successful approaches to biosolids · pdf file∗solid/dewatered form ... address...
TRANSCRIPT
Successful Approaches to Biosolids Composting
The Compost Council of CanadaSeptember 19-21, 2011
1. WeCare Organics2. Wastewater Summary3. Composting Operations
Composting Processes Composting Systems and Technologies Process Monitoring and Control End Product Marketing and Sales Health and Safety Equipment Selection and Maintenance Staffing
1. Site Selection and Community Relations
Outline
∗ Headquartered outside of Syracuse, New York∗ Four main operating groups• WeCare Facilities Operations Group (WFOG)• WeCare Product Marketing Group (WPMG)• WeCare Technology Group (WTG)• WeCare Residual Services Group (WRSG)
∗ Currently manage over 15 organic waste sites/facilities and service many others
∗ Sister companies include• WeCare Transportation• Blue Heron Construction
WeCare Organics
Wastewater Summary
Source: City of Livermore
∗ Liquid form (~0.5% to 5% solids)∗ Solid/Dewatered form (~5% to 25%+ solids)∗ Regulations by USEPA, or equivalent• Pathogen reduction, Vector attraction, Pollutant limits
∗ ~8 million dry tons per year (60m wet tons)∗ Use & Disposal• 43% Spread to land• 12% Advanced treatment (alkaline, composting, drying)• 45% Disposed (landfill/incineration)
Biosolids
1. Feedstock Characterization2. Pre-Processing3. Active Composting4. Compost Curing5. Screening6. Odor Control
Composting Processes
∗ Quantities• Mass/ volume per day
∗ Properties• Bulk density (weight per unit volume)• Moisture content• Nutrients (C&N, also O and micronutrients)• Contaminants
∗ Appropriate feedstock ‘recipes’/design criteria∗ Seasonal Variations• Biosolids• Amendment
Feedstock Characterization
∗ Contaminant Recovery• Protect equipment from damage• Easier to remove at front end
∗ Preparation• Grinding amendment• Inoculum (compost recycle)
∗ Mixing• Combine recipe ingredients• Complete and homogenous
Pre-Processing
∗ Biological process (~30+ days)∗ Objectives• Degradation/ stabilization of organic matter• Pathogen destruction• Remove odor potential
∗ Changes during process• Mix becomes more uniform• Volume reductions (25%-50%)• Weight loss (40%-80%)• C:N declines• N loss as ammonia
Active Composting
∗ Composted material is stable, not mature• Stability = stage of decomposition• Maturity = biochemical state of the compost
∗ Maturing removes potentially phytotoxic intermediate compounds of decomposition (i.e., NH3, VFAs)
∗ Extent (maturity) of curing defined by market∗ Time: 30 – 60+ days
Curing
∗ Equipment used to remove ‘large’ particles from finished compost before it is sold
∗ Screen size (e.g., 1/4”, 3/8”, 1”) vary on what the market for that material is
∗ Types• Trommel Screen• Shaker deck• Star screen
Screening
∗ Odor quantification• Concentration, Intensity, Persistence, Character, Hedonic tone
∗ Can perform odor modeling for site layout or mitigation
∗ Implement odor treatment technologies• Biofiltration• Windrow covers• Chemical scrubbers• Masking agents• “Neutralizers”/ counteractants
Odor Control
∗ Common Odors and Cause• Ammonia = Too much nitrogen• Amines (fishy) = Anaerobic conditions• Sulfides (rotten egg) = Anaerobic conditions• Volatile Fatty Acids, VFAs (gym bag) = Anaerobic conditions
∗ Factors to Consider• Composting rate/ size• Moisture• Aeration and turning• Recipe• Weather conditions
Odor Control
Common Biosolids Compost Methods1. Turned Windrows
2. Aerated static pile
3. In-vessel composting
Composting Systems and Technologies
∗ Mixed materials are placed in windrows which are agitated or turned
∗ Turning vital• Rebuilds porosity• Releases trapped heat, water and gases• Exchanges surface with interior materials
∗ Windrow Management• Important to maintain turning schedule (temp and odor
control)
Turned Windrows
∗ Designed to be a piped aeration system, using a blower to supply air to the materials
∗ No turning or agitation of the materials occurs once the pile is formed
∗ Can be positive or negative pressure air, depending on facility specifications
Aerated Static Pile
∗ Confine the materials within a building, container, or vessel
∗ Rely on a variety of forced aeration and mechanical turning techniques to speed up the process
∗ Bin composting, rectangular agitated beds, silos, rotating drums
In-Vessel
∗ Common Parameters• Temperature, Moisture, Oxygen
∗ Develop Quality Assurance/ Quality Control plan∗ Perform process monitoring to verify:• Product safety standards• Product market specs/ standards• Process control• Regulatory compliance
∗ Develop a Site Monitoring and Sampling Plan∗ Develop a Site Contingency Plan
Process Monitoring and Control
Conventional∗ Golf courses∗ Athletic/turf fields∗ Greenhouses∗ Retail∗ Roof-top gardens∗ Mine reclamation∗ LandscapingWeCare composts and sells ~250,000 tons of biosolids annually
Product Marketing
Considerations∗ Regional – address local concerns• Environmental• Nuisance (e.g., odor, trucking)
∗ Economic – address financial drivers• Treatment options• Market share
∗ Physical – address location constraints• Distance to end user• Climatic conditions
Product End Use
Health and Safety
∗ Know Concerns• Dust, Noise, Equipment, sanitation, etc.
∗ Minimizing the risks• Pick the right site and equipment• Provide Personal Protective Equipment (PPE)• Maintain a good housekeeping program
∗ Safety in compost production• Operate equipment appropriately• Train and communicate with personnel
∗ Adhere to laws and regulations
Health and Safety
Fires∗ Typical compost materials ignite when• Moisture content <40%• Just enough oxygen present (vent holes)
∗ Ignition source• Mechanical (sparks, equipment, cigarette)• Biological (uncontrolled microbial activity)• Temps >158-176F spontaneous combustion occurs
Contaminants∗ Visually inspect loads as they are received∗ Charge additional fees for contamination
Health and Safety
Considerations∗ Production∗ Simplicity of operation &
maintenance∗ Product support∗ Durability∗ Relationship with
manufacturer
Equipment Selection
Considerations∗ Price∗ Safety∗ Reliability∗ References∗ Reputation
∗ Pre Process equipment• Weigh scales• Grinding/ mixing equipment• Loading/ material handling equipment
∗ In process equipment• Compost turners/ loaders• Aeration equipment• Process management equipment
∗ Post process equipment• Screening equipment• Bagging equipment
Equipment Categories
Maintenance & Contingency!
∗ Need mechanical skill and high attention to detail∗ Large expense is operations and making sure all
tasks are run efficiently∗ Need to make sure all equipment is operational
with minimal downtime∗ Administer training∗ Certification up-keep∗ Mix roles (for covering…do not want back-up!)
Staffing
Siting
∗ The most critical issue in facility development∗ Need 2-5xs the land you need for facility∗ Try for >1,000’ to any sensitive receptors• Houses, churches, shopping centers, etc.• Surround facility with wooded buffers
∗ Try to be <5 miles from major arterial roads∗ Acquire necessary permits (state solid waste, ag,
water quality, local zoning, etc.)∗ Setbacks!• Environmental, infrastructure (e.g., airports), etc
Siting
∗ Site location• Roads suitable for truck traffic• Convenient to source of feedstocks• Not in a residential area
∗ Sizing• Anticipated volume and equipment needs• Future growth
∗ Site characteristics• Level to slightly sloped ground• Firm drainable soil• Utilities convenient
Site Selection
∗ Ground and surface water pollution∗ Property value reduction∗ Migration of airborne fungal spores and pathogens∗ Odor∗ Excessive truck traffic∗ Noise∗ Vectors: rodents and insects
Causes of Concern/ Complaints
Addressing Concerns and Complaints∗ Involve public in site selection and design∗ Communication• Hold open meetings• Send letters• Set-up a hotline and website
∗ Hold “Open House’ tours∗ Do not hide what you are doing
Community Relations
