Verwerking van mest tot loosbaar/herbruilbaar water

1. Verwerking van mest tot loosbaar/herbruilbaar water • Evi Michels 1,2, Erik Meers 1,2, Filip M.G. Tack 1 • 1 Laboratorium Analytische Chemie en Toegepaste Ecochemie, Universiteit Gent, Coupure Links 653, 9000 Gent – België • 2 Innova Manure, Kriekenstraat 66, 8480 Ichtegem, België • Contact: Evi.Michels@Ugent.be; Erik.Meers@UGent.be • Introduction • Toenemende intensifiëring van de landbouw en inkrimpende landbouwarealen confronteren geïndustrialiseerde regio’s wereldwijd worden geconfronteerd met lokale overproductie van dierlijke mest. Ook Vlaanderen heeft momenteel te kampen met aanzienlijke mestoverschotten, die verwerking vereisen op een economisch aantrekkelijke manier. • In voorgaand onderzoek konden we aantonen dat constructed wetlands een effeciënte manier vormen om varkensmest na biologie verder op te zuiveren tot een loosbaar effluent dat voldoet aan de wettelijke Vlarem normen (concentr aties lager dan 15 mg N/l, 2 mg P/l and 125 mg COD/l). • Currently, ground water and tap water are the predominant water sources in agriculture. However, these types of water become more and more scarce and expensive. To date, purified agricultural wastewater is hardly used in agriculture. It can therefore be expected that sufficient water supply will become an important (technical and economical) challenge in the near future. • Reuse of effluents from manure processing is an intriguing option . However, thorough research is required to explore the possibilities for high grade (live stock drinking water, irrigation water) and low grade (cooling water, cleaning) applications. Manure processing • Experimental set-up & Results • Effluent from 5 different constructed wetlands were monitored on a monthly basis and analysed on a broad range of physicochemical and bacteriological parameters. • Physicochemical parameters include pH, salts, trace elements, exchangeable bases, nitrogen compounds, BOD, COD, phosphate,… • Bacteriological analyses comprise colony count at 22°C and 37°C, Salmonella spp., C. perfringens, total coliforms, E. coli, Enterococci and sulphite reducing Clostridia. • Even for high grade applications such as drinking water for livestock const Manure seperation Liquid fraction Solid fraction nutrient reduction by biological treatment conversion into a soil enhancer constructed wetlands spreading over land total phosphor nitrite total nitrogen • Constructed wetlands • The wetland is designed in a multi-bed system, including a cascade of horizontal and vertical helophyte filters as well as hydrophyte and pleustophyte lagoons. • To our knowledge this is the first successful full-scale application of constructed wetland technology to convert manure into water of sufficient quality. improvement of water quality throughout the different bassins in the constructed wetland air view of a constructed wetland under construction • Conclusions • Preliminary results indicate that effluent quality scores better than initially anticipated, both for the bacteriological as well as the physicochemical parameters. The stringent discharge criteria were consistently met, as was expected, but other test variables determining the re-use potential of the effluents also exhibited positive results. • Even for high grade applications such as drinking water for livestock constraints for reuse were limited to parameters (e.g. iron content, water hardness and certain salts) which are easy to address using simple polishing steps. • We are hopeful that reuse of end effluent from constructed wetlands will be technically and economically feasible. As water sources become more and more scarce and expensive, we expect that reuse of constructed wetland effluent in various applications will have important economical and environmental benefits.