Dairy plant waste water cannot immediately be drained into lakes, rivers or other water sources post-usage. Since effluent waste water from dairy factories contains high amounts of nutrients and organic matter, it must be painstakingly treated and cleansed before it can be released into the environment.
Dairy Plant Water Usage
Statistics quoted by Thomas Cutler of TR Cutler Inc. show that dairy-plant maintenance is water-intensive. Clean-in-place (CIP) systems continuously wash every plant tank, pipe and surface to ensure that microorganisms from dairy plant waste water do not contaminate the milk. Water is also employed to flush out contaminants from areas such as milk rooms, holding areas and barns. Since their facilities produce large amounts of highly contaminated waste water, dairy plant owners must employ a complex cleaning process to treat it.
Pretreatment
In the pretreatment phase, the raw waste water is filtered using a mechanical filter in order to remove the largest physical particles that could clog and damage the more delicate cleaning equipment in succeeding stages. The water is strained through a variety of screens to remove these large waste particles. The collected debris can be treated to render it environmentally benign and then disposed of; in some cases it can be used as fertilizer.
Primary Treatments
In this second stage, dairy waste water is fed into large tanks, which are utilized to allow smaller particles to collect as sediment at the bottom. In addition, floating debris or accumulated sludge, oils or fats from waste milk or the nutrients used in dairy plants--which may have congealed on the surface of the water--may also be removed. As in the previous stage, these treatment facilities are periodically cleansed of accumulated waste, which is recycled or reused as fertilizer whenever possible.
Secondary Treatments
After the smaller particles have been removed from the dairy waste water, it is treated further using biological methods. Microorganisms are employed to consume the organic contaminants that may not have been removed in previous treatments. In order to promote the growth and reproduction of these organisms, sewage water is often aerated. A certain amount of physical filtration may also be employed to remove particulates that may form as a result of the action of these microorganisms.
Tertiary Treatments
In this final treatment stage, dairy waste water is tested and cleansed one more time to ensure that it is as clean as possible before being discharged or reused. Waste water treatment facilities may employ a variety of methods, involving physical, chemical and biological treatments, to ensure that the water is as clean as possible before discharge. Water may also be disinfected using such methods as ultraviolet treatment or chlorine depending on its condition near the end of the cycle.
Discharge
Fully processed and treated dairy waste water can be used for such purposes as aquifer or groundwater replenishment. In many locations, such as Florida, such water is not considered suitable for drinking or even for release into surface bodies of water, and can only be utilized for such applications as landscape irrigation and fire-suppression purposes. However, such treated water may be eligible for Indirect Potable Use (IPU), in which it can be pumped out of the aquifer, treated once more and then utilized for drinking purposes.
