Wastewater generated in the Warsaw metropolitan area is neutralized at one of the most modern treatment plants in Poland.

The study discusses an experimental method for treatment of high strength domestic sewage on biofilters filled with polyurethane (PUR) waste in the form of trims of upholstery foam. We determined effectiveness of two biological preparations containing effective microorganisms in elimination of organic and biogenic compounds, indicator bacteria and total suspended solids from the sewage pretreated in a septic tank. After four months of work under a hydraulic loading of 76.4 mm∙d ^-1 we found the filter with 60 cm foam layer to be the most efficient in the elimination of BOD ₅, COD _Cr, NH ₄ ⁺-N and coliform bacteria. An average reduction in these pollutants reached 79.4%, 67.8%, 58.0% and 88.0%, respectively. Vertical filters filled with trims of upholstery foam and supplied with effective microorganisms ensured favorable conditions for development of heterotrophic and nitrifying bacteria without any need for additional aeration.

The impact of mechanical pre-treatment of municipal solid waste (MSW) on its biogas production potential was examined. Mechanical separation allowed the following size-fractions to be obtained: fine fraction - mineral fraction of municipal solid waste (MFMSW) (cf> < 20 mm), middle fraction - organic fraction of municipal solid waste (OFMSW) (20 mm< cf>< 80 mm), and coarse fraction (cf>> 80 mm). The most suitable fraction for biological treatment was OFMSW, containing about 76 % of high rate biodegradable organic fraction (HRBOF). The rate constant of degradation for organic compounds in OFMSW was 0.23 d·1• It was shown that total gas production (TGP) during 10 years may achieve 550 m3/Mg OFMSW. Mechanical pre-treatment may allow an 45 % decrease of the amount of landfilled MSW resulting in a reduction of greenhouse gas emissions of up to 70 m3/Mg over 10 years of landfilling (in contrast to MSW landfilling - 213 m3/Mg). The experimental results revealed that gas production potential should be determined on the basis of HRBOF content and measurements of the biogas production.