Biosolids and Composting in Midwest City, OK Owner: Midwest City Municipal Authority Midwest City, Oklahoma Design Engineer: Black & Veatch Corporation Constructed By: Garney Companies, Inc.
The Problem: Sludge is taking over the plant 2009: Field Apply liquid sludge Availability of land Only apply at convenience of landowner Farming activities Cold weather Rain Seasons
The Problem: Sludge is taking over the plant Application Fleet Showing its age Travel Distances Fuel, Emissions Maintenance and repairs
The Problem: Sludge is taking over the plant Digesters 4 Useable tanks-2m Gal 1.0% Solids Grit & Debris problems for mixing Energy wasted to heat water instead of sludge
The Problem: Sludge is taking over the plant Clarifiers Poor Efficiency Grit & Debris issues Secondary Sludge was 0.5% solids
The Problem: Sludge is taking over the plant Grit and Debris removal Grit removal was approx. 5% efficient Grinders worked well, but the debris was passed on into the plant
The Problem: Yard waste is taking up space. Yard waste storage areas are full Years of severe weather and ice storms More on the way No good place for it to go Storage on city property Hard to control dumping Susceptible to fire Not allowed to control burn
Solving the Problem: A Remodeled Facility
A remodeled facility. 11 New Structures, 21 Renovated, 5 Demolished 2 Miles of Yard pipe, 3 Miles Electrical Ductbank
Getting more out. Debris removal New fine screens remove trash from the flowstream Compactors press water out of the trash before discharging into dumpsters for haul-off
Getting more out. Grit removal Grit removal efficiency is estimated at 85-90% Water is introduced through a channel to induce a vortex, sending grit to center Grit is pumped off bottom, washed, and conveyed to dumpsters as well Fewer inorganic solids are allowed to reach the clarifiers and sludge process, freeing up space and easing up on equipment
Getting more out. All new Clarifier mechanisms: more efficient and better design Approx. 4% Solids from Primary Clarifiers
Getting more out. Drum Thickening Yields 5-7% Solids Polymer assisted Secondary sludge sent to thicken before heading to digesters More water in biosolids handling = more wasted energy in moving and heating
Getting more out. New Mixing systems in all 4 digesters New Gas-Collection Domes Increased Capacity due to higher % solids
Getting more out. Methane Collection, Use, and Flare Less energy needed to heat water and sludge, less water is passing through. Environmentally friendly use of generated methane to operate boilers for sludge heating. Excess is flared off
Getting more out. Dewatering Digested Sludge goes to Rotary Presses Greatly reducing material handling by taking more water out. Polymer Assisted Dry Cake sludge produced, what are we going to do with it??
Kill two birds (and then some?) Take two wastes and make a desirable product Composting takes the cake sludge from the presses and yard waste from the city to yield an E-coli-free, salmonella-free, fertile product. Year-round activity Plant has full control over treatment Less volume due to natural degradation Possibly create a revenue stream
Kill two birds (and then some?) New rolling stock Loaders Chipper Trommel Screen Roto-Mix truck
Kill two birds (and then some?) New scale to measure outbound Compost Receiving Area for income yard waste from tree services, clean up crews and citizens Use of product as fertilizer on city grounds Possibly create a revenue stream by selling finish product
Kill two birds (and then some?) Siemens (now Evoqua) 2 meter IPS Composting System 4 Bays, 200 long Housed in a 35,000 sf building Office, Laboratory, Storage, Electrical Room
Kill two birds (and then some?) Aeration System 16 blowers 4 Temperature monitoring zones Gravel bed acts as diffuser Keep temps down Supply fresh air to facilitate aerobic activity
Kill two birds (and then some?) Amendment mixed with sludge and loaded into the bays. Agitator tills, mixes, and conveys compost down the bays Temperature is controlled by an aeration system in gravel bed below the mixture Approx. 21 days from start to finish
Finished Compost
Questions?