Coupling biofiltration process and electrocoagulation using magnesium-based anode for the treatment of landfill leachate

Abstract

In this research paper, a combination of biofiltration (BF) and electrocoagulation (EC) processes was used for the treatment of sanitary landfill leachate. Landfill leachate is often characterized by the presence of refractory organic compounds (BOD/COD < 0.13). BF process was used as secondary treatment to remove effectively ammonia nitrogen (N-NH4 removal of 94%), BOD (94% removed), turbidity (95% removed) and phosphorus (more than 98% removed). Subsequently, EC process using magnesium-based anode was used as tertiary treatment. The best performances of COD and color removal from landfill leachate were obtained by applying a current density of 10 mA/cm(2) through 30 min of treatment. The COD removal reached 53%, whereas 85% of color removal was recorded. It has been proved that the alkalinity had a negative effect on COD removal during EC treatment. COD removal efficiencies of 52%, 41% and 27% were recorded in the presence of 1.0, 2.0 and 3.0 g/L of sodium bicarbonate (NaHCO3), respectively. Hydroxide ions produced at the cathode electrode reacted with the bicarbonate ions to form carbonates. The presence of bicarbonates in solution hampered the increase in pH, so that the precipitation of magnesium hydroxides could not take place to effectively remove organic pollutants.

Novel and Conventional Technologies for Landfill Leachates Treatment: A Review

“…Oumar et al [169] introduced a combination of biofiltration (BF) (or trickling filters) and electro-coagulation (EC) processes for the treatment of sanitary landfill leachate (BOD/COD = 0.09). The biofilter system used a PVC column filled with indigenous microflora bacteria fixed on an organic support mainly comprised of peat and wood shavings.…”

“…A significant increase in the pH was recorded after the EC treatment. The pH passed from 8.4 before treatment to 10.6 after 30 min of treatment [169].…”

Removal of Pollutants in Different Landfill Leachate Treatment Processes on the Basis of Organic Matter Fractionation

“…Although water treatment technologies involving aerobic biological processes, such as membrane bioreactor (MBR; Ahmed and Lan, 2012), biofiltration (BF; Dia et al, 2016), and aerated lagoons (Mehmood et al, 2009), can handle a high concentration of ammonia (up to 1000 mg N-NH 3 L −1 ), they cannot meet the regulations on color and COD ). Numerous studies have investigated different physical and/or chemical posttreatment methods such as coagulation (Dia et al, 2016), electro-oxidation (EO; Zolfaghari et al, 2016b), nanofiltration (NF; Bohdziewicz et al, 2001), and adsorption (Liyan et al, 2009) for handling residual carbon (Renou et al, 2008), yet none of them proposed the best option for treatment.…”

“…The BF pilot consisted of a polyvinyl chloride (PVC) column with a height of 2 m and diameter of 0.2 m, filled by horizontal layers of wood and peat (Dia et al, 2016). Aeration was applied for the development of microorganisms on the surface of the media.…”

“…The anode was made of alloy-based magnesium, with a length of 80 cm and diameter of 1.9 cm; the cylindrical stainless steel cathode was 72 cm in length and 5 cm in inner diameter. The process run-up and other equipment were discussed in a previous study (Dia et al, 2016). As the conductivity of leachate was always >6 ms cm −1 for both chemical oxidation and ECo processes, addition of salt was not required.…”