Kinetics and microbial community analysis of sludge anaerobic digestion based on Micro-direct current treatment under different initial pH values

Globally, wastewaters emanating from edible oil manufacturers contain high organic (BOD & COD) and phosphate loads and known for creating shock-loading problems for the receiving wastewater treatment installations. Discharge of poor quality final effluents also negatively impact on and cause eutrophication of natural water sources such as rivers and dams. In South Africa, a large concentration ofthe edible industries are localized in the Pietermaritzburg region of Kwa-Zulu Natal and have been regularly associated with discharge of poor quality final effluent that did not subscribe to municipal regulation standards. Current treatment of choice for wastewater's in the edible oil industry have been limited primarily to dissolved air flotation combined with the use of chemical coagulants or physical separation of oil and grease via a gravity fat trap and subsequent pH correction. These physico-chemical methods have achieved limited success and the emulsified grease tends to clog sewer pipes and pumps producing poor quality effluents. Therefore, the aim of the current research was to develop suitable treatment technology focussing on adapting activated sludge process to remediate edible oil effluents and determine the microbial community of the process using novel molecular techniques.

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Succession of microbial community in anaerobic digestion of dairy manure induced by manure-derived biochar

Environmental Engineering Research ◽

10.4491/eer.2020.001 ◽

2020 ◽

Vol 26 (1) ◽

Author(s):

Hyun Min Jang ◽

Jeff Brady ◽

Eunsung Kan

Keyword(s):

Electron Transfer ◽

Microbial Community ◽

Anaerobic Digestion ◽

Community Analysis ◽

Dairy Manure ◽

Microbial Community Analysis ◽

Methane Yield ◽

Lag Phase ◽

Interspecies Electron Transfer ◽

Syntrophic Bacteria

The present study investigates possible roles of manure-derived biochar (MBC) in anaerobic digestion (AD) of dairy manure. Addition of MBC led to an increase in cumulative methane yield and a decrease in lag phase under all tested conditions (concentration of MBC: 1 and 10 g/L, temperature: 20, 35 and 55°C). For example, the cumulative methane yield in the mesophilic AD with 10 g/L MBC were 24.51% higher than that of the AD without MBC. Additionally, lag phage of mesophilic AD with 10 g/L MBC decreased from 2.08 d to 1.52 d. Microbial community analysis indicated that the addition of MBC to mesophilic and thermophilic AD of dairy manure increased the relative abundance of Ruminofilibacter which related to the hydrolysis. In addition, the addition of MBC to AD potentially stimulated the growth of syntrophic bacteria (e.g., genera Clostridium, Syntrophomonas and Syntrophus) and hydrogenotrophic methanogens (e.g., genera Methanobacterium, Methanolinea and Methanomassiliicoccus). Furthermore, microbial community analysis also suggested that mediate interspecies electron transfer and direct interspecies electron transfer would be accelerated by addition of MBC which showed high electrical conductivity (3230 μS/cm).

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