Coagulation/flocculation of lignin aqueous solution in single stage mixing tank system: Modeling and optimization by response surface methodology

Abstract

Lignin particles contribute to color pollution in river water and treating this type of pollution biologically is difficult. In this study, the treatment of a model solution containing lignin using a single mixing tank system approach with poly-diallyldimethyl ammonium chloride (polyDADMAC) as destabiliser was carried out. The effect of various flocculants i.e. calcium lactate, magnesium hydroxide and anionic polyacrylamide (APAM) were investigated. Calcium lactate performed better than magnesium hydroxide and anionic polyacrylamide as flocculants. The coagulation/flocculation with polyDADMACcalcium lactate removed lignin through a complex mechanism: the adsorptive-charge neutralizationprecipitation-bridging mechanism. Response surface methodology (RSM) study indicated that strong interaction in the coagulation/flocculation of lignin occurred between the initial pH-polyDADMAC dosage, initial pH-calcium lactate dosage and polyDADMAC-calcium lactate dosage. The highest lignin removal achieved was between 50-68%. The removal behavior depended on the initial lignin concentration in the solution. The results showed that lignin removal from aqueous solution is possible in a single stage mixing tank by utilizing polyDADMAC-calcium lactate as a dual coagulant. The method mentioned here will potentially be useful for the treatment of lignin containing wastewater from several industrial processes such as palm oil mill, pulp and paper, olive mill etc.

Water Recovery of Black Liquor from Alkaline Pretreatment of Bioethanol Production from Oil Palm Empty Fruit Bunch by Coagulation and Flocculation Method

“…Reaction of ferrous sulphate in water in the presence of natural alkalinity [30], (6) The chemical reactions above (3)(4)(5)(6) are the hydrolysis reaction between coagulants followed by the formation of metal hydroxide floc as well as hydrogen ions. The hydrogen ion will react with alkalinity of the water and in the process, decreasing the pH of the water.…”

“…On the other hand, coagulation has an economic benefit due to its low capital cost, simple procedure and high efficiency [6]. The coagulation process decreases or neutralizes the negative charges of suspended solids which allows microfloc formation by van der Waals force [7], while flocculation helps the flocs interact with each other and form larger aggregates (macroflocs) [8].…”

PDADMAC as a flocculant for lignosulfonate of NSSC pulping process

“…In a previous study, 40% of lignin and 20% of hemicelluloses were removed from prehydrolysis liquor (PHL) by adding chitosan at the dosage of 2.2 and 1.5 mg/g, respectively . In a similar study, it was observed that up to 40% of lignin removal was achieved by adding 2.78 mg/L calcium lactate and 5.27 mg/L PDADMAC to a model alkali lignin (initial concentration of 50 mg/L) . As alkali lignin and lignosulfonate have very different characteristics, the results reported in previous studies may not predict the interaction of PDADMAC and lignosulfonate in the SL of NSSC process.…”

Optimization of Lignin Removal from Synthesized Wastewater by Iron (III) Trimesate

“…Generally, P&P wastewater treatment plants include physicochemical and biological processes to remove solids, suspended solids, colloids and dispersions. In a filtration system, membrane fouling results from lignin (Zahrim et al, 2015). However, the remaining pollutants may require tertiary treatment.…”