Wastewater Treatment Plant Design Project

Project Description:

Wastewater collection is done in many steps, some common steps are the collection of wastewater that is mainly done by the municipal administration. It is done channel technique and water is made to flow in channels to one central point. This water is then directed to a treatment plant using underground systems. Another important factor is the odor control as wastewater contains a lot of dirty substances with foul smell over time. All the odor sources are contained and neutralized using chemicals.
1. Design Parameters:
The overall design of the wastewater treatment plant consists of 4 stages: i) Primary treatment which consists of screening, grit removal and sedimentation ii) Secondary treatment consists of a bioreactor iii) Tertiary treatment consists of nitrogen removal, adsorption and pH control.
2. Screening:
Screens typically consist of wedge wire. It is carried out in two phases. In the 1st phase also called coarse screening, the size of the opening is 20-30 mm. It captures the large objects. In the second phase called fine screening, the openings vary between 1.5 to 6.4 mm. Cross section area of the screens is typically 1 msq.
3. Primary Sedimentation:
Sedimentation is the process of removing solid particles heavier than water by gravity settling. In wastewater treatment, sedimentation is used to remove both inorganic and organic materials which are settleable in continuous-flow conditions. The sedimentation tank consists of a tank with 2 settling funnels where solid waste settles down. Baffles are provided to enhance the settling process. The wastes removed in this stage 20 kg/h for a 1000 kg/h feed.
4. Sand Bed Bioreactor:
A bioreactor packed with sand of effective particle size 0.3-0.5 mm. The uniformity coefficient (a measure of similarity of shape and size in sand particles) of sand is 4. Assuming 30% BOD is removed by sedimentation, about 92% BOD removal takes place in this reactor.
5. Nitrogen and Phosphorus removal:
6. For nitrogen removal, a Step Feed Anoxic Aerobic Process is used. In this process, wastewater is introduced at several feed points. Phosphate release and denitrification take place in the anoxic zone. In the aerobic zone, nitrification and BOD removal takes place.

7. Sludge Digestion:
Sludge digestion involves the treatment of highly concentrated organic wastes in the absence of oxygen by anaerobic bacteria. The dried sludge is fed to a cylindrical RCC tank of 6m diameter and the height of sludge in the tank is 6m.
8. pH Control Unit:
The water discharged to the streams should neither be highly acidic nor alkaline. The acceptable discharge pH of 6:5. The pH of water in the tank is measured, which serves as an input to a controller. If pH is not close to 6.5, the exit stream is shut off.

• Wastewater
• Bioreactor

• Wastewater
• Bioreactor