Abstract

A single-stage Anaerobic Membrane Bioreactor (AnMBR) for the treatment of cheese whey and its co-digestion with cattle slurry was investigated with the aim of potentially recovering water and energy from the wastewater. A 9 L reactor coupled to an ultrafiltration flat sheet membrane module in an external configuration was employed. This configuration enabled the proper separation of solids from permeate. Cheese whey was stored at room temperature and its chemical oxygen demand (COD) varied between 51 and 80 g/L. The reactor was operated at an average hydraulic retention time (HRT) of 15 days and at an organic loading rate (OLR) of 1.2–8.4 kg COD/(m³·day). During operation a COD removal average of 91% ± 7% was achieved. The biogas production ranged from 0.2 to 0.9 m³ biogas/kg COD removed and its methane content was 51–73%. From these results, a potential energy recovery of 2.4 kWh/kg COD removed was calculated. Microbial community analysis showed that bacteria belonging to the orders Bacteroidales and Clostridiales became the most prevalent. The bioreactor was dominated by acetotrophic methanogenesis. The co-digestion of cheese whey with cow manure (3:1) did not decrease NaOH consumption for pH control. Water reuse for cleaning purposes is possible if permeate pH is maintained at 6. Prior to the scaling-up of the system, a pilot scale test would be necessary to optimise membrane performance. The use of AnMBR technology at a real scale would be appropriate since it is a compact technology which permits both energy and potential water recovery after permeate post-treatment, thus constituting a further step towards the establishment of a broader a circular economy approach.

Graphical Abstract

中文翻译：

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厌氧膜生物反应器（AnMBR）用于处理干酪乳清，以潜在回收水和能量

摘要

研究了一种单级厌氧膜生物反应器（AnMBR），用于处理干酪乳清及其与牛粪浆的共消化，目的是从废水中回收水和能量。使用在外部配置中连接至超滤平板膜组件的9L反应器。这种配置可以使固体与渗透物正确分离。干酪乳清在室温下储存，其化学需氧量（COD）在51至80 g / L之间变化。反应器的平均水力停留时间（HRT）为15天，有机负荷率（OLR）为1.2–8.4 kg COD /（m ³ ·day）。在操作过程中，平均COD去除率为91％±7％。沼气产量为0.2至0.9 m ³去除的沼气/ kg COD及其甲烷含量为51-73％。根据这些结果，计算出去除了2.4 kWh / kg COD的潜在能量回收。微生物群落分析表明属于订单细菌Bacteroidales和梭菌成为最流行的。该生物反应器主要是由营养萎缩的甲烷生成。奶酪乳清和牛粪（3：1）的共同消化不会减少用于控制pH的NaOH消耗。如果渗透液的pH值保持在6，则可以重复使用水进行清洁。在放大系统之前，有必要进行中试规模测试以优化膜性能。在实际规模上使用AnMBR技术将是适当的，因为它是一种紧凑的技术，可以在渗透后处理后同时回收能量和潜在的水，从而构成了朝着建立更广泛的循环经济方法迈出的又一步。

图形概要