Implications of Heavy Metals in Sewage Sludge Where Do We Stand on Regulations?

Regulation? Why? - Authorization or mandate How? - Concepts, goals, assumptions, and approaches What? –Contents –Implement-able package

Regulate? Not Regulate? Opponent –Potentially hazardous substances are present –Assuming practice will be harmful until proven safe –Ban or strict limitation Advocate –Practiced for a long time without “documented” harmful effects –Assuming practice is safe until proven otherwise –Promotion, no need to regulate, or general guidelines Framework of mind –Decision of regulate may be different

Cumulative Loading

Annual Loading

Discrepancies, Why? Rule making process –Mandates –Concepts –Goals –Assumptions –Approaches

Rule Making Process Objective –goals regulation must accomplish Assumptions –domain within which proposed rules apply Approach –strategy to accomplish objective Final rule –Reasonable? –Implement-able? Acceptance? Public, stakeholders

Approaches Ecological Balance –Prevent pollutant accumulation in soils Capacity utilization –Maximize pollutant attenuation capacity of soils

Prevent Pollutant Accumulation Assumptions Soil - foundation of terrestrial ecosystem and irreplaceable natural resource Use without undue restrictions, if soil is free of pollutants Experience increasing difficulty to support uses, if pollutants are allowed to accumulate Unknown ecological consequences

Prevent Pollutant Accumulation Goal No pollutant accumulation in the sewage sludge-receiving soils

Prevent Pollutant Accumulation Regulatory Approach Pollutant-free sewage sludge Pollutant input = Pollutant output

Prevent Pollutant Accumulation Advantages In agreement with ecology - sustainable practice Numerical limits - obtain from simple mass balance calculations Detailed knowledge on fate and transport of pollutants not needed One set of standards fits all situations Easy to implement

Prevent Pollutant Accumulation Disadvantages Require rigorous pretreatment for wastewater discharge Phase out incompatible industrial raw material and household products Performance and reliability of wastewater treatment processes Little agronomic benefit

Maximize Attenuation Capacity Assumptions Soil assimilates, attenuates, and detoxifies pollutants Capacity should be utilized - realize benefits of resource conservation Land application, environmentally, is equal if not a better option Stringent limits discourage resource conservation and recovery

Maximize Attenuation Capacity Goal Realize agronomic benefits of applying sludge on land Keep pollutants in the soil at a safe level - public health and environment Beneficial use without compromising public health and environment

Maximize Attenuation Capacity Regulatory Approach Identify safe/unsafe sludge for land application Determine maximum tolerable pollutant input Set maximum tolerable pollutant levels in soil or products

Maximize Attenuation Capacity Advantages Resource conservation - appreciation of agronomic benefits Flexibility of developing safe and site- specific land application operations Cost effective - competitive with other options

Maximize Attenuation Capacity Disadvantages I Upper limits for each pollutant must be evaluated separately Technical information is not always available - uncertainties in setting numerical limits Pollutant levels in receiving soil will increase - under long-term use and high rates

Maximize Attenuation Capacity Disadvantages II Margin of safety “may be” narrower Site may require long-term monitoring

U.S. vs Europe U.S. - maximizing pollutant attenuation capacity of soils European countries - preventing pollutant accumulation in soils

Will Sludge Ever Be Free of Metals? Not likely Metals will always be used in industrial processing and consumer goods They will find their ways into the wastewater collection systems Source control is essential

Heavy Metals in Sewage Sludge Trends Metal concentration of sludge continued to decrease - implementation of industrial waste pre-treatment program Pollutant input decreases when “agronomic rate” is followed

USEPA Sewage Sludge Survey

AMSA Sewage Sludge Survey

Estimated Pollutant Inputs (1000 t ha -1 ) Reasonable application: <10 t ha -1 y -1 for <100 y, therefore <1000t ha -1 Use Sewage Sludge from San Jose as an example Estimated pollutant inputs are considerably less than pollutant loading rates specified in Part 503 regulation

San Jose Sewage Sludge

Implementation No rule is and will be perfect Fulfill its mandate and accomplish its goals If not implementable, regulation = no regulation Regulations are better than no regulation Technological issues Costs issues

Possible Approaches Match benefits –Waste disposal –Plant nutrients Sharing and distribution of cost and risk Urban-rural alliance –Special district –Cooperative –Collective planning and implementation Long-lasting institutional entities