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Environ Technol. 2016 Dec;37(24):3168-76. doi: 10.1080/09593330.2016.1181108. Epub 2016 May 12.

A grit separation module for inorganic matter removal from activated sludge: investigation on characteristics of split sludge from the module.

Chen YP1,2, Guo JS1,2, Wang J3, Yan P1,2, Ji FY4, Fang F4, Dong Y1,2.

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a Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing , People's Republic of China.
b Key Laboratory of Reservoir Aquatic Environment , Chinese Academy of Science , Chongqing , People's Republic of China.
c Chongqing Jianzhu College , Chongqing , People's Republic of China.
d Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE , Chongqing University , Chongqing , People's Republic of China.


A grit separation module was developed to prevent the accumulation of inorganic solids in activated sludge systems, and it achieved effective separation of organic matter and inorganic solids. To provide technical and theoretical support for further comprehensive utilization of split sludge (underflow and overflow sludge from the separation module), the characteristics of split sludge were investigated. The settling and dewatering properties of the underflow sludge were excellent, and it had high inorganic matter content, whereas the overflow sludge had higher organic matter content. The most abundant inorganic constituent was SiO2 (59.34%), and SiO2, Al2O3, and Fe2O3 together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe2O3, CaO, and MgO to SiO2 and Al2O3 was 0.245 in the inorganic component of the underflow sludge. The underflow sludge had the beneficial characteristics of simple treatment and disposal, and it was suitable for use as a base raw material for ceramsite production. The overflow sludge with higher organic matter content was constantly returned from the separation module to the wastewater treatment system, gradually improving the volatile suspended solid/total suspended solid ratio of the activated sludge in the wastewater treatment system.


Activated sludge; comprehensive utilization; grit accumulation; grit separation module; hydrocyclone separation

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