Manure processing to reusable water using constructed wetlands Meers E. , Michels E. , March 8, 2011
Presentation outline I. General introduction manure excesses & manure treatment II. Treatment to dischargeable water using constructed wetlands as a tertiairy step II. Project overview re-use of treated effluents as secondary water resource
I. General Introduction
The Flanders situation Manure excess on soil balance Intensive industrial farming Exceedance over EU localized directive results in Nitrate nutrient (N, P) % in 2003 -2004 excesses at a regional level. % in 2004 -2005 % in 2005 -2006 Similar situations in US (NC), France (Bretagne), Netherlands, Germany (Nord Westfalen), Italy,
Manure processing Animal manure Solid fraction Physical separation Soil enhancer Composting Liquid fraction Fertilizer Nutrient reduction by biological treatment Spreading over land
Manure processing Animal manure Solid fraction Physical separation Soil enhancer Composting Liquid fraction Fertilizer Spreading over land Dischargeable water Nutrient reduction by biological treatment Constructed wetlands
Constructed wetlands Cascade of plant- & microbial based processes
Constructed wetlands Rich diversity of plant species and substrates
Constructed wetlands “Intelligent design”: control in function of crucial monitoring parameters, feed forward & feedback loops
Cost per m 3 ‣ Constructed wetlands were designed as an alternative for spreading manure ‧ Surface: – In general: 1 m² / 1 m³ manure per year (~ 1 ha for 10. 000 pigs) – In practice: > 1 m² / 1 m³ manure ‧ Cost (current systems): – 3, 5 -4, 5 €/m³ (incl. operational and investment cost, period 10 year) – After depreciation (10 years): 2, 5 -3, 0 €/m³ ‧ Various additional break-throughs pending with impact on : capacity (m 3/m 2. j) and hence cost per m 3
II. Treatment to dischargeable water
Constructed wetlands Liquid fraction after biology Effluent Constructed Wetlands 300 mg/l total nitrogen < 15 mg/l total nitrogen 250 mg/l total phosphor < 2 mg/l totaal phosphor 3000 mg/l COD < 125 mg/l COD
Constructed wetlands VLAREM standard environmental quality standard N content
III. Project overview: water re-use
Water scarcity & water re-use Animal manure ‣ sufficient water supply is one of the most important environmental and economical challenges in agriculture in the near future Physical separation Liquid fraction ‣ use of purified water on the farm is scarce ‣ is reuse of end effluent of constructed wetlands an option? Dischargeable water Nutrient reduction by biological treatment Constructed wetlands
Project § 5 different CW locations, monthly sampling § physico-chemical parameters (non-limitative list) SS Ntot Mg Cd Co EC NO 2 K Cu Cr p. H NO 3 Na Fe Ptot NH 4 F Mn ortho-P BOD Cl Ni NTU COD SO 4 Pb hardness Ca Al Zn § bacteriological parameters C. perfringens Salmonella colony count (22°C) Enterococci E. coli spores sulfite red. Clostridia § reuse options (high & low grade) drinking water live stock irrigation cleaning water cooling water total Coliforms colony count (37°C)
GI – 3 ha ICH – 0, 5 ha Wetland area Prim. & Sec. Manure treatment Pig farm PI – 1 ha WVL– 3 ha LA – 0, 5 ha
Results- compared to pig drinking water § Overall excellent results § Problem parameters § Location Ex. Other spore elements: mainly below DL
Total nitrogen § VLAREM (15 mg/l) Ntot mg/l § No criteria for drinking or irrigation water Location
Nitrate § Drinking water (taste) pig: 100 mg/l NO 3 mg/l Ntot mg/l § ≠appl. Irrigation, process-, cooling- & cleaning water : algal bloom, leaching Location
Total phosphorus § VLAREM (2 mg/l) § No criterium for drinking water P (mg/l) essential element, non toxic, eutrofication pipes § Intensive agri- & horticulture: 15 mg/l algal bloom storage § Process-, cooling- & cleaning water: Location eutrofication
Total colony count (37°C) Cfu/ml Criterium drinking water pig: 100. 000 cfu/ml Time
Hardness § Drinking water pig: 20 D°H Hardness (D°H) § ≠appl. irrigation 21, 5 D°H Risk clogging § Cool- & cleaning water salt deposit upon heating, ex. cooling greenhouse Location
Iron content § Variability in location Fe (mg/l) § Drinking water pig: 0, 5 mg/l taste, smell, clogging § Irrigation: 0, 5 -15 mg/l +: grassland, vegetables, green house farming, cultivation trees -: open-air culture, intensive agri& horticulture, substrate culture Rust deposit § Ground water in Western Flanders: up to 4 mg/l Location §Iron removal necessary -:
Spores sulfite reducing Clostridia Cfu / 100 ml Criterium drinking water pig: 0 cfu/ 100 ml Time
Conclusions ‣ preliminary results indicate that effluent quality scores better than initially anticipated, both for the bacteriological as well as the physicochemical parameters. ‣ even for high grade applications constraints for reuse were limited to parameters which are easy to address using simple polishing steps. ‣ we expect that reuse of constructed wetland effluent in various applications will have important economical and environmental benefits.
On site polishing
Future perspectives Biomass for energy Algae production Biodiversity Aquaculture
Contact Prof. dr. ir. Erik Meers (e-mail): erik. meers@UGent. be ‣ even for high grade applications constraints for reuse were limited to parameters which are easy to address dr. ir. Evi Michels using simple polishing steps. (e-mail): evi. michels@UGent. be ‣ we expect that reuse of constructed wetland effluent in various applications will have important economical and environmental benefits.
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