3): 845-850. [9] 王连杰, 李金河, 郑兴灿等. 城镇污水系统中病毒特性和规律相关研究分析[J]. 中国给水排水, 2020, 36(6): 14-21. [10] 董慧峪, 李凌菲, 刘沛峰, 等. 饮用水消毒工艺对病毒的灭活[J]. 环境工程学报, 2020, 14(7): 1718-1727. doi: 10.12030/j.cjee.202002138 [11] 张松, 李菲菲, 史晨, 等. 生活污水的臭氧深度处理及其急性毒性[J]. 环境工程学报2017, 11(6): 3469-3474. [12] 潘观连, 张逢, 席劲瑛, 等. 臭氧对再生水中指示病原微生物的灭活特性[J]. 环境工程学报2015, 9(7): 3192-3196. [13] MELNIK L O, VAKULENKO V F, SAPRYKINA M M, et al. Change of the oxidation-reduction potential of model and natural waters in the ozone disinfection process[J]. Journal of Water Chemistry and Technology, 2021, 43(1): 85-91. [14] TORII S, MIURA F, ITAMOCHI M, et al. Impact of the heterogeneity in free chlorine, UV254, and ozone susceptibilities among coxsackievirus B5 on the prediction of the overall inactivation efficiency[J]. Environmental Science and Technology, 2021, 55(5) : 3156-3164 [15] ZHAO J, SHANG C, ZHANG X, et al. The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine[J]. Water Research, 2021, 190(11): 116680. [16] 刘洪均, 徐涛, 孙春宝. 城市中水用于乌努格吐山铜钼矿浮选过程的研究[J]. 有色金属:选矿部分, 2014(1): 56-60. [17] 窦培谦, 寇珏, 孙春宝, 等. 城市再生水中大肠杆菌在浮选过程中迁移规律[J]. 工程科学学报, 2017, 39(5): 669-675. [18] 窦培谦, 寇珏, 孙春宝, 等. 城市再生水中病毒对浮选过程的影响规律[J]. 中国矿业, 2017, 26(8): 133-139. [19] 窦培谦, 孙春宝. 城市再生水回用于浮选的健康风险评价及应急处置[J]. 安全与环境学报, 2018, 18(1): 252-256. [20] 中华人民共和国国家卫生和计划生育委员会. 食品微生物学检验 粪大肠菌群计数: GB 4789.39-2013 S].
[21] 程丽娟, 薛泉宏. 微生物学实验技术[M]. 北京: 科学出版社, 2012. [22] ABIA L K A, UBOMBA-JASWA E, SSEMAKALU C C, et al. Development of a rapid approach for the enumeration of Escherichia coli in riverbed sediment: Case study, the Apies River, South Africa[J]. Journal of Soils and Sediments, 2015, 15(12): 2425-2432. [23] FEWTRELL L, BARTRAM J. Water Quality: Guidelines, Standards and Health-Assessment of Risk and RiskManagement for Water-Related Infectious Disease World Health Organization (WHO) Water Series[M]. London, IWA Publishing, 2001. [24] USEPA & USDA/FSIS. Microbial risk assessment guideline: Pathogenic microorganisms with focus on food andwater[EB/OL]. (2012-07)[2022-04].https://www.epa.gov/risk/microbial-risk-assessment-guideline-pathogenic-microorganisms-focus-food-and-water. [25] 郑晓英, 王俭龙, 李鑫玮等. 臭氧氧化深度处理二级处理出水的研究[J]. 中国环境科学, 2014, 34(5): 1159-1165. [26] 窦培谦. 再生水中病原微生物在铜钼矿浮选过程中的迁移特征研究[D]. 北京: 北京科技大学, 2019.