Abstract

Pyrolysis and hydrothermal liquefaction (HTL) are potential technologies for renewable energy production and waste valorization using municipal wastewater sewage sludge and other lignocellulosic biomass. However, the organic-rich aqueous pyrolysis liquid (APL) and HTL aqueous phase (HTL-AP) produced currently have no apparent use and are challenging to manage. Furthermore, the toxic organic compounds in them can be harmful to the environment. Anaerobic digestion (AD) may be a viable method to manage the liquids and recover energy in APL and HTL-AP in form of methane-rich biogas. Integrating thermochemical processes with AD could promote a circular economy by recovering resources and reducing environmental pollution. The challenge, however, is the presence of toxic compounds recalcitrant to anaerobic biodegradation such as phenols and nitrogen-containing organics that can inhibit methane-producing microbes. This review presents information on APL and HTL-AP characterization and biodegradability. Feedstock composition and process operational parameters are major factors affecting APL and HTL-AP composition, subsequent toxicity, and degradability. Feedstocks with high nitrogen content as well as increased thermochemical processing temperature and retention time result in a more toxic aqueous liquid and lower methane yield. Dilution and low AD organic loading are required to produce methane. More comprehensive APL and HTL-AP chemical characterization is needed to adopt suitable treatment strategies. Pretreatments such as overliming, air stripping, partial chemical oxidation, adsorption, and solvent extraction of toxic constituents as well as co-digestion and microbial acclimatization successfully reduce toxicity and increase methane yield.

Graphic abstract

中文翻译：

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污水污泥及类似生物质热解，水热液化制取液态水生产生物甲烷的现状

摘要

热解和水热液化（HTL）是使用市政废水污水污泥和其他木质纤维素生物质进行可再生能源生产和废物增值的潜在技术。但是，目前生产的富含有机物的水热解液（APL）和HTL水相（HTL-AP）尚无明显用途，并且难以管理。此外，其中的有毒有机化合物可能对环境有害。厌氧消化（AD）可能是一种可行的方法，可以管理液体并以富含甲烷的沼气形式回收APL和HTL-AP中的能量。将热化学过程与AD集成可以通过回收资源和减少环境污染来促进循环经济。然而，挑战 是对厌氧生物降解有害的有毒化合物的存在，例如可以抑制产甲烷微生物的酚和含氮有机物。这篇综述介绍了有关APL和HTL-AP表征及生物降解性的信息。原料组成和工艺操作参数是影响APL和HTL-AP组成，后续毒性和降解性的主要因素。氮含量高的原料，以及增加的热化学处理温度和保留时间会导致毒性更大的含水液体和较低的甲烷产率。产生甲烷需要稀释和低AD有机负荷。为了采用适当的治疗策略，需要更全面的APL和HTL-AP化学表征。预处理，例如超石灰，空气汽提，部分化学氧化，吸附，

图形摘要