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Organic Soils, i.e. Histosols. Soils: An Introduction (Singer and Munns). Non-agricultural Use of Soil. Using Soil as a Recycler. Solid Waste. Liquid Waste. Disposal/Treatment Options. Two options: On-site: Septic System Off-site: Sewage Trt Plants.
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Organic Soils, i.e. Histosols Soils: An Introduction (Singer and Munns)
Non-agricultural Use of Soil Using Soil as a Recycler
Disposal/Treatment Options Two options: On-site: Septic System Off-site: Sewage Trt Plants Soils: An Introduction (Singer and Munns) http://ga.water.usgs.gov/edu/wuww.html
Waste Water Treatment Plants(WWTP) • Combined OR • Separate sewage from runoff Soils: An Introduction (Singer and Munns)
WWTP Goals: • Clean water (effluent) to return to streams • remove excess nutrients • minimize pathogens • appropriate temperature • Sanitary solids disposal • landfill • incinerate • land application
Biosolids = solids after trtmt Soils: An Introduction (Singer and Munns)
Phosphorus (P): Crop Need vs Water Quality greenfacts.org Soil: crop production Water: eutrophication Goal: Satisfy P need, minimize P loss
Balance www.milorganite.com N:P ratio in these sources less than plant requires
Effects of Biosolids Treatment • Biosolids • concentrated with P • disposal=land application • Do biosolids differ in P availability as compared to manure or fertilizer?
P Removal Method: Lime • solids pumped to this tank • addition of lime • raise pH • reduce pathogens • precipitate P as Ca-P • (very insoluble) Baraboo, WI
P Removal Method: Fe or Al • add at influent entry • Fe • precipitate Fe-P • can become soluble in reducing conditions • Al • precipitate Al-P • too much Al can cause toxicity in soil • separate for solids Lodi (Al) Portage (Fe) WI
P Removal Method: Biological • primary influent trt • microorganisms “eat” dissolved P • solids removed by settling for further trt Madison, WI
Biosolids Trtmt Effects lime (Ca) Fe or Al biological P Removal Method
Field Study with plant real environment Incubations no plant controlled conditions Experimental Approaches
Biosolids History Incubation † PWEP=percent of TP that is water extractable
Soil Classification • Plano • Fine-silty, mixed, superactive, mesic Typic Argiudolls • Ringwood • Fine-loamy, mixed, superactive, mesic Typic Argiudolls Both soils are typical of MMSD land-application program
Effects on Bray P1 KH2PO4 † bars within a soil followed by the same letter are not statistically different at p=0.05
Effects on PBC PBC = P rate/∆STP
Predicting STP *, **, *** indicate statistical significance at p=0.05, 0.01, and 0.001, respectively
Effects on Bray P1 Arlington Field Experiment
Conclusions • P source treatment greatly influences P availability: • lime and biologically treated biosolids change BP1 similar to a typical dairy manure • Fe and Al treated biosolids have significantly greater PBC • P fertilizer has the smallest PBC • Field results follow same trends as Incubations • WEP of biosolids could be used to predict PBC
Implications • Is there a “best” method for P removal? • Does P removal method have implications for the functionality of biosolids for other purposes (besides keeping P from leaving in runoff)? • What do WWTP operates need to take into account when deciding on a P removal process? • How is soil being used as a recycler?
Green Waste • Reduce Reuse Recycle
Background:P Chemistry • Solubility in Soils - pH dependent Optimum P availability between pH 6-7. Brady and Weil, 1999
Effects on WEP KH2PO4