市政污泥与秸秆混合酶解的产能工艺研究及其碳排放评价

There are 21 wastewater treatment plants in Gansu province. It is the future development goal that the wastewater treatment plant will be built in every county, and about 86 plants in Gansu province. This is serious question that the large amounts of sludge are produced in each wastewater treatment plant on every day. At present, the disposal methods of municipal sludge are usually sanitary landfill and accumulation in the open air. These methods caused the large of land wasted and secondary pollution of environment. Moreover, more than 40% of the crop straw was disposed by burning on the field in Gansu province, causing the environmental problems such as air pollution, soil mineralization and so on. In view of the above questions, according to sludge disposal principle of country and referring to sludge treatment experience and technology abroad, the research on digesting sludge with straw is proposed. Research purpose is that the organic matter converts the available biogas through anaerobic digestion, using sludge microorganisms, organic matter of sludge and the carbon in the straw. At the same time, the enzyme is added in the experimental process for improving reaction. Then, technology practicability and environmental security of digestion leftovers will be evaluation according to land application experiment. In the end, operation control parameters and the process flow of utilizing sludge and straw will be obtain, meanwhile, the process of carbon emissions will be evaluate and the future value of the technology application will be discuss. Through the research of this project, the sludge and straw will become the resource and energy, the harm and effects of the environment will be reduced because of mishandling the sludge and straw, and that operational parameters of experiment are as reference data for energy source engineering.

甘肃境内现有污水处理厂21座，未来发展目标是86个县都有污水处理厂。每座污水处理厂每日产生大量污泥，污泥处理是一个大问题。甘肃省内污泥处置的常用方法是卫生填埋和露天堆积。这些方法既浪费土地资源又容易造成环境的二次污染。而省内超过40%的农作物秸秆通过田间焚烧进行处置，造成了空气环境污染、土壤矿化等问题。针对上述情况，根据国家的污泥处置原则，参考国外的污泥处理经验和技术，提出将污泥和秸秆混合消化，充分利用污泥中的微生物、有机物和秸秆中的碳，将混合物中的有机质转化为可利用的生物气，同时，添加酶强化反应。然后，将消化后的剩余物土地应用，评价剩余物的环境安全性和实用性。最终获得污泥、秸秆循环利用的工艺流程和运行控制参数，并对该工艺进行碳排放评价，探讨工艺的未来应用价值。通过该项目的研究，使污泥、秸秆可以实现资源化、能源化，减少污泥、秸秆处置不当对环境造成的影响和危害，为新型能源工程提供参考数据。

我国秸秆、污泥产量巨大，需要回收利用。由于我国污泥中的有机物含量较低，但秸秆中含有大量的以纤维素为主的碳源，通过添加秸秆来补充碳源，并和污泥进行共消化，产生沼气以达到资源化利用的目的。.研究组探究了污泥秸秆共消化的影响因素。结论有：①使用响应面法分析并进行批次试验，结果为：污泥秸秆 TS 比 2:1；进料 TS 浓度 40g/L；预处理 NaOH 浓度为 2%。②接种率为 30%时，反应器易发生酸化；接种率为 50%时，甲烷产量可达 143.38ml/gVS，相比污泥为底物、未预处理的混合底物提高了 372.73%， 172.02%。③通过对反应器在不同 SRT 下的甲烷产量，出料 SCOD，碱度，VFA 等指标的分析，确定半连续流反应器在 SRT 大约为 8 天左右时运行效果最佳，产气效率最高。.研究组通过批次实验验证热碱超声预处理、沼液回流、外源酶投加对秸秆污泥厌氧消化的影响。结论有：①热碱超声预处理对二者混合厌氧消化产气有明显强化作用，甲烷产量达800.7 mL。②反应产物重金属含量满足我国污泥标准限值，理论上可作为农业污泥。③沼液回流能有效强化二者共消化产沼气。50%沼液回流率的甲烷产量为797.5 mL，为最佳回流率。④单一酶批次实验得出最优纤维素酶、蛋白酶投加量为80mg/gTS， 80mg/gTS。⑤复合酶最佳酶配比为蛋白酶:纤维素酶=1:2（26.67mg中性蛋白酶/g TS，53.33mg纤维素酶/g TS），其累积产甲烷量达373.05 mL。.研究组对反应器内微生物群落进行高通量测序，结论有：①高、低负荷基质条件下（20gTS/L/d）、（12gTS/L/d），平均日产气量约为4.1L、 2.1L。②高负条件下的优势菌群为： 51.06% Bacteroidetes、11.65% Firmicutes、8.25% Euryarchaeota。③两种基质条件下都检测到12种产甲烷菌属，分属氢营养型、甲基营养型、乙酸营养型，说明整个消化体系的代谢途径较丰富，建立了较平衡的缓冲体系。④添加外源酶能有效扩大秸秆污泥基质的降解，优势产甲烷古菌有Methanosaeta，Candidatus Methanofastidiosum，Methanocorpusculum等。