Enhancement of performance and stability of anaerobic co-digestion of waste activated sludge and kitchen waste by using bentonite

Abstract

There are large amounts of waste activated sludge (WAS) and kitchen waste (KW) produced every year in China. It has been confirmed that anaerobic co-digestion is an effective method to solve this problem. The targets of the present study were optimizing the digestive performances and clearing of the mechanism of bentonite addition by adding bentonite into digestive system. Group M (WAS: KW = 1:2, based on VS) presented higher cumulative methane yield (CMY), where the CMY increased from 19.8 to 36.3 mL/g VS with the bentonite dosage from 0 to 2 g/g VS. After bentonite addition, the lag phase of every digester presented an obvious decrease from 15.1 to 1.4 d. Furthermore, and the moderating effects on microbial community by bentonite. The addition of bentonite improved methane production, and it can also reduce the lag phase of methane production in co-digestion. What's more, bentonite addition increased the speed of pH recovery from 4.2–4.8 to normal level (7.0–8.0) and thus enhanced the system stability. The conclusion of this study can be used to guide practical engineering.

Lag Phase in the Anaerobic Co-Digestion of Sargassum spp. and Organic Domestic Waste

“…This lag phase is not merely preparatory but a dynamic, organized, adaptable and evolutionary phase [35]. A lower delay interval implies greater potential inside the AD [36].…”

Anaerobic digestion of urea pretreated water hyacinth removed from Lake Abaya; bio-methane potential, system stability, and substance conversion

“…The alkalinity of the anaerobic reactor can be defined as the tendency of the intermediate solutions to maintain stable buffer capacity caused by existing organic acids. 31 To achieve the constancy and neutralize VFAs, the total alkalinity of the system must be higher than 2000 mg L −1 , 32 unless it could affect the action of microbial groups during methane production. In this study, the alkalinity of the system at the beginning was 2200 mg L −1 , and it was in the range, but it fluctuated during the digestion period, as shown in Fig.…”

Two-stage banana leaves wastes utilization towards mushroom growth and biogas production

“…The pH after the AD process was 7.18 and 7.3 for fungal treated and untreated BL, respectively, which was slightly alkaline and suitable for the methanogenic process (Zhao et al 2019). After 40 d of the AD process, the volatile solid removal efficiencies were 4.1% and 5.6% for fungal treated and un-treated BL, respectively, and this suggests that the experiment would require more time for more organic matter removal in the process.…”