Study of Sludge Particles Formed during Coagulation of Synthetic and Municipal Wastewater for Increasing the Sludge Dewatering Efficiency

Abstract

Municipal wastewater sludge was produced by chemical coagulation of synthetic wastewater (sww) based on Synthene Scarlet P3GL disperse dye and real municipal wastewater (nww), coagulated by commercial coagulants PAX (prepolymerised aluminum coagulant) and PIX (a ferric coagulant based on Fe2(SO4)3). An attempt was made to correlate the sludge’s dewatering capacity (in terms of capillary suction time—CST) with operation parameters for wastewater treatment, size distribution and specific surface area of the sludge particles. It was found that the presence of phosphate ions in the system facilitates the removal efficiency of the above-mentioned dye (L) due to the interaction between the dye molecules and H2PO4− ions. Unlike sww, negatively charged organic substances (sorg) in nww are directly adsorbed on the surface of colloidal particles {Fe(OH)3} and {Al(OH)3} (prtc). It was also discovered that an increase in the dose of a coagulant led to an increase of CST for sww sludge and to a decrease of CST for nww sludge. It has been suggested that flocs composed of spherical {Al(OH)3} units possessed more internal space for water than aggregates consisting of rod-shaped {Fe(OH)3} units and, consequently, it is more difficult to remove water from Al-sww sludge than from Fe-sww. The results obtained showed that smaller particles dominate in sww sludge, while larger particles are prevalent in nww sludge. To explain this distinct difference in the size distribution of particles in sludge obtained with the use of Al3+ and Fe3+, simple models of aggregation and agglomeration-flocculation processes (aaf) of treated wastewater have been proposed. Except for PIX in nww, the analyzed particles of the investigated types of sludge were characterized by similar specific surface area (Sps), regardless of the kind of sludge or the applied coagulant. Slightly larger, negatively-charged sorg bridges, anchored directly on the surface of positive prtc are more effective in closing the structure of nww sludge than small L bridges of the dye molecules anchored on the surface of prtc via H2PO4−. All the discovered aspects could lead to improved performance of wastewater treatment plants (WWTP) by increasing the efficiency of sludge dewatering.

Dehydration Performance of Municipal Sludge and Its Dewatering Conditioning Methods: A Review

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A Novel Natural Active Coagulant Agent Extracted from the Sugarcane Bagasse for Wastewater Treatment

“…In a comparison of the polysaccharide content and coagulation performance, higher polysaccharide content or active coagulant agent in natural coagulant will result in lower coagulant dosage required for optimum turbidity removal [54]. A higher coagulant dosage is undesirable as it will not only increase the cost but also can produce more sludge [55].…”

Kajian Awal Produksi Fero Sulfat dari Slag Nikel Melalui Proses Pelindian Menggunakan Asam Sulfat

“…Partikel Fe(OH)3 yang terbentuk selama proses reduksi akan bertindak mendestabilkan partikel koloid di dalam air limbah dan sebagai adsorben di dalam proses agregasi dan aglomerasi polutan yang ada di dalam air limbah (Smoczynski et al, 2019).…”