-
我国西北干旱地区水资源短缺,生活污水再生回用农业技术应用广泛,但污水处理厂的生活污泥缺乏合理的处置方式。目前,污泥处置方法主要有物理填埋、焚烧和污泥堆肥,填埋和焚烧均对生态环境有一定的污染,而污泥堆肥可以在高温发酵过程中杀死病原菌,其最终产品可以作为有机肥料或土壤改良剂[1]。这既解决了城市污泥处置难的问题,又可为农业生产、城市绿化、苗圃育苗等提供肥料[2]。因此,污泥堆肥处置是有机物循环再利用的有效途径。我国西北干旱地区生活污泥利用离心技术脱水后的含水率在90%左右,而经过压滤板压滤后的含水率仍高达65%~75%,高含水率导致污泥在堆肥过程中存在升温和腐熟慢,养分损失多,而且还容易产生有毒有害气体的问题。因此,西北干旱地区污泥堆肥过程中亟需解决高含水率污泥升温速度慢的问题。
污泥好氧堆肥的升温速度和成品质量受添加辅料因素的影响。研究表明,污泥好氧堆肥辅料为稻草和秸秆时升温快,为锯末时氮素损失小[3-6]。秸秆小粒径比大粒径更有利于保存堆肥产品的养分;污泥与秸秆体积比1∶2时升温速度和腐熟度较好,堆肥产品中养分含量随着污泥和秸秆比例升高而增大,污泥堆肥处理成本也随之升高[7-9]。MAZDAK等[10]和ZHANG等[11]发现,适宜的翻抛工艺可以解决堆肥升温慢、效率低、成品质量差的问题。可见,污泥与辅料的配比、粒径及翻抛工艺是影响污泥堆肥升温速率和堆肥产品质量的重要因素。在我国,已有研究多集中于不同辅料的选择、配比和粒径等单因素对污泥堆肥升温速率和堆肥产品质量的影响方面,而综合这些因素对西北干旱地区污泥好氧堆肥过程中各项指标动态变化规律影响的研究相对较少。
本研究在我国西北干旱区通过开展3因素3水平的正交实验,研究玉米秸秆比例、粒径及翻抛工艺对污泥堆肥堆体内部温度、pH、电导率及水分的影响,筛选适宜该地区污泥堆肥的玉米秸秆添加比例、粒径及翻抛工艺,以期为我国西北干旱地区生活污泥高效堆肥提供参考。
辅料及工艺参数对干旱地区污泥堆肥物理指标动态变化的影响
Effects of auxiliary materials and pile-turning technique on the dynamical changes of some physical index of sludge composite in northwest arid region
-
摘要: 针对我国西北干旱地区污泥堆肥过程中存在升温速度慢和缺少适宜堆肥技术参数的问题,通过大型条垛式污泥堆肥正交实验,研究堆肥过程中堆体的温度、pH、电导率、含水率的动态变化过程,以期明确适宜该地区的污泥堆肥技术参数。结果表明,当玉米秸秆配比为15%时,堆体的升温速度达17.3 ℃∙d−1,最高温度可达75 ℃以上;当秸秆粒径为5 cm时,高温持续时间最长,达22 d;堆体的电导率随着秸秆配比的增加呈增加的趋势,堆肥结束后以秸秆配比15%的电导率值最大。从水分变化来看,堆肥10 d后,污泥先静置6 d后翻抛的堆体上层含水率高,而常规翻抛的堆体各层含水率在15 d后呈现下层>上层>中层的垂直空间分布。总体而言,玉米秸秆粒径对堆体温度影响最大,而玉米秸秆配比对堆体含水率影响最大。西北干旱区污泥条垛式堆肥最优技术参数为添加5 cm粒径的玉米秸秆15%,完全混合先静置6 d后进行翻抛。本研究结果可为我国西北干旱地区生活污泥高效堆肥提供参考。Abstract: The objectives of this research were to clarify the influence of auxiliary materials and pile-turning technique on the dynamic change of physical index of sludge composting in northwest arid region, and to provide suitable technical parameters for organic fertilizer production with domestic sludge. The temperature, pH value, electrical conductivity, moisture content and its dynamic change in the upper, middle and lower layers of the windrow were studied by a large windrow composting system with an orthogonal experiment of 9 strips including 3 factors (ratio of auxiliary materials, particle size of auxiliary materials and turning-over process) and 3 levels. Results showed that the rate of temperature increase of compost was as fast as 17.3 ℃·d−1 and the highest temperature reached over 75 ℃ with 15% straw ratio. The duration of high temperature period got 22 days with the straw particle size of 5 cm. The electrical conductivity (EC) of the compost increased with the increase of the straw ratio, and the maximum value of EC at the end of experiment was achieved with 15% straw ratio. The moisture content at upper layer was higher with the treatment of conventional turning-over after standing for 6 d within composting 10 days and then gradually tended to be consistent among different layers after composting 30 days. However, the moisture content of each layer showed a vertical gradient of lower layer > upper layer > middle layer with conventional turning-over after composting 15 days. The maximum affecting factor on sludge composting temperature was corn straw particle size, while the maximum affecting factor on sludge composting moisture content was corn straw ratio during sludge composting. In a word, the optimal composting parameters for the sludge composting system in the northwest arid region are 15% corn stalks, 5 cm particle size of the stalks, and conventional turning-over after standing for 6 days. The results of this study can provide a reference for sludge window composting in the arid region of northwest China.
-
表 1 原材料初始理化参数
Table 1. Initial physicochemical parameters and mass fraction of raw materials
供试原料 含水率/% 有机质/% 全氮/% 全碳/% 砷/(mg∙kg−1) 镉/(mg∙kg−1) 汞/(mg∙kg−1) 铅/(mg∙kg−1) 铬/(mg∙kg−1) 污泥 74.18 62.25 4.85 31.05 10.70 0.28 7.58 33.00 79.50 秸秆 11.61 81.72 1.08 42.14 — — — — — 表 2 正交实验设计
Table 2. Design of orthogonal tests
处理编号 玉米秸秆配比/% 玉米秸秆粒径/cm 翻抛流程 T1 5 5 静置6 d翻抛 T2 5 3 常规翻抛 T3 5 15~20 曝气常规翻抛 T4 10 5 曝气常规翻抛 T5 10 3 静置6 d翻抛 T6 10 15~20 常规翻抛 T7 15 5 常规翻抛 T8 15 3 曝气常规翻抛 T9 15 15~20 静置6 d翻抛 表 3 堆体有效积温极差分析
Table 3. Analysis of effective accumulated temperature range of reactor
℃ 因素 玉米秸秆配比 玉米秸秆粒径 翻抛工艺 1j$\overline K $ 30 400 30 320 28 888 2j$\overline K $ 29 340 30 182 30 352 3j$\overline K $ 29 358 28 596 29 858 j$\overline R $ 3 180 5 172 4 392 表 4 含水率减量化极差分析
Table 4. Range analysis of water content reduction of compost
% 因素 玉米秸秆配比 玉米秸秆粒径 翻抛流程 1j$\overline K $ 13.84 18.07 23.82 2j$\overline K $ 20.96 17.74 19.53 3j$\overline K $ 27.86 26.87 19.32 Rj 42.06 27.40% 13.50 -
[1] 郭广慧, 陈同斌, 杨军, 等. 中国城市污泥重金属区域分布特征及变化趋势[J]. 环境科学学报, 2014, 34(10): 2455-2461. [2] 麦旭东, 谭军利, 王西娜, 等. 中国城市生活污泥堆肥技术标准及政策分析[J]. 宁夏工程技术, 2020, 19(3): 274-277. doi: 10.3969/j.issn.1671-7244.2020.03.018 [3] 贺亮, 赵秀兰, 李承碑. 不同填料对城市污泥堆肥堆体温度动态变化影响[J]. 西南农业大学学报(自然科学版), 2016(3): 389-392. [4] GAO W X, LIANG J F, PIZZUL L, et al. Evaluation of spent mushroom substrate as substitute of peat in Chinese biobeds[J]. International Biodeterioration & Biodegradation, 2015, 98: 107-112. [5] MAHNAZ N, AMIR H N, BIJAN B, et al. Respiration and enzymatic activities as indicators of stabilization of sewage sludge composting[J]. Waste Management, 2015, 39: 104-110. [6] FEI C, SIGRID P, AHMED M E, et al. Kinetics of natural organic matter (NOM) removal during drinking water biofiltration using different NOM characterization approaches[J]. Water Research, 2016, 104: 361-370. [7] 贾程. 污泥与秸秆堆肥过程中氮、磷形态变化研究[D]. 陕西: 西北农林科技大学, 2008. [8] 鲍博, 唐琦, 刘梅, 等. 水稻秸秆添加对污水处理厂污泥好氧堆肥效果的影响[J]. 安徽农业科学, 2020, 48(23): 88-90. [9] 李清秀, 张雁秋, 李向东. 污泥与稻草混合堆肥研究[J]. 江苏农业科学, 2008(6): 260-261. doi: 10.3969/j.issn.1002-1302.2008.06.117 [10] MAZDAK R, MEHRDAD A, BABAK P. Comparative evaluation of aeration methods for municipal solid waste composting from the perspective of resource management: A practical case study in Tehran, Iran[J]. Journal of Environmental Management, 2016, 184: 528-534. [11] ZHANG J Y, CAI X, QI L, et al. Effects of aeration strategy on the evolution of dissolved organic matter (DOM) and microbial community structure during sludge bio-drying[J]. Applied microbiology and biotechnology, 2015, 99(17):7321-7331. [12] 吕中秀. 土壤环境监测过程中有机质测定方法对比分析[J]. 山东化工, 2021, 50(18): 291-292. doi: 10.3969/j.issn.1008-021X.2021.18.107 [13] 汪欣, 向兆, 李策, 等. 全自动凯氏定氮仪测定土壤全氮含量方法的优化探索[J]. 山东农业大学学报(自然科学版), 2020, 51(3): 438-440. [14] 中华人民共和国国家质量监督检验检疫总局、中国国家标准化管理委员会. 土壤质量 总汞、总砷、总铅的测定 原子荧光法 : GB/T 22105.2-2008[S]. 质检出版社, 2008. [15] 谢银凤. 石墨炉原子吸收法测定固废和土壤中的总铬[J]. 广州化工, 2020, 48(18): 80-81. doi: 10.3969/j.issn.1001-9677.2020.18.029 [16] 耿纯梅, 张瑞, 刘建国, 等. 2013年-2017年巴彦淖尔市农田土壤中铅、镉、铬监测结果分析[J]. 中国卫生检验杂志, 2019, 29(1): 112-113. [17] 杨立敏. 污泥堆肥过程温度与酶活性动态变化规律研究[J]. 广东化工, 2020, 47(16): 134-136. doi: 10.3969/j.issn.1007-1865.2020.16.054 [18] 中华人民共和国卫生部、中国国家标准化管理委员会. 粪便无害化卫生要求: GB 7959-2012[S]. 质检出版社, 2012. [19] 陈同斌, 黄启飞, 高定, 等. 城市污泥好氧堆肥过程中积温规律的探讨[J]. 生态学报, 2002(6): 911-915. doi: 10.3321/j.issn:1000-0933.2002.06.016 [20] 康军, 张增强, 张维, 等. 玉米秸秆添加比例对污泥好氧堆肥质量的影响[J]. 武汉理工大学学报, 2010, 32(2): 172-176. doi: 10.3963/j.issn.1671-4431.2010.02.041 [21] 曾光明, 黄国和, 袁兴中. 堆肥环境生物与控制[M]. 北京: 科学出版社, 2006.117-119 [22] MENG L Q, LI W G, ZHANG S M, et al. Feasibility of co-composting of sewage sludge, spent mushroom substrate and wheat straw[J]. Bioresource Technology, 2017, 226: 39-45. [23] 中华人民共和国住房和城乡建设部. 城镇污水处理厂污泥处置 农用泥质: CJ/T 309-2009[S]. 质检出版社, 2009. [24] HACHICHA R, HACHICHA S, TRABELSI I, et al. Evolution of the fatty fraction during co-composting of olive oil industry wastes with animal manure: maturity assessment of the end product[J]. Chemosphere, 2009, 75(10): 1382-1386. doi: 10.1016/j.chemosphere.2009.02.064 [25] 李思敏, 赵阳悦, 唐锋兵. 辅料配比对市政污泥堆肥效果的影响[J]. 当代化工, 2020, 49(4): 564-567. doi: 10.3969/j.issn.1671-0460.2020.04.016 [26] 孟云姣, 唐锋兵, 张娟, 等. 不同调理剂协同市政污泥好氧堆肥试验研究[J]. 工业用水与废水, 2020, 51(1): 82-87. doi: 10.3969/j.issn.1009-2455.2020.01.020 [27] 程永高. 邢台市污水处理厂污泥好氧堆肥的研究[D]. 石家庄: 河北科技大学, 2012. [28] 李欢, 金宜英, 聂永丰, 等. 污泥超声处理及其在好氧消化中的应用[J]. 环境科学, 2017, 35(8): 22-23. [29] 徐灵, 王成端, 姚岚. 污泥堆肥过程中主要性质及氮素转变[J]. 生态环境, 2008(2): 602-605. [30] 周海宾, 高定, 陈同斌, 等. 调理剂配比对污泥好氧发酵脱水和处理成本的影响[J]. 中国给水排水, 2012, 28(19): 103-105. doi: 10.3969/j.issn.1000-4602.2012.19.028