Agenda - 10-08-1991 - Laserfiche WebLink

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Class V11 S stems - Sludge Application Sites - The waste treatment process represented by sludge application is vastly different than the other types of treatment processes outlined above. The first six classifications represent a primary treatment process, in that the treatment processes described are the initial phase of treatment. Land application of sludge is analogous to the conventional, low pressure or spray irrigation nitrification field. The solid residue which is removed from package waste treatment plants and from municipal waste treatment plants is called sludge. Sludge is a very different material from septage and does not exhibit most of the well known unpleasant characteristics of septage. Although sludge is the by- product of a waste treatment process, generally it has undergone a tightly controlled aerobic or anaerobic digestion (decomposition) process. By the time waste treatment sludge is removed from the treatment process, it is considered to be "stabilized" in that the process of microbiological decomposition of organic material is nearly complete and activity by bacteria and other microbes organisms is very slight. Nutrients, including nitrogenc potassium and phosphorus, and micronutrients, including iron, copper and zinc, are also found in substantial quantities in waste treatment sludge. The US EPA has determined that these nutrients are generally present in sufficient quantities to provide a potential beneficial agricultural use for sludge as a fertilizer. At this time two methods of sludge disposal are considered acceptable by,the US EPA: incineration and land application. Incineration is an expensive alternative, in that the equipment which must be used to insure that toxicants are not discharged to the atmosphere is very costly to install and maintain. Land application of sludge is the method of disposal preferred by the EPA and most other regulatory agencies concerned with environmental protection. In a land application process, sludge.can be land applied to surface or subsurface as either a solid or highly liquified material. There are two types of'sites for the land application of sludges agricultural application sites and dedicated sites. There are no dedicated sites for land application of sludge in Orange County, so this process will not be described. Agricultural application of waste treatment sludge is a very t10tly regulated process. There are many limitations on the agricultural uses of sludge sites. An important limitation on a sludge application site owner is that any crop grown on the site cannot be used directly in the human food chain. 10