Wastewater Basics

Wastewater Basics

Whether using conventional treatment or advanced treatment, wastewater follows a specific treatment path in order to meet water quality standards.

Primary Treatment separates the solid matter from the liquid waste. This 'wastewater', composed of nutrients, liquid wastes and primarily water, can be treated more quickly than solid waste which stays in the system until it breaks down.

Secondary Treatment exposes wastewater to aerobic bacteria in order to break down suspended organic matter, pathogens and other contaminants. Sewage treatment plants often use baffles with a special film coating of aerobic bacteria. Wetlands habitats naturally supply this aerobic bacteria through the microbes and bacteria found there.

Tertiary Treatment is the last step and involves the removal of nutrients from the wastewater. Many sewage treatment plants neglect this last step because of the costs involved. Nutrient removal is an important method of curtailing downstream effects such as eutrophication and algal blooms, which destroy ecosystems and habitats. Many Advanced wastewater treatment, include tertiary treatment as a standard practice.


Vegetation

There is a lot of freedom in choosing vegetation for the wastewater treatment beds. The plant design can please almost any aesthetic and may be simply decorative or useful. Trees, shrubs, flowering, herbaceous and grass species all flourish.
Some planting options:
· Landscape ornamentals
· NC natives
· Cut flowers
· Wildlife habitat for birds, butterflies, bees
Plants grown in water treatment cells assist in the biological treatment of the water. Plants act like pumps, converting sunlight into chemical energy in the form of sugars, stored in the roots, and carrying oxygen from their leaves to their roots.

The most essential role of plants in wastewater treatment is as a habitat for microbes. Pollutant eating microbes colonize in this food and oxygen rich zone surrounding the root surface. Microbes are very efficient at breaking down pollutants and converting them into harmless gases.
Important to efficient treatment is plant diversity and a variety of root types and depths, from shallow rooted ground covers to medium rooted shrub species. Wetland plants tend to have extensive root systems that foster large colonies of microbes.