Effects of three microbial agents on wheat straw aerobic composting
ZHANG Yang1,2,, AI Weidang2,3,,, JIN Xiangdan3,4, FENG Haiyan1, ZHANG Liangchang2,3, WU Chongyang3 1.School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 2.National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing 100094, China 3.SPACEnter Space Science and Technology Institute, Shenzhen 518117, China 4.School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
Abstract:This experiment was designed to discuss the effects of different microbial agents on wheat straw degradation during the first aerobic composting stage. Three microbial agents(named as QD, DH and VT)were selected for the wheat straw and food waste aerobic composting, which were used as the main materials and nutrient additive, respectively. During the experiment, temperature, water content, physicochemical properties of extracts, volatile solid (VS) content and C/N ratio were studied, and the degradation efficiencies with different microbial agents were compared. The results showed that with QD, DH and VT addition the processes had all experienced heating, thermophilic and cooling phases, and the peak temperature reached 58.2, 54.7 and 53.7 ℃, and the high temperature period kept 9, 6 and 6 d, respectively. Water content and EC displayed the tendency of rising up at the beginning and declining in late. E4/E6, VS and C/N ratio showed a trend of decreasing. pH was stable at 8.44, 8.42 and 8.48, respectively. The reduction content of VS was 18.87%, 24.48% and 22.08%, respectively. In conclusion, QD can improve the composting temperature and meet the harmless requirements; DH can promote the mineralization of organic matter in the materials, and all the microbial agents have a positive influence on the formation and accumulation of humus in the composting. This experiment can provide the theoretical basis for screening and cultivating efficient bacterial strains for wheat straw composting, and also suggests some solutions for the resourceful treatment of biomass solid waste (particularly wheat straw) in CELSS. Key words:controlled ecological life support system/ wheat straw/ microbial agents/ aerobic composting.
图1堆肥装置示意图 Figure1.Schematic diagram of the composting reactor
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1.School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China 2.National Key Laboratory of Human Factors Engineering, China Astronaut Research and Training Center, Beijing 100094, China 3.SPACEnter Space Science and Technology Institute, Shenzhen 518117, China 4.School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China Received Date: 2020-05-21 Accepted Date: 2020-10-22 Available Online: 2021-02-22 Keywords:controlled ecological life support system/ wheat straw/ microbial agents/ aerobic composting Abstract:This experiment was designed to discuss the effects of different microbial agents on wheat straw degradation during the first aerobic composting stage. Three microbial agents(named as QD, DH and VT)were selected for the wheat straw and food waste aerobic composting, which were used as the main materials and nutrient additive, respectively. During the experiment, temperature, water content, physicochemical properties of extracts, volatile solid (VS) content and C/N ratio were studied, and the degradation efficiencies with different microbial agents were compared. The results showed that with QD, DH and VT addition the processes had all experienced heating, thermophilic and cooling phases, and the peak temperature reached 58.2, 54.7 and 53.7 ℃, and the high temperature period kept 9, 6 and 6 d, respectively. Water content and EC displayed the tendency of rising up at the beginning and declining in late. E4/E6, VS and C/N ratio showed a trend of decreasing. pH was stable at 8.44, 8.42 and 8.48, respectively. The reduction content of VS was 18.87%, 24.48% and 22.08%, respectively. In conclusion, QD can improve the composting temperature and meet the harmless requirements; DH can promote the mineralization of organic matter in the materials, and all the microbial agents have a positive influence on the formation and accumulation of humus in the composting. This experiment can provide the theoretical basis for screening and cultivating efficient bacterial strains for wheat straw composting, and also suggests some solutions for the resourceful treatment of biomass solid waste (particularly wheat straw) in CELSS.
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--> --> --> 受控生态生保系统(controlled ecological life support system，CELSS)通过对大气控制、温湿度控制、食物供应、水再循环和废物处理等技术整合，可保障航天员在地外环境中健康生活和有效工作，是未来地外星球基地长期稳定运行的必要保证[1]。CELSS依据地球生态圈的基本原理，在有限的密闭空间内构建了“人-植物-微生物-环境”自循环式闭路生态系统[1]。其中，植物作为关键功能部件，能够为航天员提供新鲜食物和氧气、吸收二氧化碳和净化水质。在CELSS中，通常选择小麦作为主要的粮食作物，不可避免地会产生大量的植物不可食部分，这部分固废的积累不仅会造成占用舱体空间、发酵腐败等安全卫生问题，还会造成大量资源(如水分、碳元素、氮元素、无机盐等)的浪费。如何高效处理并回收利用这类固体废物，维持CELSS中较高的物质循环利用率与闭合度，已成为CELSS中迫切需要解决的问题。 针对CELSS中小麦秸秆等固废资源化处理问题，美国和俄罗斯等国采用焚烧[2]和湿式氧化[3]等物化技术进行处理。物化技术稳定可靠、反应速率快，但存在着对设备要求高、能耗高、对系统瞬时冲击负荷大、产生氮氧化物而限制元素循环等缺点。生化处理技术则具有能耗低、反应过程温和以及能够有效实现各元素再生循环等优势。CHYNOWETH等[4]采用干式厌氧发酵工艺处理水稻秸秆、废纸和狗粮(模拟成员粪便)混合物，运行时间为23 d，有机物降解率达到了81.2%；并提出针对固废的预处理、后处理(沼渣好氧堆肥)和营养液植物栽培等方面的研究应作为未来研究的方向之一。欧洲太空局采用湿式厌氧消化工艺[5]将反应控制在水解酸化阶段而抑制产甲烷阶段，将有机底物转化为VFAs、氨氮和CO2用于后续的藻类系统和硝化系统使用。WHITAKER等[6]研制了固体高温好氧反应器用于处理志愿者产生的废物，包括粪便、厕纸、食物残渣和卫生废水等，操作温度为55~70 ℃，总固体降解率可达到74%。TIKHOMIROV等[7]通过蘑菇(真菌)培养和蚯蚓等腐生动物对植物不可食部分进行好氧堆肥处理，得到了类土壤基质并用于作物栽培。上述生化处理技术虽可一定程度上实现固废的稳定减容和资源回收，但也面临着设备尺寸较大、反应周期较长或仍需后续的好氧发酵等无害化处理的局限。而好氧堆肥技术作为无害化和资源化的处理方式，对碳氮等养分有较好的保全，可将固废转化为腐殖质，施用后能对植物生长起到促进作用，符合CELSS中物质循环再生的要求，因而受到广泛关注和研究。好氧堆肥技术是通过多种微生物的协同作用来完成物料的降解，因此，微生物的配比是影响好氧堆肥过程的关键因素[8]。有研究[9]表明，堆肥中接种微生物菌剂能使堆温快速升高，有效杀灭堆肥物料中的病原菌和杂草种子，显著促进堆肥腐熟，提高堆肥质量。另外，在CELSS内，由于微生物受到严格的控制和防护，其主要来自航天员体表和体内，种类及数量都无法满足堆肥启动要求。因此，添加一定的功能菌剂对于启动堆肥反应、促进堆肥腐熟和缩短堆制周期至关重要。目前，以微生物菌剂接种用于禽畜粪便和市政污泥相关方面的研究较多[9-10]，通常添加秸秆、木屑等物质起到平衡含水率、调节C/N和通气性等作用[11]，市面上也有多种针对这类固废的商业菌剂。然而，针对农业固废小麦秸秆降解处理的商用菌剂并不常见，且对于菌剂接种用于小麦秸秆堆肥降解效果的研究较少。 为实现CELSS中小麦秸秆等固废的资源化处理，提高系统物质闭合度，本研究以小麦秸秆为主要处理对象，添加厨余垃圾作为调整物料C/N比的营养调节剂，选取3种商业菌剂开展小试反应器强制通风好氧堆肥试验，探究接种菌剂对小麦秸秆好氧堆肥一次发酵阶段降解效果的影响；考察堆肥过程中各项参数变化，分析比较3种菌剂对小麦秸秆的处理效果，探讨不同菌剂在小麦秸秆好氧堆肥各个阶段的降解作用，以期为筛选研制高效降解小麦秸秆的微生物菌剂提供理论基础。
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