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

Chen, You-Peng, Guo, Jin-Song, Wang, Jing, Yan, Peng, Ji, Fang-Ying, Fang, Fang, Dong, Yang
Environmental technology 2016 v.37 no.24 pp. 3168-3176
activated sludge, aluminum oxide, calcium oxide, dewatering, environmental technology, iron, magnesium oxide, organic matter, raw materials, total suspended solids, wastewater treatment
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 SiO ₂ (59.34%), and SiO ₂, Al ₂O ₃, and Fe ₂O ₃ together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe ₂O ₃, CaO, and MgO to SiO ₂ and Al ₂O ₃ 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.