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近年来,生活垃圾焚烧处理得到了大力推广和发展,同时也引发了对处理过程中伴随的二次污染及其控制的关注,其中不乏关于垃圾渗滤液处理方式的研究。为得到较好的出水水质,常采用膜技术作为垃圾渗滤液处理流程的末端控制技术,但在该过程中产生的膜浓缩液,含有大量盐分和重金属,可生化性很低,是一种极难处理的高浓度废水[1-2]。
目前,国内外关于渗滤液膜浓缩液(简称浓缩液)的处理方法主要有回喷焚烧炉法[3]、回灌填埋场法[4-5]、蒸发法[6-8]、高级氧化法[9-14]等。蒸发处理技术具有占地面积小、产水能力高、可析出盐类晶体的优势,但设备腐蚀和能耗问题导致实际应用中经济效益较差。此外,高级氧化法也存在投资和运行费用较高的问题。回喷法最早在国外得以成功应用,其具有无害化彻底、工艺简单的特点。由于一些发达国家垃圾热值高,渗滤液产量少,可以直接将其回喷焚烧炉处理,但国内垃圾普遍具有热值较低、含水量高的特征,使得回喷法存在一定局限性。根据《关于进一步加强生物质发电项目环境影响评价管理工作的通知》(环发[2008]82号),垃圾焚烧厂产生的渗滤液应优先考虑回喷,浓缩液应焚烧处理。国内的焚烧厂渗滤液产生量约占垃圾总量的15%~30%,通常采用纳滤或反渗透进行深度处理。该过程产生的膜浓缩液约为渗滤液总量的15%~30%,水量较大,仍不宜直接回喷,需要再次减量处理[15]。近年来,一种以物料膜对膜浓缩液进行再浓缩的减量化技术逐渐在国内焚烧厂中使用,能够将回喷量控制在3.5%以下,而理论上回喷比控制在3.96%以内一般不会对焚烧工况造成影响[16]。因此,对于生活垃圾焚烧发电厂而言,浓缩液减量后雾化回喷到炉内焚烧是一种污染物去除效率最高且有效的处理方式。
在焚烧厂实际工程的运行操作中,浓缩液回喷对于焚烧系统以及烟气、飞灰的二次污染控制均存在潜在风险。目前,国内外文献中涉及浓缩液回喷后物质转化规律及回喷影响的研究较为缺乏,且由于条件限制,难以在焚烧厂实际运行中,对浓缩液回喷后污染物的迁移情况进行研究。因此,本研究通过实验模拟不同的回喷温度,研究了浓缩液回喷所得固相物质的特性和转化规律以及Cl、S等产生腐蚀性气体和物质的主要元素的变化规律,以此分析固相颗粒物对烟气系统负荷的影响及固相物质中腐蚀性成分对焚烧设备的影响,同时为回喷可行性的研究提供参考。
上海市某垃圾焚烧厂渗滤液膜浓缩液回喷焚烧后的固相物质转化特性
Transformation properties of solid matters produced by membrane concentrate spraying into incinerators in a waste incineration power plant of Shanghai city
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摘要: 为探究生活垃圾焚烧发电厂渗滤液膜浓缩液回喷炉膛对焚烧系统的影响,以上海市某垃圾焚烧厂的膜浓缩液为对象,利用马弗炉模拟回喷过程的不同温度条件,通过对烧干后固相物质的粒度测定和成分分析,研究其理化特性及物质转化规律,并分析Cl、S等产生腐蚀性气体的主要元素的变化规律。结果表明:850 ℃烧干浓缩液后形成的固体颗粒粒径主要集中在30~365 μm,质量分数达74.53%,粒径小于30 μm和大于365 μm的颗粒分别占24.89%和0.58%。浓缩液烧干后的固体几乎都是盐分,它们的结晶相以氯盐、钙盐(CaCl2、MgCl2、CaSO4)为主,且随着焚烧温度的升高,CaSO4的结晶度明显增高。浓缩液烧干后的固相物质中以O、Na、S、Cl、Mg、Ca、K等元素居多,元素含量变化趋势的转折点主要发生在900 ℃。研究表明,烟气系统的负荷设计上应充分考虑浓缩液回喷所带来的增量,设备维护上应注重对Cl腐蚀的防护,最佳的回喷温度应控制在900 ℃左右。Abstract: In order to explore the impact of the membrane concentrated leachate spraying into the incinerators on the incineration system in municipal solid waste (MSW) incineration power plants, the experiments was conducted with a muffle furnace to simulate different temperatures during spraying process of membrane concentrated leachate in a MSW incineration power plant in Shanghai. The size distribution, microstructure, composition and content of dried solid matters were characterized by particle size, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis. The results showed that the particle size of solid matters produced at 850 ℃ were distributed in 30~365 μm, and their mass percentage reached 74.53%, the particles with size less than 30 μm and high than 365 μm accounted for 24.89% and 0.58%, respectively. The solid matters after drying out of concentrated leachate were almost salt, and their crystal phase mainly consisted of CaCl2, MgCl2, CaSO4, and the crystallinity of CaSO4 increased obviously with the increase of temperature. O, Na, Mg, Cl, Ca, K were the main elements in the solid matters, and a turning point in element variational trends occurred at 900 ℃. The study indicated that loading increment by concentrate spraying should be given full consideration in designing the gas system, the equipment maintenance should pay attention to chlorine corrosion, and the optimum spray temperature could be controlled at about 900 ℃.
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Key words:
- membrane concentrate /
- incinerate /
- corrosion /
- solid matters
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表 1 浓缩液水样水质指标
Table 1. Water quality index of concentrate
pH COD /(mg·L−1) BOD /(mg·L−1) B/C NH4+-N /(mg·L−1) TN /(mg·L−1) VFA /(mg·L−1) K /(mg·L−1) 7.7±0.1 28 000±2 500 950±300 0.04±0.02 3.5±1.0 500±80 130±30 1 000±200 Na /(mg·L−1) Ca /(mg·L−1) Mg /(mg·L−1) Fe /(mg·L−1) Zn /(mg·L−1) Cl− /(mg·L−1) SO42− /(mg·L−1) HCO3−/(mg·L−1) 500±80 1 811±301 3 000±300 30±19 17.8±1.6 51 000±1 000 21 000±6 000 4 100±300 注:B/C用于表征污水可生化性,一般小于0.3视为可生化性差。 表 2 浓缩液不同温度下烧干后固相物质的元素种类及原子百分比
Table 2. Element type and atomic percent in concentrate dried out at different temperatures
温度/℃ 原子百分比/% C O Na Mg S Cl K Ca 其他 750 3.38 27.72 18.73 14.36 5.6 18.6 5.77 2.82 3.03 850 1.29 44.31 10.46 24.06 10.69 1.8 3.96 2.26 1.16 900 1.08 44.58 9.59 28.29 9.77 0.42 2.55 2.47 1.25 1 000 1.49 47.11 17.05 9.19 14.67 0.91 4.6 3.47 1.51 1 100 2.84 45.68 17.4 6.26 13.19 4.54 7.22 1.69 1.16 -
[1] HE R, WEI X M, TIAN B H, et al. Characterization of a joint recirculation of concentrated leachate and leachate to landfills with a microaerobic bioreactor for leachate treatment[J]. Waste Management, 2015, 46: 380-388. doi: 10.1016/j.wasman.2015.08.006 [2] HUNCE S Y, AKGUL D, DEMIR G, et al. Solidification/stabilization of landfill leachate concentrate using different aggregate materials[J]. Waste Management, 2012, 32(7): 1394-1400. doi: 10.1016/j.wasman.2012.03.010 [3] 郭冏. 渗沥液回喷焚烧炉的可行性探讨[J]. 环境卫生工程, 2013, 21(4): 22-23. doi: 10.3969/j.issn.1005-8206.2013.04.009 [4] ZHANG J, XIAN P, YANG L H, et al. Analysis of degradation by aerobic recharge for concentrated leachate[J]. Applied Mechanics & Materials, 2014, 675-677: 483-488. [5] TALALAJ I A, BIEDKA P. Impact of concentrated leachate recirculation on effectiveness of leachate treatment by reverse osmosis[J]. Ecological Engineering, 2015, 85(1): 185-192. [6] BIRCHLER D R, MILKE M W, MARKS A L, et al. Landfill leachate treatment by evaporation[J]. Journal of Environmental Engineering, 1994, 120(5): 1109-1131. doi: 10.1061/(ASCE)0733-9372(1994)120:5(1109) [7] 刘导明, 张璐, 王磊, 等. 机械蒸发处理垃圾渗滤液的试验研究[J]. 工业安全与环保, 2018, 44(4): 89-91. doi: 10.3969/j.issn.1001-425X.2018.04.022 [8] YUE D B, XU Y D, MAHAR R B, et al. Laboratory-scale experiments applied to the design of a two-stage submerged combustion evaporation system[J]. Waste Management, 2007, 27(5): 704-710. doi: 10.1016/j.wasman.2006.04.017 [9] LUKIC N, DIEEZEL L L, FROBA A P, et al. Economical aspects of the improvement of a mechanical vapour compression desalination plant by dropwise condensation[J]. Desalination, 2010, 264(1/2): 173-178. [10] XU J, LONG Y Y, SHEN D S, et al. Optimization of Fenton treatment process for degradation of refractory organics in pre-coagulated leachate membrane concentrates[J]. Journal of Hazardous Materials, 2016, 323: 674-680. [11] WANG H W, LI X Y, HAO Z P, et al. Transformation of dissolved organic matter in concentrated leachate from nanofiltration during ozone-based oxidation processes (O3, O3/H2O2 and O3/UV)[J]. Journal of Environmental Management, 2017, 191: 244-251. doi: 10.1016/j.jenvman.2017.01.021 [12] HILLES A H, ABU AMR S S, HUSSEIN R A, et al. Optimization of leachate treatment using persulfate/H2O2 based advanced oxidation process: case study: Deir El-Balah Landfill Site, Gaza Strip, Palestine[J]. Water Science and Technology, 2016, 73(1): 102-112. doi: 10.2166/wst.2015.468 [13] FERNANDES A, PACHECO M J, CIRÍACO L, et al. Review on the electrochemical processes for the treatment of sanitary landfill leachates: Present and future[J]. Applied Catalysis B: Environmental, 2015, 176-177: 183-200. doi: 10.1016/j.apcatb.2015.03.052 [14] WANG Y J, LI X Y, ZHEN L M, et al. Electro-Fenton treatment of concentrates generated in nanofiltration of biologically pretreated landfill leachate[J]. Journal of Hazardous Materials, 2012, 229-230(3): 115-121. [15] 陈新芳. DTRO处理垃圾渗滤液浓缩液的中试研究[J]. 工业用水与废水, 2018, 49(3): 41-44. doi: 10.3969/j.issn.1009-2455.2018.03.009 [16] 管锡珺, 赵亚鹏, 智雪娇, 等. 垃圾填埋场反渗透浓缩液回喷至附近垃圾焚烧厂焚烧研究[J]. 环境工程, 2016, 34(5): 123-125. [17] 赵晓峰. 渗滤液回喷处理技术在垃圾焚烧发电厂的应用[J]. 华电技术, 2015, 37(1): 64-68. doi: 10.3969/j.issn.1674-1951.2015.01.022 [18] ZHANG Q Q, TIAN B H, ZHANG X, et al. Investigation on characteristics of leachate and concentrated leachate in three landfill leachate treatment plants[J]. Waste Management, 2013, 33(11): 2277-2286. doi: 10.1016/j.wasman.2013.07.021 [19] LI J Y, ZHAO L, QIN L L, et al. Removal of refractory organics in nanofiltration concentrates of municipal solid waste leachate treatment plants by combined Fenton oxidative-coagulation with photo-Fenton processes[J]. Chemosphere, 2016, 146: 442-449. doi: 10.1016/j.chemosphere.2015.12.069 [20] 王庆国, 乐晨, 卓瑞锋, 等. 电化学氧化法处理垃圾渗滤液纳滤浓缩液[J]. 环境工程学报, 2015, 9(3): 1308-1312. [21] 熊祖鸿, 鲁敏, 胡大为, 等. 广东省典型生活垃圾焚烧飞灰的物化及固化特性[J]. 环境化学, 2014, 33(7): 1173-1179. [22] ZHAO Y C, SONG L J, LI G J. Chemical stabilization of MSW incinerator fly ashes[J]. Journal of Hazardous Materials, 2002, 95(1/2): 47-63. [23] HELENA R, AGNIESZKA C, SILVIE H K, et al. Enrichment and distribution of 24 elements within the sub-sieve particle size distribution ranges of fly ash from wastes incinerator plants[J]. Journal of Environmental Management, 2017, 203: 1169-1177. [24] QIU Q L, JIANG X G, CHEN Z L, et al. Microwave-assisted hydrothermal treatment with soluble phosphate added for heavy metals solidification in MSWI fly ash[J]. Energy & Fuels, 2017, 31(5): 5222-5232. [25] LIU Y S, ZHENG L T, LI X D, et al. SEM/EDS and XRD characterization of raw and washed MSWI fly ash sintered at different temperatures[J]. Journal of Hazardous Materials, 2009, 162(1): 161-173. doi: 10.1016/j.jhazmat.2008.05.029 [26] NAM S, NAMKOONG W. Irradiation effect on leaching behavior and form of heavy metals in fly ash of municipal solid waste incinerator[J]. Journal of Hazardous Materials, 2012, 199-200: 400-447. [27] 姜永海, 席北斗, 李秀金, 等. 垃圾焚烧飞灰熔融固化处理过程特性分析[J]. 环境科学, 2005, 26(3): 176-179. doi: 10.3321/j.issn:0250-3301.2005.03.036 [28] 许明磊. 垃圾焚烧过程受热面积灰烧结特性实验研究[D]. 杭州: 浙江大学, 2007. [29] SHIN M S, KIM H S, JANG D S, et al. A numerical and experimental study on a high efficiency cyclone dust separator for high temperature and pressurized environments[J]. Applied Thermal Engineering, 2005, 25: 1821-1835. [30] 王海泉. 生活垃圾焚烧处理电厂运行分析[D]. 广州: 华南理工大学, 2011. [31] 白贤祥, 张玉刚. 生活垃圾焚烧厂余热锅炉水冷壁高温腐蚀治理研究[J]. 环境卫生工程, 2018, 26(3): 68-74. doi: 10.3969/j.issn.1005-8206.2018.03.021 [32] 张焕亨. 李坑垃圾焚烧高温腐蚀试验研究[D]. 广州: 华南理工大学, 2013. [33] LI Q H, ZHANG Y G, MENG A H, et al. On-the-spot test of the slagging in a grate-circulating bed garbage incinerator superheater[J]. Journal of Engineering for Thermal Energy & Power, 2012, 27(1): 55-60. [34] XU M L, YAN J H, MA Z Y, et al. Particularities concerning sintered ash deposits along flue ways of CFB waste incinerators[J]. Power Engineering, 2006, 26(4): 550-553. [35] NIELSEN H P. The implications of chlorine-associated corrosion on the operation of biomass-fired boilers[J]. Progress in Energy & Combustion Science, 2000, 26(3): 283-298. [36] 潘葱英. 垃圾焚烧炉内过热器区HCI高温腐蚀研究[D]. 杭州: 浙江大学, 2004.