What could the entire cornstover contribute to the enhancement of waste activated sludge acidification? Performance assessment and microbial community analysis.
BACKGROUND
Volatile fatty acids (VFAs) production from waste activated sludge (WAS) digestion is constrained by unbalanced nutrient composition (low carbon-to-nitrogen ratio). Characteristics conditioning by extra carbon sources, normally in the mixture of raw solid, has been reported to be an efficient approach to enhance WAS acidification. However, little attention has been paid to the contributions of other adjustment forms. Moreover, the corresponding ecological estimation has not been investigated yet.


RESULTS
In this study, the feasibility of corn stover (CS) conditioning with three adjustment forms [pretreated straw (S), hydrolysate (H) and hydrolysate + straw (HS)] in improving VFAs production from WAS was demonstrated. It was observed that the highest VFAs yield was achieved in H co-digesting test (574 mg COD/g VSS), while it was only 392 mg COD/g VSS for WAS digesting alone. VFAs composition was strongly adjustment form-dependent, as more acetic (HAc) and propionic (HPr) acids were generated in CS_HS and S, respectively. High-throughput sequencing analysis illustrated that acid (especially HAc)-producing characteristic genera (Bacteroides,ProteiniclasticumandFluviicola) and HPr-producing characteristic genera (Mangroviflexus andPaludibacter) were detected by CS_HS and S conditioning, respectively.


CONCLUSIONS
Corn stover conditioning greatly upgraded the WAS acidification performance, especially for the CS_H adjustment form, and the VFAs yield gained was considerably larger than that previously reported. CS adjustment forms played an important role in structuring the innate microbial community in WAS. Canonical correlation analysis illustrated that characteristic genera, with better hydrolysis and acidification abilities, could be enriched by the feedstocks with certain content of cellulose, hemicellulose or their saccharification hydrolysates. Moreover, ecological estimation revealed that, as far as the entire CS (including S and H) per acre was concerned, the capacity of WAS treatment would reach that produced in a one million mts capacity wastewater treatment plants (WWTPs) per day. These findings may have crucial implications for the operation of WWTPs.
College of Environmental Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, China ; State Key Laboratory Breeding Base of Coal Science and Technology Co-founded by Shanxi Province and the Ministry of Science and Technology, Taiyuan University of Technology, Taiyuan, China.
Aijuan
A
Zhou
College of Architecture and Civil Engineering, Taiyuan University of Technology, Taiyuan, China.
Jiaguang
J
Zhang
College of Environmental Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, China.
Kaili
K
Wen
College of Environmental Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, China.
Zhihong
Z
Liu
College of Environmental Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, China.
Guoying
G
Wang
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Wenzong
W
Liu
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China ; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin, China.
Aijie
A
Wang
College of Environmental Science and Engineering, Taiyuan University of Technology, 030024 Taiyuan, China.
Xiuping
X
Yue
Adjustment form; Anaerobic digestion; Corn straw (CS); Ecological estimation; Volatile fatty acids (VFAs); Waste activated sludge (WAS)