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Nutrient removal in sludge extracts and protein production by cultivation of Candida utilis
Author(s) -
Zhou Xinyu,
Hu Wanrong,
Ran Chaogang,
Chen Jing,
Xie Tonghui,
Zhang Yongkui
Publication year - 2021
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6608
Subject(s) - yeast , nutrient , fermentation , single cell protein , chemistry , organic matter , biomass (ecology) , food science , dry matter , pulp and paper industry , biology , biochemistry , botany , agronomy , organic chemistry , engineering
BACKGROUND It is of great benefit to recycle excess sludge, which is rich in inorganic and organic nutrients, as the substrate material for yeast growth. This study focused on the disposal of residual liquid of sludge after pretreatment. Candida utilis was firstly chosen to be cultivated in the sludge hydrolyzate for simultaneous efficient nutrients removal and yeast utilization through aerobic process. RESULTS C. utilis cultivated in excess sludge hydrolyzate with 20 g L −1 glucose gained the highest dry weight (6.10 ± 0.15 g L −1 ) and crude protein yield (1807.68 ± 9.12 mg L −1 ). Meanwhile, the highest nutrient removal efficiency (TN: 88.5%; TP: 97.1%) was obtained in such conditions. The protein content in the yeast reached 366.7 mg g −1 , with all essential amino acids accounting for about 30%, which basically met the nutritional requirements of protein. According to the Excitation‐emission matrix spectra (EEMs) analysis, the yeast can consume most of the organic matter by the end of fermentation. CONCLUSION The alternative approach by applying Candida utilis for converting excess sludge into microbial biomass is very efficient when it comes to nutrients removal in excess sludge and producing proteins with a high content of essential amino acids. This study indicated that C. utilis could be an alternative strain to treat excess sludge hydrolyzate with addition of glucose at appropriate concentration. © 2020 Society of Chemical Industry (SCI)