Coagulation/flocculation as a pretreatment of landfill leachate for minimizing fouling in membrane processes

Abstract

a b s t r a c tSeveral works in the literature indicate that the combination of physical-chemical treatment (coagulation/flocculation) and membrane separation process can be a promising alternative for landfill leachate treatment. The objective of the present work was to evaluate the fouling potential in membranes after pretreatment of raw leachate by coagulation/flocculation process. Samples of stabilized leachate from Gericinó controlled landfill (Rio de Janeiro City, Brazil) were used. FeCl 3 and Al 2 (SO 4 ) 3 were applied as coagulating agents. The pH and coagulant dosage were evaluated. Modified fouling index (MFI) and silt density index (SDI) were used to estimate the formation of deposits in the nanofiltration (NF) or reverse osmosis (RO) membranes for leachate treatment. SDI was not significantly reduced despite the great removal of suspended matter by the pretreatment. The MFI of leachate pretreated with FeCl 3 was 100 times lower than the MFI of leachate pretreated with Al 2 (SO 4 ) 3 and about 10,000 times lower than the raw leachate. This can be attributed to the influence that the organic matter exerts on the MFI. Therefore, the results showed coagulation/flocculation would be a good pretreatment for NF or RO treatment of landfill leachate.

Evaluation of chemical oxygen demand and color removal from leachate using coagulation/flocculation combined with advanced oxidation process

“…This technology can remove contaminants through thermal decomposition and/or as a result of chemical reactions with free radicals produced inside cavitation bubbles, and it often leads to higher COD removal efficiency compared to other AOPs methods. [ 20 23 27 ] Furthermore, ultrasonic process does not require chemical reagents such as ozone and/or hydrogen peroxide and unlike other methods, it increases neither the turbidity nor the content of suspension in the effluent. [ 26 28 ] Cavitation is a phenomenon in which quick changes of pressure in a liquid lead to the formation of tiny vapor-filled cavities in places where the pressure is relatively low.…”

“…Coagulation and flocculation is considered a relatively simple physicochemical method in wastewater treatment that could be an appropriate pretreatment for other leachate treatment methods of municipal waste disposal sites. [ 4 27 ] Lan et al . argued that COD was effectively removed by 36% after pretreatment with potassium ferrate under optimal conditions.…”

Fouling Identification for Nanofiltration Membrane and the Potential Reduction of Pollutants in the Leachate by Using Fe/Al/PAC Coagulation

“…Coagulation/flocculation (C/F) and granular activated carbon (GAC) adsorption are the most frequently used pretreatment options to mitigate organic fouling and to improve quality of product water in the leachate treatment [13,14]. Coagulation [15,16] and sedimentation is one of the commonly used methods for treating leachate. Racar [17] concluded the optimization of coagulation with ferric chloride (FeCl 3 ) as a pretreatment for nanofiltration, performed to reduce membrane fouling and achieve higher permeate quality.…”