Wastewater Polishing and Water Reuse

2 Treatment of Leachates from Landfills and Composting Plants 

Reverse osmosis is used full scale for the treatment of landfill leachates (Linde et al., 1995). The RO retentate can be recycled to the landfill either directly or after evaporation. If this is not allowed, as is the case in Germany, more expensive solutions are to be found for the concentrate (Melin et al., 2005). A possible treatment method is activated carbon adsorption/oxidation, patented as Biomembrat-Plus, or even the combination of high-pressure RO, a crystallizer, and NF (Melin et al., 2005). 

Another combination that was suggested (Melin et al., 2005) is the use of biology and NF, extended with powdered activated carbon (PAC) adsorption. 

Similar to the application of NF for textile effluents, the operating temperatures in the pulp and paper industry are high—ideally, NF should operate at 70°C and withstand sudden increases up to 90°C (Nystrom et al., 2005). In some cases, very alkaline conditions occur as well. Another similarity with textile effluents is the occurrence of (bio)fouling when easily degradable components (lignins, polysaccharides) are present (Nystrom et al., 2005). 

Given the huge volumes of water used in the pulp and paper industry, it is surprising how few existing mills incorporate NF. Nystrom et al. (2005) give an overview of industrial plants and pilot-scale plants. From these experiences, it is clear that the permeate quality 

---