Co-utilization or blending of residuals offers a unique opportunity to develop products with particular characteristics that are able to target specific customer needs. The very notion of deliberately blending by-products suggests that the recycling and beneficial reuse industries are taking a quantitative step forward towards developing products rather than simply reusing residuals. At the same time that this step provides unique opportunities, it also presents unique challenges. The science associated with the beneficial use of one product may not apply when that product is mixed with...