Combining CDOF and BAF for Advanced Landfill Leachate Treatment

In landfill leachate treatment systems, the concentrate produced in the membrane stage consists mainly of nanofiltration brine, reverse osmosis brine and mixtures of the two. Membrane rejection converts about 70%-80% of the feed into compliant clean water for discharge, while the rejected pollutants are concentrated in the remaining 20%-30% of the flow to form a high-strength by-product stream. Most landfills currently dispose of this concentrate by recirculation, which returns large quantities of salt to the treatment system, increases the load on ageing landfills and continuously shocks the biological units, ultimately degrading effluent quality and the overall operating efficiency of the site.

Recent studies show that advanced oxidation can convert the macromolecular and refractory substances in the concentrate into small molecules and short-chain compounds that micro-organisms can readily use, effectively improving biodegradability. Once the COD of the concentrate has fallen below 200 mg/L, the denitrification function of a DN-DC BAF (biological aerated filter) can remove ammonia nitrogen and total nitrogen efficiently, bringing the concentrate to discharge standard, optimising the upstream system and safeguarding stable operation of the landfill leachate plant.

SINOKLE has combined CDOF (an integrated ozone catalytic oxidation unit) with BAF to treat landfill leachate to discharge standard (Table 2 limits: COD < 100 mg/L, ammonia nitrogen < 25 mg/L, total nitrogen < 40 mg/L).

Concentrate: CDOF + BAF treatment process

Concentrate (NF + RO) treatment at a landfill site (capacity 50 t/d)

Water quality data

Treatment performance