RISK TO HEALTH FROM THE LAND APPLICATION

OF SLUDGE

Dr. Joseph B. Farrell, Consultant1117 Stormy Way Cincinnati, Ohio

45230Phone/Fax: 513-231-7451

FARRELLJ44UND@AOL.COM

Required Reading

• “Biosolids applied to Land: Advancing Standards and Practices”. 2002. Prepared by Committee on Toxicants and Pathogens in BIosolids Applied to Land, National Research Council, Pub. National Academy Press, Wash., D.C.

• Smith, J.E., Jr. et al. 2005. “Infectious Disease Agents in Sewage Sludge and Manure.” Pub. The JG Press, Emmaus, PA.

NRC Committee Chairman’s Comment on LA Report

• “The Science of Recycling Sewage Sludge” by Thomas A. Burke. 2002. Buckeye Bulletin, p. 34, November,

Burke’s comment on the NAS report, “We found no evidence of an urgent public health risk from exposure to land-applied biosolids, based on our review of the scientific literature.”

NRC Report’s Top Recommendations

• Use improved risk-assessment methods

• Conduct new survey of chemicals and pathogens in sludge.

• Implement human health investigations.

• Increase EPA resources for biosolids

Makeup of Raw Sewage Sludge

• Paper

• Fecal matter

• Kitchen wastes

• Bacterial mass from WW treatment

• Gray water residues

• Solids in street runoff

• Industrial wastes

Chemical Makeup of Sewage Sludge

• Bulk organics (carbohydrate, protein, fat, mineral oil)

• Trace organics (hormones, plasticizers, dioxins, PCBs)

• Nitrogen-phosphorus-potassium

• Industry (insoluble or absorbed inorganic or organic chemicals)

What Substances are Health Risks?

• Inorganic chemicals (heavy metals) – cumulative.

• Trace organics (dioxins, PCBs) – cumulative

• Pathogens (viruses, bacteria, parasites) – immediate

• Dead bacteria (gram-negative bacteria cell walls) - immediate

Quantifying The Risk By Risk Assessment: Concentrations and

dose/response must be known

Concentration Dose/response

Metals yes yes

Toxic organics Yes Much knowledge

Pathogens, dead bacteria

No Great variations

BASIS OF RULE

• Risk-based for chemical contaminants (heavy metals, organic chemicals)

• Based on best judgment for pathogens

Pathways of Toxicants and Pathogens in Biosolids to Man

Land Application of Biosolids:

Exposure Route

Surface Water

Ingestion

Surface Water

Ingestion

Ground Water

Ingestion

Ground Water

Ingestion

Direct Soil

Ingestion

Direct Soil

Ingestion

Plant Ingestion

Plant Ingestion

InhalationInhalation

Host/Pathogen Interaction: Disease

Transmission

Why no Risk Assessment for Pathogens?

• Pathogen densities are not conserved

• Die-off rates are not well-quantified

• Infectious dose vary widely

• (But, we know enough to establish reasonable controls)

Dose/Response for Pathogens

Organism Infective Dose

Protozoa 1-50 cysts

Enteroviruses 1-50 PFU

Helminths One egg

Pathogenic bacteria 100-1,000,000

CFU

Bacterial Pathogens of Potential

Concern in Biosolids

Major Concern • Salmonella• Shigella• enteropathogenic E. coli• Yersinia enterocolitica• Campylobacter jejuni• Vibrio cholera• Leptospira• Fecal coliform

New issues • E. coli 0157:H7• Listeria• Helicobacter• Mycobacteria• Aeromonas • Legionella• Burkholderia• Endotoxins• Antibiotic resistance

Human Enteric Viruses (from Gerba)

Virus Group No. of Types

Enterovirus (polio, coxsackie, echo)

69

Hepatitis A virus 1

Reoviruses 3

Rotaviruses 8

Adenoviruses 49

Astroviruses 7

Hepatitis E virus 1

Caliciviurses 3?

Major Helminths/Protozoa in Sludge

ProtozoaCryptosporidium spp.Giardia spp.

HelminthsAscaris spp.Toxocara spp.Trichuris spp.Taenia

Diseases of Special Concern

• SARS: It is not enteric. It has almost disappeared (but could come back). It is spread by inhalation of large suspended droplets.

• Prion Diseases: Consumption of contaminated meat by animals or man. Resist thermal treatment but perhaps not biological digestion. Keep it out of sewers. (CWD, BSE, vCJ disease). CWD does not cross species barrier.

Survival Times of Pathogenson Soils and Plants

SOIL PLANTS

PATHOGEN

ABSOLUTE MAXIMUM

COMMON MAXIMUM

ABSOLUTE MAXIMUM

COMMON MAXIMUM

Bacteria 1 year 2 months 6 months 1 month

Viruses 6 months 3 months 2 months 1 month

Protozoa 10 days 2 days 5 days 2 days

Helminths 7 years 2 years 5 months 1 month

Reductions due to Processing

Anaerobic digestion

Lime treatment

composting, pasteurize

Fecal coliform

1/30 >>1/100 >>1/100

Pathogenic bacteria

1/10 >>1/100 >>1/100

enterovirus 1/10 >>1/100 >>1/100

Helminth eggs

1/3 ?, 1/10 >>1/100

Approach to Controlling Risk from Pathogens

Class A

Eliminate pathogens by extreme processing such as pasteurization. Then reduce vector attraction.

Class B

Reduce pathogens by conventional processing. Reduce vector attraction. Surround use with restrictions that eliminate all paths to man, crops and animals.

VAR AND PR

• Pathogen Reduction (PR) and Vector Attraction Reduction (VAR) are required.

• For Class A, PR must take place before or at the same time as VAR.

Vector Attraction Reduction (VAR) Methods

• Reduce volatile solids content• Reduce specific oxygen uptake rate• Compost for 14d above 400C• Raise pH above 12, >11.5 at 24h.• Dry to 90%, 75%, depending on sludge.• Inject below the soil surface• Surface apply but plow in promptly(Details are found in 40CFR Part 503)

PFRP Processes (Class A)

• Composting• Heat drying• Heat treatment• Thermophilic aerobic digestion• Irradiation• Pasteurization• High pH and temperature/time treatment(for each process, minimum processing

conditions are specified in 40CFR PART503)

ADDITIONAL CLASS A PROCESSES

• Prior Testing for Enteric Virus & Viable Helminth

• Routine monitoring of each batch of treated sewage sludge.

• Use PFRP Equivalent Process.

Class B Biosolids Microbiological Criteria

• Reduce fecal coliform density to less than 2,000,000 per gram of solids. This is 1/100 of density in wastewater solids.

• OR, treat the sludge by a specific stabilization process defined in the regulation (a PSRP)

PSRP PROCESSES

• Aerobic Digestion

• Air Drying

• Anaerobic Digestion

• Composting

• Lime Stabilization

(for each process, specific minimum conditions are specified)

Class B Restrictions: Site Access

• If high public use (ball field), no public access for 12 months.

• If low public access ( a farm), no public access for 30 days.

Class B Site Restrictions: Harvesting

• Above-ground food crops that touch the soil, 14 months after application

• Below-ground food crops, 20 months if first 4 months are on soil surface. 38 months if < 4 months on surface.

• No crops harvested within 30 days of application.

Class B Restrictions: Turf and Grazing

• Turf: If high public access (a front lawn), no harvest before one year after application.

• Grazing: No grazing until 30 days after application.

Is the Practice of LA safe?

• Comment: The US NRC says the rule is sufficiently protective (with caveats)

• Objection: How can one rule fit the entire United States?

• Any state can add more stringent requirements tailored to their conditions.

Some State Actions

• Specify distance to water table (Florida)

• Specify maximum allowable slope (NY)

• Decreased some allowable metal concentrations (NY, Nova Scotia)

• Increased most time restrictions

Problems with 40CFR PART 503

• Hard to modify the regulation• Are the processes working properly• PSRP should have been dropped• Grazing restrictions should key to temp.• Aerobic digestion PFRP should be fixed• Low public use access restriction for Class B

should be modified• Slow pace of Federal research

Improving Reliability

• Increase Government oversight, toughen penalties

• Require certification of satisfactory operation by independent evaluators (e.g., the Biosolids Partnership)

Concn.: Exceptional Qual. BiosolidsMETAL (mg/kg) NOVA SCOTIA US EPA

Arsenic 13 41

Cadmium 3 39

Chromium 210 1200

Cobalt 34

Copper 400 1500

Mercury 0.8 17

Molybdenum 5 18

Nickel 62 420

Lead 150 300

Selenium 2 36

Zinc 700 2800

What the Federal Rule Establishes

• General requirements (must give details about the site, sludge, planned practice)

• Pollutant limits (e.g., max. metal concns.)

• Management practices (e.g., 10m from US waters)

• Monitoring frequency

More on what the FR establishes

• Operatinal standards (spells out how one must achieve pathogen and VA reduction)

• Recordkeeping (Certify rule is being kept under penalty of law if not true)

• Reporting (If > 1 MGD, a yearly report)

Approach to Controlling Risk from Metals to Man and Soil

• Determine metal concentrations in sludge

• Apply at agronomic rate (to prevent excessive N/P/K loading)

• Establish max. concn. in the biosolids

• Establish max. annual and total loading to the soil.

• Establish concentration below which no harm will occur.

Class A Sludge Microbiological Criteria

• Salmonella– < 3 MPN per 4 grams of TS

• Fecal Coliforms– < 1000 MPN per gram of TS

• Enteric Viruses– < 1 plaque forming unit per 4 grams of TS

• Viable Helminth Ova– < 1 per 4 grams of TS