title: Effect of initial pH on anaerobic co-digestion of kitchen waste and cow manure.
abstract: This study investigated the effects of different initial pH (6.0, 6.5, 7.0, 7.5 and 8.0) and uncontrolled initial pH (CK) on the lab-scale anaerobic co-digestion of kitchen waste (KW) with cow manure (CM). The variations of pH, alkalinity, volatile fatty acids (VFAs) and total ammonia nitrogen (NH4(+)-N) were analyzed. The modified Gompertz equation was used for selecting the optimal initial pH through comprehensive evaluation of methane production potential, degradation of volatile solids (VS), and lag-phase time. The results showed that CK and the fermentation with initial pH of 6.0 failed. The pH values of the rest treatments reached 7.7-7.9 with significantly increased methane production. The predicted lag-phase times of treatments with initial pH of 6.5 and 7.5 were 21 and 22 days, which were 10 days shorter than the treatments with initial pH of 7.0 and 8.0, respectively. The maximum methane production potential (8579 mL) and VS degradation rate (179.8 mL/g VS) were obtained when the initial pH was 7.5, which is recommended for co-digestion of KW and CM.
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Zhai
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; College of Forestry, Northwest A&F University, Shaanxi, Yangling 712100, China.
authors.forename: Dongxue
authors.initials: D
authors.lastname: Yin
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China. Electronic address: ygh@nwsuaf.edu.cn.
authors.forename: Gaihe
authors.initials: G
authors.lastname: Yang
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China.
authors.forename: Xiaojiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China.
authors.forename: Guangxin
authors.initials: G
authors.lastname: Ren
authors.affiliation: College of Agronomy, Northwest A&F University, Shaanxi, Yangling 712100, China; Research Center for Recycling Agriculture Engineering Technology of Shaanxi Province, Shaanxi, Yangling 712100, China.
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Feng
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D056804:Biofuels / Q000032:analysis*; D019149:Bioreactors; D002417:Cattle; D005735:Garbage; D006863:Hydrogen-Ion Concentration; D008372:Manure / Q000032:analysis*; D008697:Methane / Q000032:analysis*; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D008372:Manure; D008697:Methane
keywords: Anaerobic co-digestion; Cow manure; Initial pH; Kitchen waste; Modified Gompertz equation