Title
Discussion regarding the future of composting at the Central Wastewater Treatment Plant.
Summary
This item has been included on the agenda to allow for discussion.
The Central Wastewater Treatment Plant has been running a windrow composting operation since the late 1990s. This process involves taking our dewatered solids from the Central wastewater treatment process and mixing it with wood chips in a specific ratio to make a compostable product. This mixture is then formed into a pile called a windrow which must then be turned multiple times throughout a month to “cook” any microorganisms that may be present in the solids. While this seems to be a simple process, the turning of the windrows can be complicated. Turning the piles must both aerate the piles to keep oxygen flowing into the pile to keep the microorganisms active that are breaking down the waste products of the sludge/solids and also keep the moisture content stable within the windrow. The moisture levels must stay within specified guidelines in order to not create a pile that is too dry and overheat the compost or too wet and not allow the pile to heat up enough to “cook” everything. Once the windrow has gone through roughly one month of turning and curing, the compost must be tested to have an E.Coli level below 1,000 MPN/gram in order for it to be considered a Class A Compost that we can distribute to residents. In the span of three weekends of the Recycle Center being open in May, we totaled 36 customer pick ups of compost. This is typical traffic for our compost.
This process is currently done with a small loader that is used to turn the piles and with a trommel screen that is used to separate the compost material from the wood chips that we use. The loader isn’t intended to be used to turn compost windrows and will produce uneven results in our various test piles where we sometimes will have too much moisture or too little that is due to being unable to effectively turn the en...
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