Coagulation–flocculation studies of tannery wastewater using cationic polymers as a replacement of metal salts

Abstract

Studies were conducted to evaluate the efficiency of cationic polymers as a suitable replacement of metal salts for the treatment of a local tannery wastewater. Eleven cationic polymers of varying molecular weights (MW) and charge densities (CD) were examined using jar test apparatus. Three cationic polymers: one with MW of 4 million Dalton and CD of 55%; second with MW of 6 million Dalton and CD of 40%; and the third with MW of 8 million Dalton and CD of 40% were found suitable for tannery wastewater treatment at an optimum dose of 20 mg/L for each. Percentage removals with these three cationic polymers for turbidity, total suspended solids (TSS), total chemical oxygen demand (TCOD) and chromium lied in a range of 91-95%, 69-83%, 25-29% and 96-97%, respectively with respect to plain settled wastewater. The cost of the most suitable cationic polymer C-496 at its optimum dose was $0.09 per cubic metre of wastewater and sludge production was 35 mL/L. The results demonstrated that treatment of tannery wastewater with cationic polymers is a viable and economical option when compared with metal salts.

Coagulation–flocculation studies of tannery wastewater using combination of alum with cationic and anionic polymers

“…All these polymer were in dry form. In order to select a fixed dose of cationic polymer, the studies conducted by Haydar and Aziz [15] were used as a guideline. In these studies the treatment of tannery wastewater was carried out using cationic polymers alone, without any metal salts.…”

Synthesis and characterization of kaolinite coated with copper oxide and its effect on the removal of aqueous Lead(II) ions

“…The coagulation-flocculation-sedimentation method is widely used owing to its simplicity and low cost (Rivas et al 2004;Ndabigengesere and Narasiah 2010). However, this method will generate a large volume of sludge with low density that requires further dewatering and disposal (Haydar and Aziz 2009). The technology using membrane provides high efficiency.…”

“…However, this technology has some setbacks, inclusive difficulty in maintenance. The drawback of ion exchange is the interfering of competing ions and renewal (Haydar and Aziz 2009;Hom et al 1982).…”

Optimization of sequencing batch reactor for wastewater treatment using chemically enhanced primary treatment as a pre-treatment

“…Apart from biological wastewater treatment, another enhanced pollutant removal process exists, particularly at the primary level of wastewater treatment, termed chemically enhanced primary treatment (CEPT). Usually, metal salts or polymers are used in CEPT(Haydar and Aziz, 2009a;Haydar and Aziz, 2009b;Haydar and Aziz, 2009c;Johnson et al, 2008;Mahmoud, 2009;Mikelonis. 2008;Sarparastzadeh et al, 2007;Song et al, 2004).…”