Enhancing paper sludge dewatering by waste polyester fiber and FeCl3 for preparation of Fe-rich biochar

Abstract

The paper sludge conditioning effects of waste polyester textile fibers as skeleton builders combined with ferric chloride (FeCl3) were evaluated and the sludge dewatering mechanism was explored. The catalytic effect of Fe-rich sludge biochar (Fe-SB) on enhancing sludge dewaterability was evaluated. Results showed the combined fiber-FeCl3 conditioning significantly promoted the sludge dewaterability compared with conditioner alone, leading to a 77.5% decrease in specific filtration resistance and a 68.9% increase in net yield. The decrease of extracellular polymeric substances (EPS) contents showed that the EPS were difficult to extract and sludge floc strength was enhanced as a result of chemical reactions such as complexation processes and charge neutralization. Hence, the enhancement of sludge dewaterability was primarily due to the sludge cake with a porous and incompressible structure formed by fiber and FeCl3, and the rigidity structure of fiber. Moreover, the Fe-SB prepared by fiber-FeCl3 conditioning sludge could effectively activate persulfate to enhance the sludge dewaterability, with water content of dewatered sludge decreasing by 14.6%. The Fe-SB had dual functions of the heterogeneous catalyst of persulfate and skeleton builder. This study presents a sludge recycling method that combined physicochemical conditioning and sludge biochar materials prepared by pyrolysis.

Application of Advanced Oxidation Technology in Sludge Conditioning and Dewatering: A Critical Review

“…In addition, the SCOD first increased and then decreased with increasing temperature, that is, the dewatering performance of the sludge was closely related to the soluble organic matter it contained. At a pressure of 24 MPa and under a constant amount of oxygen, the degradation rates of TSS and VSS increased from 74% and 85% to 85% and 92%, respectively, with a temperature increase from 220 °C to 240 °C, indicating an increase the temperature, thereby reducing the concentration of total/volatile suspended solids in the sludge [ 62 ]. High temperatures can promote the degradation of suspended solid SS [ 63 ].…”