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

Abstract

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.

Characteristics of sand recovered from the municipal wastewater treatment plant

“…In order to reduce the odor nuisance, sand washers have been introduced; they reduce the content of organic compounds in the sand by washing (yan et al 2014). Sand with an organic content above 8% is transferred to specialized companies, while sand with an organic content below 8% can be reused, for example, it can supplement fine aggregate in the production of concrete mixture (Chen et al 2016).…”