Biosolids versus other Plant Nutrient Sources: A Cursory Comparison of Benefits and Risks

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1 Biosolids versus other Plant Nutrient Sources: A Cursory Comparison of Benefits and Risks New England Residuals and Biosolids Conference November 15, 2006 Presented by Andrew Carpenter Northern Tilth

2 The Wastewater Treatment Process and Manure Collection on Farms Each person generates approximately 47 dry lbs/year of sludge (dry weight basis): 50,000 dry tons/year in northern New England (equivalent of 200,000 wet tons at 25% solids) Treatment to kill pathogens, and demonstration of chemical quality Biosolids A farm with 200 animal units (milking approximately 100 cows) generates approximately 3400 wet tons of manure per year Typically stored in lagoons for up to six months and directly land applied without pathogen treatment

3 Biosolids and Manure Volumes in Maine Wet tons generated annually Disposed Recycled 0 Biosolids Animal Manure Approximately 128,000 tons of sewage sludge was generated in Maine in 2004

4 Organic Matter Transformations in Soil Organic N Organic C (energy source) C assimilation Microbial attack N Mineralization N assimilation NO 3 - Plant-available nitrogen in a slowrelease form Mature Soil Organic Matter (Soil Humus) Improving soil fertility through the addition of organic matterbased residuals is a primary tenet of sustainable agriculture Healthy soil ecosystem Long-term pool of soil nutrients Reduced erosion Feeding soil not just crops

5 Benefits of Organic Matter-Based Soil Amendments to Soil Fertility Nutrient source Slow-release nitrogen and phosphorous Potassium in the case of manures Organic matter water-holding capacity soil aggregation (erosion resistance) long term pool of plant nutrients Lime replacement (lime stabilized biosolids) Source of micro-elements

6 Nitrogen Fertilizer and Energy Use 78,000 wet tons of biosolids recycled in Maine x 25% solids content 19,500 dry tons of biosolids 19,500 dry tons x 2000 lbs/ton x 4.46% nitrogen 1,739,400 lbs of nitrogen recycled to soils 0.22 gallons of fuel oil used to produce and package each pound of nitrogen fertilizer 382,668 gallons of oil saved by recycling biosolids, just looking at nitrogen fertilizer replacement The value of lime stabilized biosolids in Maine, based on fertilizer replacement value was estimated to be $45.32 per dry ton in This value is likely higher today due to increased production costs of fertilizers Energy costs of nitrogen production adapted from Energy and alternatives for fertilizer and pesticide use. Z.R. Helsel 1992

7 Some Facts I ve Heard About Biosolids Sludge is not even a good fertilizer After rain, all the land-applied sludge runs off into rivers and streams. Sludge spreading spreads disease. Maine has some of the weakest sludge laws in the country

8 Sludge is not even a good fertilizer Nutrient Content of Manure and Biosolids Nitrogen Phosphorous Biosolids Dairy Manure Poultry Manure Potassium % dry wt. basis Biosolids values from The Use of Biosolids in Maine: A Review (report by the Mitchell Center) Manure Values calculated using median values from the 2005 University of Maine Analytical Lab manure analysis summary report

9 After rain, all the land-applied sludge runs off into rivers and streams Setbacks and Testing Requirements for Biosolids and Manure in Maine Feature Private well Swales Surface Water (8-15% slopes in buffer) Surface Water (>15% slopes in buffer) Nutrient Testing Frequency (4000 wet ton per year example) Class B Biosolids Chapter 419 Regulations Application not allowed Four times per year Manure NMP Guidance Document 100 Avoid swales (no setback) >100 (take site-specific factors into account) Once every five years* * This is a requirement of Maine s Nutrient Management Law, and applies to all NMPs, regardless of the size of the farm

10 Sludge spreading spreads disease. Pathogens in Biosolids and Manures Soil Amendment Class B Digested Class A Composted Biosolids Dairy Manure Poultry Manure Fecal Coliform (MPN/g) 104, ,000,000 5,000,000 Biosolids data from Lue-Hing et al Manure data from ASAE 2000

11 Maine has some of the weakest sludge laws in the country most stringent Maine v. Federal Biosolids Regulations Regulation DEP Chapter 419 US EPA Part 503 Trace Metal Standards Dioxin Standard VOCs, SVOCs, pesticides and PCBs Surface Water Setbacks Class A Biosolids Program License Lower maximum concentrations than 503 for all trace metals 1 st risk-based standard in the country for dioxin in biosolids Screening analysis required As shown previously Required Risk-based concentrations No standard, no testing required No standards, no testing required 10 meters from surface water No requirement for license

12 Soil Amendment Trace Metal Concentrations Metal Maine Biosolids a Dairy Manure b Poultry Manure c Phosphorous Fertilizer c Arsenic Cadmium Chromium NT 173 Copper * Lead Mercury NT 0.1 Molybdenum NT Nickel Selenium NT NT Zinc a - Biosolids values from The Use of Biosolids in Maine: A Review (report by the Mitchell Center) b- from McBride and Spiers 2001 c from Moss, Epstein an d Logan, 2002

13 Biosolids as a Soil Vitamin Maine Biosolids Rite-Aid Centra Vit Chromium Copper Molybdenum Nickel Selenium Zinc

14 Dioxin Levels in Various Environmental Media Source Concentration (ppt TEQ dry weight) Maine Biosolids Average (31 samples ) 6.3 Maine Biosolids Regulatory Limit 27 U.S. soils average (rural) EPA data 4 U.S. soils average (urban) EPA data 19 Leaf and yard waste composts (range of 2 9 samples) 5-91 Cow Manure (6 samples from 2003 European study ) 3.6 Times Beach, Missouri Up to 340,000

15 Biosolids and Manure Volumes in Maine Wet tons generated annually 5 Maine DEP Representatives in charge of compliance (biosolids is not their only area of oversight) Disposed Recycled 0 Biosolids Animal Manure Approximately 128,000 tons of sewage sludge was generated in Maine in Department of Agriculture Compliance Officers

16 Biosolids Recycling Rates 100% 90% 80% This is an environmental success story 70% 60% 50% 40% 30% Maine New England National Average 20% 10% 0% Percent Sewage Sludge Recycled as Biosolids The amount of sewage sludge generated in the U.S will continue to increase as water quality standards are strengthened

17 Conventional v. Organic Agriculture: One study Results from a recent peer-reviewed article from the Journal of the Science of Food and Agriculture, Does organic farming reduce the content of Cd and certain other trace metals in plant foods? A pilot study (Jorhem and Slanina, 2000) The results [of the study] indicate that organic farming, at least in the short term, does not necessarily result in reduced levels of Cd and other potentially harmful metals in foods of vegetable origin Cadmium concentrations were significantly higher in the conventional system in one set of farm comparisons, and significantly lower in the other set of farm comparisons

18 Pretreatment and Regulatory Controls Reduced Cd in PA Biosolids (Stehouwer) ) Cadmium Median r 2 = th Percentile Error bars range from 25 th to 75 th percentile Cd concentration ( Slide provided by Dr. Rufus Chaney, USDA Year PSU data only

19 Bunker Hill, Idaho -- Smelter killed ecosystem Superfund Site. Slide provided by Dr. Rufus Chaney, USDA

20 Highly Zn-phytotoxic smelter and mine waste contaminated soils at Bunker Hill, ID; Slide provided by Dr. Rufus Chaney, USDA Background = Biosolids+Wood-Ash Remediated Foreground = Seeded control hazardous soil.

21 Summary Maine biosolids represent a valuable resource for improving soil fertility in a sustainable manner and help to reduce the need for using chemical fertilizers All agricultural nutrient sources need to be used according to practices that maximize the efficiency of uptake of nutrients by plants and minimize the risks for those nutrients and other potential contaminants to negatively impact soil and water quality Oversight of the application of nutrient sources to agricultural land is currently based more on public perception issues than on actual environmental risks Maine s biosolids recycling rate is well above the national average, and is a source of pride for Maine wastewater treatment professionals Recycling biosolids as soil amendments in Maine represents negligible risks to human health and the environment