In order to deal with hydrothermal liquefaction wastewater (HTWW), a new anaerobic-aerobic continuous process was developed. The process, which included a sequence of Up-Flow Anaerobic Sludge Blanket (UASB) and downstream aerobic Continuously Stirred Tank Reactor (CSTR), was tested on the HTWW obtained from Waste to Fuel® demo plant developed by ENI s.p.a. [1]. Performance of the system was evaluated in term of methane yield and chemical oxygen demand (COD) abatement capability. Detailed fate of organic compounds was evaluated through different analytical techniques, highlighting main issues and potential of HTWW biological treatment. The system was fed with neat HTWW (189 gCOD L⁻¹) for 2.5 y, with variable organic loading rate (OLR) and minimal external inputs. UASB reactors converted most of HTWW organics into volatile fatty acids (VFA) and methane with concurrent precipitation of oily like insoluble, whereas aerobic CSTR removed VFA from anaerobic effluent. Under regime conditions (ORL equal to 0.5 gCOD L⁻¹ d⁻¹) COD decreased from 189 to 6.6 gCOD L^-1, showing 97 % COD abatement with the coupled anaerobic-aerobic treatment. Such a COD abatement was obtained by means of multiple effects, namely biomethanation, precipitation of organic matter and aerobic oxidation of fermentation products (VFA produced in anaerobic digestion) and subsequent aerobic oxidation (in downstream aerobic reactor). These effects accounted for 43, 40 and 17 % of the total COD decrease, respectively. Inhibition phenomena were the key challenge for improving methane yields and system productivities. The overall results confirmed that valorization of HTWW is a feasible task, albeit rather challenging.

为了处理水热液化废水（HTWW），开发了一种新的厌氧-好氧连续工艺。该工艺包括一系列上游厌氧污泥毯子（UASB）和下游好氧连续搅拌釜反应器（CSTR），该工艺在由ENI spa开发的Waste toFuel®演示工厂的HTWW上进行了测试[1]。根据甲烷产量和减少化学需氧量（COD）的能力评估了系统的性能。通过不同的分析技术对有机化合物的详细命运进行了评估，突出了HTWW生物处理的主要问题和潜力。给系统供应纯净的HTWW（189 gCOD L ^-1）保持2.5年，有机负载率（OLR）可变，外部输入最少。UASB反应器将大部分HTWW有机物转化为挥发性脂肪酸（VFA）和甲烷，同时出现油状沉淀，如不溶物，而好氧CSTR从厌氧废水中去除了VFA。在条件条件下（ORL等于0.5 gCOD L ^-1 d ^-1），COD从189降低到6.6 gCOD L ^-1，结合厌氧-好氧处理，可减少97％的COD。这种COD减排是通过多种作用获得的，即生物甲烷化，有机物沉淀和发酵产物的好氧氧化（厌氧消化中产生的VFA）和随后的好氧氧化（在下游好氧反应器中）。这些影响分别占总COD减少的43％，40％和17％。抑制现象是提高甲烷产量和系统生产率的关键挑战。总体结果证实，对HTWW进行估价是一项可行的任务，尽管颇具挑战性。