productive uses of wastewater sludge N Denver Boulder Greeley Fort Collins productive uses design prototype regional network parameters Composted biosolids go through a cycle of three stages; mixing, composting, and curing. Once the composted biosolids are curated, the soil is ready for sale and distribution. From start the finish, a single load of sludge takes approximately six weeks to complete the composting cycle. Denver’s wastewater reclamation facility processes up to 140 million gallons of water daily, resulting in the production of 68 dry tons of sludge. The current sludge pro- cessing procedure, anaerobic di- gestion, of biosolids at the Denver facility requires large amounts of energy resulting in annual produc- tion costs of over a million dollars. With increasing population in the South Platte River Basin, energy use at wastewater facilities is ex- pected to increase. Composting sludge is one of the most productive ways to cut on down on energy use in wastewater treatment processes. By switching from the conventional anaerobic process to a composting system, thousands of dollars can be saved every year. Not only does com- posting reduce energy use and costs, but composted biosolids are productive in a variety of ways. Composting facilities help to reduce greenhouse gas emis- sions that are produced during the anaerobic digestion process. Com- monly, composted biosolids can be applied to agricultural land to restore eroded soils and degraded crops, yet compost can be used to fertilize household lawns, remedi- ate brownfields, restore wetland habitats, and cap landfills. KrapPARK is a project that pro- poses a system of composting facilities to create a more energy efficient wastewater treatment process. The compost web follows sludge from the beginning until final distribution to productive uses focusing in the Boulder, CO area. The network is easily replicable and can be linked to other waste- water facilities creating an energy efficient and productive landscape. Metro Wastewater Reclamation District, Denver, CO 210,000,000 gallons of water distributed daily by Denver Water 140,000,000 gallons of wastewater treated daily by Metro Wastewater Reclamation District 350 gallons of water used daily by a single family home Energy Use 29 kWh daily average home consumption 24189 kWh daily secondary wastewater process 834 homes KrapPARK Regional Compost Center is located ten miles east of downtown Boulder and is the first phase of the proposed composting network. KrapPARK mixes sludge from Boulder Wastewater Treatment Facility on site, as well as green waste delivered by the public. The mixture is composted and con- verted into nutrient rich soil that is later sold for use by both public and private entities. KrapPARK is a unique facility because it involves members of the community which facilitates sustainable solutions for waste disposal and productive uses for wastewater byproducts. Boulder Wastewater Treatment Facility Boulder Composting Network Captain Jack Mine Reclamation Site Waldon Ponds Wildlife Habitat Denver Regional Landfill Boulder Regional Compost Center Park Park TOILET SEWER PRODUCTIVE USES WASTE WATER FACILITY COMPOST FACILITY Landfill Capping Composted biosolids have the most suitable structure for landfill capping projects. - The soil structure allows for appropriate root penetration to help prevent leachate problems - Composted soils have the richest amount of nitrogen and other nutrients to provide optimal growing conditions - Capping with compost in evapotranspiration caps allows for the waste and garbage to decompose below the surface garbage foundation composted soils Evapotranspiration Cap Composting Web At a regional scale, the project consists of a rhizomatous web of linkages between existing wastewater treatment facilities and proposed composting facilities. The composting facilities are strategically placed near transportation infrastructure and agricultural lands, as well as centralized among existing wastewater treatment facilities state-wide. The composting nodes facilitate the collection, distribution, and productive uses of wastewater byproducts for both public and private entities. Biosolids are treated sewage sludge that meets the EPA pollutant and pathogen requirements for land application and surface disposal. Composted Biosolids Composted biosolids are organically rich soils that contain a well-balanced array of micronutirents that are capable of conditioning degraded soils through land application. Sludge refers to the residual solid or semi- solid material separated from wastewater during wastewater treatment processes. Sludge Biosolids Composted biosolids are an effective method of remediating toxic soils contaminated by industrial pollution because they: - Increase soil fertility - Correct soil pH levels - Improve physical properties of soil Oxygen K Mg Na S Fe P,N Ca C Al Si Mg Al S K Oxygen Carbon Na Fe P N H Ca Si Carbon Oxygen K Mg Na S Fe P,N Ca Al Si Mg Al S K Oxygen Na Fe P N H Ca Si Average Soil Composted Biosolids Brownfield Reclamation evapotranspiration Polishing Wetland microbes (biofilm) benthic layer south platte river treated wastewater composted biosolids Composted biosolids can be used in the production of floating wetland islands that are used to restore wetlands. - Islands act as a water purifier, collecting toxins from the polluted wetland - Wildlife habitats are restored through the addition of floating islands Composted Biosolid Island Wetland Restoration Transportation Network Denver Boulder Fort Collins Greeley Composting facilities are located nearby transportation infrastructure to ensure efficiency and convenience in the collection of wastewater byproducts and the distribution of composted biosolids throughout Colorado. N Highways Railroads Soil Water Capacities Because the application of composted biosolids to a soil increases the available water capacity, which helps plants survive longer in droughty conditions, the composting facilities are strategically located on or near soils with low available water capacities. N 0.00-0.02 0.03-0.09 0.10-0.14 0.15-0.17 0.18-0.20 Crop Nitrogen Requirements Agricultural crops require varying amounts of nitrogen in their soils. Because additional micronutrients can be added into the biosolid mixture, composted biosolids are an effective method of providing nitrogen to crops. For this reason, the composting facilities are located near agricultural lands. Low High N Composting Web The proposed composting facilities are also located near existing wastewater treatment plants to facilitate the exchange of wastewater byproducts to be converted into useful products by the composting facilities. Existing Wastewater Treatment Facilities Proposed Composting Facilities N Captain Jack Mine Reclamation Site Denver Regional Landfill Waldon Ponds Wildlife Habitat Wastewater Treatment Cycle Conventional Sludge Treatment Process Proposed Sludge Treatment Process Benefits of Sludge Composting As Compared to Conventional Anaerobic Digestion Processes 68.50 1,253.55 $100.28 $36,602.00 dry tons daily daily kWh daily expenses yearly expenses Proposed Process Aerated Pile Composting 18.3 kWh per dry ton 68.50 38,360 $3,038.80 $1,120,112.00 dry tons daily daily kWh daily expenses yearly expenses Current Process Anaerobic Digestion 560 kWh per dry ton daily electrical savings daily monetary savings yearly monetary savings 37,106 kWh $2,938.52 $1,072,370.00 Savings Sludge Processing Colorado imports about 34,000 dry tons of sludge annually. After processing, Colorado uses about 102,000 dry tons of sludge beneficially each year. Sludge Importing 2007 Biosolid Use in Colorado Park Park Incentives Affiliate with Trash Tax in Boulder to support entities transitioning to zero waste Establishing a program that trades compost for public waste Create grants to support research at compost facilities Government tax breaks for reducing greenhouse gas emissions Weeks 4-7 Weeks 8-11 Weeks 12-15 Weeks 1-3 Composting Cycle Raw Sludge Mix Curing of Compost Final Composted Biosolids Goals & Objectives Reduce energy requirements through alternative sludge processing Reduce greenhouse emissions and landfill disposal of sludge and biosolids Reduce imports of biosolids to the South Platte River Basin Engage community through interactive green waste sorting and composting processes Utilize productive uses for composted sludge -Agricultural Application -Brownfield Reclamation -Landfill Capping -Wetland Restoration -Residential application N Circulation Public Delivery Trucks Composting Equipment Public Compost Center Sludge Mixing Center Aerated Blower Perforated Pipe Air Circulation from Blower Raw Compost Mixture Finished Compost Compost Distribution Center Recycling Center Park Park Composting Center Prototype Aerated Static Pile Aerated Static Composting Piles Rachel Barth & Kylie Harper | LAR 648 Mile High Water: Design Strategies for Denver’s Drylands | Professor Canfield | Kansas State University | Fall 2011