What is Pond treatment for Wastewater?
Pond treatment methods are used for disposal of raw sludge and treated effluent from the treatment unit. The un-stabilised sludge is stabilised in these ponds and treated effluent is further cleaned and used for recreational purposes.
Stabilization Pond Classification
Stabilization Ponds can be aerobic, anaerobic and facultative.
1: The aerobic pond is a shallow pond with a depth of less than 0.5 m and a BOD load of 40-120 kg/ha.d, maximizing the penetration of light throughout the depth of the liquid. Such ponds develop intensive algal growth.
2: Anaerobic ponds are used for pre-treatment of high-strength waste with a BOD load of 400-3000 kg/ha.d. Such ponds are built at a depth of 2.55 m as light intensity at the bottom of the lake is limited which arrests algal growth, The pond is aerobic on the surface but anaerobic at the bottom. They are often about 1 to 2 meters deep. The aerobic layer serves as an excellent protection against odours from the pond.
Purification Mechanism: Organic matter from wastewater is stabilized by both aerobic and anaerobic reactions. In the uppermost aerobic layer, where oxygen is supplied by photosynthesis of algae, precipitated and undissolved organic matter is oxidized to CO2 and water.
In addition, some of the final products of partial anaerobic degradation, such as volatile acids and alcohols that can penetrate the upper layers, are also periodically oxidized. Swelled sedimentation sludge mass and microbial synthesis in the aerobic layer, and dissolved and suspended organic matter in the lower layer are stabilized by conversion to methane, which escapes from the pond in the form of bubbles.
3: Facultative ponds generally vary from three to eight times in intensity. The detention time may be as quick as 25 days or so long as a hundred and eighty days. The number one operational hassle with facultative ponds is the presence of algae withinside of the effluent resulting in excessive overall suspended solids.
How can we use treated effluent?
The proper disposal of treatment plant effluent or reuse requirements is an essential part of planning and designing of wastewater treatment facilities around the world. Different methods of ultimate disposal of secondary effluents are discussed as follows.
1: Natural Evaporation
The process involves large impoundments with no discharge. Depending on the climatic conditions, large impoundments may be necessary if precipitation exceeds evaporation i.e. it rains too much that there may be a chance of water logging. Therefore, considerations must be given to total evaporation, storage requirements, and possible percolation and groundwater pollution. This method is especially advantageous when residual residue needs to be recovered, such as in brine treatment.
2: Groundwater recharge
Groundwater recharge methods include rapid infiltration through sewage treatment or reservoirs, intermittent infiltration, and direct injection. In either case, there is a risk of groundwater pollution. In addition, direct injection means high costs for treating wastewater and injection plants.
3: Recreation Lake
Wastewater from the secondary treatment facility is stored in the lagoon for about 30 days. The sewage from the lagoon is chlorinated and then permeates the area of ??sand and gravel, flows through it for about 0.5 km and is collected in the catchment area. It is discharged into lakes used for swimming, boating and fishing.
Aquaculture, or the production of aquatic organisms (both flora and fauna), has been practiced for centuries primarily for production of food, fibre and fertilizer. Lagoons are used for aquaculture, however, the uncontrolled spread of water hyacinths is itself a great concern because the flora can clog waterways and ruin water bodies.
5: Municipal Uses
Technology is now available to treat wastewater to the extent that it will meet drinking water quality standards. However, direct reuse of treated wastewater is practicable only on an emergency basis. Many natural bodies of water that are used for municipal water supply are also used for effluent disposal which is done to supplement the natural water resources by reusing the effluent many times before it finally flows to the sea.
6: Industrial Uses
Effluent has been successfully used as cooling water or boiler feed water. Deciding factors for effluent reuse by the industry include (1) availability of natural water, (2) quality and quantity of effluent, and cost of processing, (3) pumping and transport cost of effluent, and (4) industrial process water that does not involve public health considerations.
These ponds are used as the treatment units for reclamation of wastewater and thus reducing the load on scarce pure water resources.
How can Netsol Water help?
Netsol is India’s leading wastewater treatment solution company which covers all the needs of any water or wastewater treatment scheme on all levels. We have the expertise to provide wastewater solutions at domestic, industrial and municipal level.