Using wastewater to improve wastewater treatment: Kill two birds with one stone

Significance

Over the past few years, economic dynamics have resulted in the growth of new towns and cities as well as the expansion of the already existing ones. This has resulted in tremendous increase in urban population leading to congestion in some cities and towns. Therefore, it has increased consumption of water and generation of more wastewaters. However, the need to protect the environment from such pollutants have compelled urban residents as well as various stakeholders to treat the wastewaters before being discharged.

Generally, removal of biological nutrients from wastewaters depends on the carbon content. This is because it allows efficient denitrification process and phosphorus uptake. However, due to inadequate carbon sources in most of the urban water treatment plants, external carbon sources have been identified as promising solutions. This includes methanol, acetate, and glucose among others. A typical biological nutrient removal process undergoes various transformation including nitrification and denitrification processes to recover nitrogen and phosphorus. Unfortunately, they have not met the required performance level owing to numerous challenges. In a recently published literature, volatile fatty acids have been used as a carbon source for enhancing the performance of biological nutrient removal processes due to its recoverability ease through anaerobic fermentation.

Recently, Tongji University scientists: Dr. Xiong Zheng and his colleagues from the School of Environmental Science and Engineering developed a novel method for enhancing the performance of municipal biological nutrient removal processes by using a suitable carbon source derived from kitchen wastewater. Their managed to improve phosphorus uptake and short-cut nitrification-denitrification process simultaneously. The work is published in the journal, Chemical Engineering Journal.

Briefly, the authors commenced their experimental work by anaerobically fermenting kitchen wastewater to find optimal conditions for volatile fatty acid production. Then, they investigated the feasibility of using the produced volatile fatty acid as an extra carbon source and compared its performance to that of the unfermented kitchen wastewater. Eventually, they examined the full-scale applications of the fermented liquid in municipal wastewater biological nutrient removal processes.

The authors observed that anaerobic fermentation of kitchen wastewater significantly enhanced the production of volatile fatty acid and in particular propionic and acetic acids. As a result, the fermentation liquid exhibited higher biological nitrogen and phosphorus removal efficiencies as compared to the unfermented kitchen wastewater. For the full-scale application of the alkaline fermentation of kitchen wastewater in municipal wastewater biological nutrient removal, it was noted that it resulted in higher phosphors uptake as compared to commonly used carbon sources like acetic acid.

Tongji University researchers successfully achieved short-cut nitrification and denitrification that significantly enhanced the nitrogen and phosphorus removal efficiencies. Therefore, the study will reduce wastewater pollution in urban centers while at the same time increasing the soil and water nutrients level that can be used for other economic benefits like agriculture.

Using wastewater to improve wastewater treatment: Kill two birds with one stone - Advances in Engineering

Using wastewater to improve wastewater treatment: Kill two birds with one stone - Advances in Engineering

About the author

Dr Xiong Zheng is an Associate Professor of environmental engineering at the Tongji University, China. He graduated in environmental engineering in 2007 at the Nanjing University, and then got a PhD in environmental engineering in 2013 at the Tongji University. In 2017-18 he was Visiting Scholar at the Arizona State University’s Biodesign Swette Center for Environmental Biotechnology where he studied the environmental microbiology in membrane water treatment system. He currently is a committee member of International Water Association (IWA) Young Water Professionals (YWP) China.

Xiong’s research interest currently focuses on environmental microbiology in water and sludge treatment, and behaviors and removal of contaminants of emerging concern in water and sludge treatment system. He authored/co-authored more than 50 scientific papers in international refereed journals, such as Environmental Science & Technology and Water Research. The total citation of his research publications is up to 2000 with the h-index of 22.

Reference

Zheng, X., Zhou, W., Wan, R., Luo, J., Su, Y., Huang, H., & Chen, Y. (2018). Increasing municipal wastewater BNR by using the preferred carbon source derived from kitchen wastewater to enhance phosphorus uptake and short-cut nitrification-denitrificationChemical Engineering Journal, 344, 556-564.

Go To Chemical Engineering Journal

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