The leachate from incineration plant treating municipal solid waste (MSW) is a kind of wastewater

whose composition is very complicated and highly polluted

and after conventional biological treatment they can still not be directly discharged. According to characteristics of the biologically treated leachate

a combined process was proposed in which the biologically treated leachate was flocculated firstly by Ca(OH)2

and then the flocculated leachate was oxidized by ozone

and finally the ozonated leachate was filtered by NF membrane

and process mechanism was also explored. The experimental results indicated that Ca(OH)2 flocculation can effectively remove a large fraction of organic pollutants like heterocyclic compounds and improve the NF membrane flux. The permeate flux of flocculated effluent at the dosage of 8 g·L-1 Ca(OH)2 is increased by 8.2% compared with that of MBR effluent. The COD concentration in the flocculated leachate can be further reduced by the ozonation process

but NF membrane flux has no improvement. The reason could be that the siloxane compounds generated by the ozonation process caused the fouling of NF membrane. Compared with RO treatment process

ketones

amines

amides and heterocyclic compounds present in the biologically treated leachate can pass through the NF membrane. As a result

the NF permeate COD was increased by 100 mg·L-1 to 160 mg·L-1.Besides

the increases of NF average flux could lead to a slight increase of permeate COD. Membrane fouling is not obvious after the NF treatment of the biologically treated leachate and its pretreated samples.