8.4. Disposal Options

Some residuals generated in treatment plants; such as leaves, limbs, logs, plastic bottles, and other large floating debris which are separated from initial screening process, are relatively easy to handle and can be disposed of at conventional solid waste landfills. However, most other residual waste streams are more complex and require advanced processing and disposal methods to protect human health and the environment.Selection of an alternative disposal method should be based on both economic and regulatory bases. The type and characteristics of slugde generated is also important in deciding disposal or reuse alternative. Besides landfilling, reuse as a soil amendment, discharge to a wastewater collection system, codisposal with wastewater biosolids and reuse in building or fill materials are available alternatives for disposal or reuse of residuals.The most common disposal method for water treatment plant sludge is landfilling. Depending on test solutions to determine whether it is toxic or not, the type of landfill is decided for final disposal.For land application (reuse as soil amendment) of water treatment plant residuals, it should be tested to see whether it is hazardous or not, as well. The crop being grown, chemistry of the soil, and sludge properties are important in deciding land application method. Coagulant sludge, lime-soda softening sludge, nanofiltration concentrate and slow sand filter washing can be applied to land. The ideal land application is on non-food chain crops, mine reclamation areas, and forests. However; it should be taken into consideration that land application can result in increased concentration of metals in the soil and thus groundwater and in less productive soils. Wastewater generated in water treatment processes, such as filter backwash water, can be recycled to the head of the source water treatment plant. To reduce the impact of intermittent high volume flows from backwashing operations, flow equalization is used. For brine waters, ocean disposal is an alternative.

To read more:

i.Drinking Water Treatment Plant Residuals Management Technical Report Summary of Residuals Generation, Treatment, and Disposal at Large Community Water Systems, United States Environmental Protection Agency, September 2011 EPA 820-R-11-003