ABSTRACT

Anaerobic ponds have the potential to contribute to low carbon wastewater treatment, however are currently restricted by long hydraulic residence time (HRT) which leads to large land requirements. A two-stage anaerobic pond (SAP) design was trialled against a single-stage control (CAP) over four HRTs down to 0.5 days, to determine the lowest HRT at which the ponds could operate effectively. No statistical differences were observed in particulate removal between the ponds over all four HRTs, suggesting solids loading is not a critical factor in AP design. Significantly higher biogas production rates were observed in the SAP than the CAP at 1.5 d and 1.0 d HRT, and microbial community profiling suggests the two-stage design may be facilitating spatial separation of the anaerobic digestion process along reactor length. Hydrogenotrophic methanogensis dominated over aceticlastic, with acetate oxidisation a likely degradation pathway. Experimental tracer studies were compared to CFD simulations, with the SAP showing greater hydraulic efficiency, and differences more pronounced at shorter HRTs. Greater flow recirculation between baffles was observed in CFD velocity profiles, demonstrating baffles can dissipate preferential flow patterns and increase effective pond volume, especially at high flow rates. The study demonstrates the potential of APs to be operated at shorter HRTs in psychrophilic conditions, presenting an opportunity for use as pre-treatments (in place of septic tanks) and primary treatment for full wastewater flows. Two-stage designs should be investigated to separate the stages of the anaerobic digestion process by creating preferential conditions along the pond length.

 抽象的

厌氧池有潜力促进低碳废水处理，但目前受到长水力停留时间（HRT）的限制，这导致需要大量土地。对两阶段厌氧池 (SAP) 设计与单阶段控制 (CAP) 进行了四个 HRT（低至 0.5 天）的试验，以确定池塘可以有效运行的最低 HRT。在所有四种 HRT 中，池塘之间的颗粒去除率没有观察到统计差异，这表明固体负荷不是 AP 设计中的关键因素。在 1.5 天和 1.0 天的 HRT 下，SAP 中的沼气生产率明显高于 CAP，微生物群落分析表明，两阶段设计可能促进厌氧消化过程沿反应器长度的空间分离。氢营养型产甲烷作用优于醋酸盐，醋酸盐氧化是可能的降解途径。将实验示踪剂研究与 CFD 模拟进行比较，SAP 显示出更高的水力效率，并且在较短的 HRT 下差异更加明显。在 CFD 速度剖面中观察到挡板之间有更大的流量再循环，这表明挡板可以消除优先流动模式并增加有效的池体积，尤其是在高流速下。该研究表明，AP 在嗜冷条件下以较短的 HRT 运行的潜力，为用作预处理（代替化粪池）和全废水流的初级处理提供了机会。应研究两阶段设计，通过沿池塘长度创造有利条件来分隔厌氧消化过程的各个阶段。