The results obtained during the first year of execution of a joint Russian-Dutch project “The development of integrated anaerobic-aerobic treatment of liquid manure streams with maximisation of production of valuable by-products (fertilisers, biogas) and re-utilisation of water” (1999–2001) are discussed. The application of a straw filter was an effective means to separate the solid and liquid fractions of diluted pig manure wastewater and resulted in the removal of a significant part of the dry matter, total nitrogen and phosphorus (65, 27 and 32%, respectively). From the filtrate generated, 60–80 % of the COD was removed in a UASB reactor operating at 20–30°C. Up to 66% of phosphate was precipitated after air stripping of the CO2 from the anaerobic effluents. Ammonia was efficiently removed (>99%) from the anaerobic effluents using zeolite (Ural laumantite) as an ion exchanger. However, the N-content of the resulting zeolite was too low to be used as a fertiliser. A feasible alternative for nitrogen elimination involved nitrification of the anaerobic effluent followed by denitrification in a UASB reactor using the COD of the filtrated manure wastewater as carbon source.
Pig farms in Leningradskij Oblast, Russia are usually large (/20,000 to 60,000 pigs per farm. As these farms discharge pig slurry into the adjacent rivers flowing into the Baltic Sea, there is a potential risk for pollution of both the rivers and the sea. This risk was assessed at the Vostochnii pig complex, which holds 60,000 pigs. The impact of slurry treatment on water quality in the groundwater (GW) and the river Igolinka, the recipient of the treated slurry, was investigated. The results indicated that untreated and treated slurry from pig farm wastewater treatment systems are potential point sources of environmental pollution. Generally, the GW was characterized by rather high contents of ammonium and chemical and biological demand for oxygen (COD, BOD). Similarly, the river exhibited high COD and BOD, contained considerable amounts of suspended substances and total P, and small quantities of NO 3 -N and NH 4 -N. Of the biological parameters investigated, the elevated population of fungi and pathogenic faecal bacteria Escherichia coli (100 Á10,000 CFU E. coli cells ml (1 ) determined in the river posed a potential health risk. Equally important was the marked total P load in the river, part of which could be transported to the Baltic Sea, where it could trigger eutrophication.
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