Abstract
Biological nitrogen removal from wastewater is widely used all over the world on account of high efficiency and relatively low cost. However, nitrogen removal efficiency is not optimized when the organic matter has inadequate effect for the lack of a sufficient carbon source in influent. Although addition of an external carbon source (e.g., methanol and acetic acid) could solve the insufficient carbon source problem, it raises the operating cost of wastewater treatment plants (WWTPs). On the other hand, large amounts of sludge are produced during biological sewage treatment, which contain high concentrations of organic matter. This paper reviews the emerging technologies to obtain an internal organic carbon resource from sewage sludge and their application on improving nitrogen removal of low carbon/nitrogen wastewater of WWTPs. These are methods that could solve the insufficient carbon problem and excess sludge crisis simultaneously. The recovery of nitrogen and phosphorus from treated sludge before recycling as an internal carbon source should also be emphasized, and the energy and time consumed to treat sludge should be reduced in practical application.
Highlights
Nitrogen pollution in natural water is a serious problem worldwide, especially in developing countries such as China [1,2]
The results showed that anaerobic sludge fermentation under alkaline conditions increased the number of bacteria involved in hydrolysis and acidification, and reduced the number of methanogens, favoring competition of bacteria over methanogens, improving the production short-chain fatty acids (SCFAs)
The result revealed that SCFA production was significantly improved, and fermentation time was shortened compared to not adding nano zero-valent iron, which was because the solubilization of sludge, hydrolysis of solute, and acidification of hydrolysate were all strengthened by adding nano zero-valent iron
Summary
Huacai Wang 1 , Cancan Jiang 2,3 , Xu Wang 2,3 , Shengjun Xu 2,3 and Xuliang Zhuang 2,3, *. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
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