Treatment of landfill leachates by comparing advanced oxidation and coagulation-flocculation processes coupled with activated carbon adsorption

Abstract

This work compares two pre-treatments (coagulation-flocculation process (CF) and the Fenton oxidation Method (FE)) of the activated carbon adsorption process (AC) to optimize the removal of the organic compounds in landfill leachates. The content of organic compounds was measured in terms of three global parameters: colour, chemical oxygen demand (COD) and dissolved organic carbon (DOC). The result obtained in discontinuous reactor conditions showed an increase in colour removal from 1.5 to 2.0 times and a decrease of COD between 0.3 to 0.5 times for the FE-AC treatment, in relation to the CF-AC treatment. On the other hand, the data obtained in continuous reactor conditions (packed columns) showed that the column fed with leachate CF exhibited operation times 1.3 times longer and a better physiochemical quality in the filtrate (COD and colour) than the one fed with the FE leachate. Nevertheless, the adsorption capacities in the colour removal column of COD and DOC were higher for the FE leachate.

A comparative study on the efficiency of ozonation and coagulation–flocculation as pretreatment to activated carbon adsorption of biologically stabilized landfill leachate

“…This can be explained by the production of smaller and more easily adsorbable compounds during ozonation. The small size of the ozonation products increases their surface area for adsorption and their accessibility to the GAC micropores (Ramirez Zamora et al, 2000). In contrast, coagulation-flocculation is only efficient in removing humic acids, whereas fulvic acids remain in the leachate still reducing the adsorption capacity of GAC.…”

“…GAC adsorption is thus more efficient in reducing a 254 from leachate pretreated with coagulation-flocculation than with ozonation. Though ozonation of bulk organic matter leads to the production of smaller compounds which are easily adsorbed (Ramirez Zamora et al, 2000), the by-products from oxidation of aromatic sites and carbon to carbon double bonds are very hydrophilic thus poorly adsorbed by GAC. On the contrary, infra red analysis of the chemical composition of the coagulated effluent reveals the presence of amines and aliphatic compounds (Monje-Ramirez and Orta de Velásquez, 2004).…”

“…For instance (Kurniawan et al, 2006b) uses column studies to demonstrate a 4 times improvement in breakthrough time of COD from GAC, when ozonated leachate is treated using ozone modified GAC. To compare the effect of different types of treatment on the operation time of an activated carbon bed, (Ramirez Zamora et al, 2000) utilized coagulation-flocculation and Fenton oxidation as pre-treatment steps before fixed bed activated carbon adsorption. Results showed that the operation time of the activated column fed with coagulation-flocculation effluent was extended by a factor of 1.3 compared to the column fed with Fenton oxidation effluent.…”

Coagulation-Flocculation and Air Stripping as a Pretreatment of Young Landfill Leachate~!2010-02-12~!2010-03-24~!2010-05-11~!

“…The characterization of leachate is given in Table 1. It is observed that presenting a relatively high value of COD and BOD 5 and the rate of COD/BOD 5 values indicates that the leachate can be defined as young. There has beeen low COD and BOD 5 concentrations according to the samples taken between January and December in 2006 depending on the monthly rainfall.…”

“…Young leachate is characterized by chemical oxygen demand (COD) concentration higher than 5 g/L and by low nitrogen concentration (<400 mg/L of N). Old leachate is characterized by a high nitrogen concentration (>400 mg/L of N), high content of recalcitrant compounds and low biodegradable organic fraction (BOD 5 / COD 0.1) [4,5].…”