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Competency Area 8: Concentrated source pollution AEM

PO 77. Understand the advantages, disadvantages, and situational appropriateness of various options for handling milking center waste and/or other process waste waters.

  1. Septic systems/leach fields
  2. Vegetative filter areas
  3. Aerobic lagoon
  4. Organic filter beds
  5. Constructed wetlands
  6. Stone-filled trench
  7. Lime flocculation
  8. Spray irrigation
  9. Aerobic septic system
  10. Inclusion in liquid manure handling system

Stone filled trench – The advantage of using stone filled (infiltration) trenches is simplicity, but they are not generally suitable to accepting large volumes of process wastewater without being prohibitively large or being constructed in highly permeable, well drained soils, in which case there is potential for groundwater contamination. Stones are not particularly effective at P adsorption. When saturated conditions occur in the trench, septic and odorous conditions arise, and high inputs of organic materials may quickly clog areas of the trench.

Lime Flocculation – Lime flocculation is primarily a treatment method for treating and removing P from small volumes of milking center waste. Lime flocculation is not very effective at treating large volumes of other process wastewaters. The lime chemical input costs can be high, and the residual flocculated sludge must still be properly disposed.

Spray irrigation – The advantages of spray irrigation are large wastewater volumes are easily handled, it's the best method of distributing wastewater over large areas for effective nutrient removal and retention, and it can provide needed crop nutrients as part of a nutrient management plan. The disadvantages to spray irrigation, especially in the Northeast, are the wastewater likely needs to be stored for application during dry periods and it may be difficult and not acceptable to use during winter periods. With spray irrigation, any concentrated effluents may burn or contaminate vegetation, and these systems require pumps, a network of pipes, and pumping energy inputs.

Aerobic septic system – The aerobic septic system is similar to a regular septic system except that the effluent is decomposed and treated aerobically rather than anaerobically. An advantage of an aerobic septic system is the treated effluent is of better quality for land application or disposal to the leach field, so a leach field is less likely to plug. Thus, the aerobic septic system may be better suited to sites where an ordinary septic system and leach field would fail. Some disadvantages of the aerobic septic system are that it is more expensive to construct than a traditional septic system, and it's not generally practical for large wastewater volumes.

Inclusion in liquid manure handling system – When process wastewaters are added to the liquid manure handling system, which most often uses the aerobic lagoon approach discussed in 3 above, the lagoon needs to be increased in size to handle the additional wastewater volumes.