Abstract: Disclosed is a method for preparing short-chain fatty acids having high propanoic acid content, comprising: mix sludge and kitchen wastes for pre-fermentation to produce substrates required for synthesis of propionic acid, and then add propionibacterium to conduct anaerobic continuous fermentation, content of propionic acid in the final fermentation broth is as high as 71.2% of the total acid.

Abstract: Disclosed is a method for biological denitrification of water body polluted by nitrates using sustained-release solid carbon sources comprising the following steps: add cassava lees into water body polluted by nitrates for denitrification of the waste water, It can achieve the purpose of biological nitrogen removal through slowly releasing organic carbons as carbon sources for microbial denitrification in the water by cassava lees and the cassava lees losing the carbon-releasing function can be naturally degraded in the environment without causing secondary pollution.