John Classen North Carolina State University

Publish Date: June 3, 2006

While the primary method of swine manure management in the United States is temporary storage followed by land application as crop fertilizer, there is increasing interest in recovering energy and nutrients from manures prior to land application. Insufficient nutrient assimilation capacity in nearby crop land, or interest in adding value to swine manure beyond the fertilizer value, are among the reasons that alternative management strategies may be sought. Producers who consider alternative manure uses will find many options available. This publication describes several energy and nutrient recovery processes currently available. Each process is explained and primary issues that a producer should consider with each process are discussed.

Publish Date: June 3, 2006

A solids separator removes solids from mixtures of solids and liquids. It is appropriate to think of a solids separator as a device that breaks an incoming waste stream into two separate flows: one with a solids content lower than the original waste stream, the other with a solids content higher than the original waste stream (Figure 1). Depending on the type of separator used, the lower-solids content waste stream may be called effluent, separated liquids, or liquor. Likewise, the higher-solids stream might be called sludge, grit, separated solids, or cake. Individual manufacturers may use different terms to describe the same stream. To keep things simple, in this paper we will call the stream entering a solids separator influent, the low solids stream leaving the separator liquor, and the high solids stream cake. Devices remove solids by a number of methods: settling material to the bottom of a waste stream, screening larger particles out of the stream, and floating light material to the top of the stream, to name a few. Some devices may perform more than one type of removal and create three or more waste streams, the idea of a solids separator is to create at least one stream of low-solids liquor.