The primary function of wastewater treatment ponds is to remove biodegradable solids (BOD) from effluent. These ponds work by transferring effluent from an anaerobic pond to a facultative recirculating pond. In this process, water in the upper layer of the pond receives oxygen from natural diffusion, wind mixing, and algae-driven photosynthesis. Water in the lower layer remains anaerobic and settleable solids accumulate on the bottom. The mixture of aerobic and anaerobic organisms results in a BOD reduction of up to 75%.
The wastewater stabilization Pondovac 5 may be thirty to fifty feet deep and contain a combination of salt and mineral-based wastewater. Such ponds are typically used in mining and oilfield wastewater treatment. The full depth mixing condition of the pond occurs when the water column temperatures converge during the spring and fall seasons, although it can occur at any time. The depth of the ponds is usually less than one acre.
To make wastewater odor-free, facultative ponds are designed to reduce the BOD content of wastewater before it enters the recirculating pond. In addition, these ponds should be lined with an impervious material, such as clay. If the wastewater is contaminated by garbage, a berm or fence surrounding the pond may be necessary. A fence around the pond may also be necessary to prevent humans and animals from entering the pond.
The amount of light that can penetrate the pond’s water column will vary based on the season. In summer, light penetration is low and windy, which will increase the concentration of algae. In spring, however, temperature differences are high and light penetration can vary by several degrees. During this time, wind-driven ventilation in the pond is more effective. The ventilation of the pond can also improve effluent quality.
Maturation ponds have several main functions. The biofilms in the storage ponds are enriched with Proteobacteria and other unidentifiable bacteria. However, the phosphorus in storage pond water can be reduced by algae harvesting. The biofilms in these ponds may also be used for algae production. Further, a variety of bacteria and algae may be present in these ponds.
A study of 71 wastewater treatment pond systems found that virus removal was correlated with the hydraulic retention time. However, the correlation between the length of retention and the reduction of virus count was weak to moderate. Virus removal was achieved in one log10 for retention of 14.5-20.9 days (95th percentile value). The authors also investigated the mechanisms involved in virus removal. However, sedimentation did not seem to be a significant factor in the removal of viruses in some ponds.
Sulfur is an important chemical element in organic materials. In an aerobic process, it is converted to sulfate, while in anaerobic digestion, it becomes sulfide. These two compounds have varying odors. Controlling the odor is key to the process. The operation of the wastewater treatment ponds will determine the type of biogas that is produced. For example, in a typical wastewater treatment pond, the use of oxygen is essential for reducing sulfide levels.