When it comes to WTE, collection is key

In my last column, I discussed how roughly two-thirds of every solid waste management dollar is spent on collecting waste or recyclables, and how collection needs to be as efficient as possible. Additionally, the way in which residential and commercial waste is collected can significantly affect its resulting quality as a fuel. Contamination, exposure to the elements, set-out methods and container type all influence processing requirements. Most advancing waste conversion technologies prefer a high-quality feedstock for making their chemical, fuel or energy products. The poorer quality the set-outs, the more robust the processing systems will need to be, such as including drying as a necessary and expensive step. Therefore, the right collection method makes a difference. If a community is in the process of developing a conversion technology facility, evaluating waste collection well before its doors open can make a big difference in the facility’s success.

The debate between one-bin, two-bin, three-bin and even four-bin systems* is growing, as communities like Houston and Montgomery, Alabama, have taken steps to change their collection approaches to match the selected processing approaches. This is done, in large part, to have all waste and recyclables collected together to be processed out mechanically, yielding streams of recyclables, organics and residue. Each of these streams can then be marketed for sale, further composted, directed to anaerobic digestion, used as a fuel to replace coal or used for other fuel/energy applications. The cost savings accrued from eliminating extra collection routes is likely higher than the extra cost for this higher level of processing, producing a net savings. Eliminating routes also reduces greenhouse gas emissions from burning diesel or compressed natural gas (CNG).

Returning to the one-bin approach harkens back to the days when mixed waste processing facilities in places like New Orleans and San Marcos, California, attempted to unscramble municipal solid waste (MSW). Except now, with the help of more sophisticated processing unit operations coupled with computerized control systems, there is greater hope that these systems can separate out a marketable stream of recoverable materials. The key to making the economics work will be accurate evaluation of the materials received and the quality and marketability of the products coming out.

One of the first adjustments to be made to the collection side is the transition from a multicart/bin collection system to a single container. Arguably, the biggest hurdle communities are likely to encounter stems not from logistics but from public perception. Education and outreach programs will need to be thoughtful and robust, and community leaders must be prepared for the pushback that may occur as residents wonder whether the recyclables they used to separate will actually be recycled. Building trust in this new method, which is counter to the conditioning of the last 20-plus years, will require significant investment in re-education. If these facilities are successful in increasing diversion, and the public can learn to trust a one-bin approach, then we could see recycling rates soar even higher, while we create new and better feedstocks for fuels/energy recovery and move closer to zero-waste-to-landfill.

* The reference to the number of bins can also be interpreted as meaning separate set-outs. For example, the four-bin system refers to separate set-outs for waste, yard waste/organics, mixed paper, and comingled containers. Bulk waste collections are excluded in this reference, although a separate collection service is often provided.

Research assistance provided by Elizabeth Rice consultant II, GBB.

Harvey Gershman is president of Gershman, Brickner & Bratton Inc., solid waste management consultants; hgershman@gbbinc.com.