Biological Wastewater Treatment System

Biological wastewater treatment is now used extensively with many modifications to stabilize dissolved biodegradable organic matter that are present in wastewater. Biological wastewater treatment system also popularly called as activated sludge process is utilized by most of the industries for removing dissolved organic matter (DOM). Whole system requires less space and functions optimally to yield best results.

 

The parameters on which the the biological wastewater treatment can be judged are:

 

Constituents of Biological Wastewater Treatment
There are two main constituents of biological wastewater treatment plant which are as follows:

(a.) Activated Sludge Process
This process is employed commonly. In this process, floc in the tank is supplied with oxygen. The oxygen supplied in such a way that maximum contact between the incoming wastewater and the organism in the floc is made. For suspended solids including colloidal materials, activated sludge has high affinity.
(b.)Trickling Filter Process
In trickling filter process, unlike the activated sludge process, the microorganism are attached to fixed bed rather than floating and suspended. Wastewater is distributed over a bed supporting the biological film through rotary nozzle.

 

Factors affecting the working of biological wastewater treatment
Biological wasterwater treatment or the activated sludge process depend on the following factors:

 

Temperature
The metabolic activity of the microorganism may change if they are subjected to a temperature change as they adapt themselves to the temperature change. It is therefore necessary to maintain the temperature of wastewater between 28°C to 30°C for effective performance. If the temperature of the water rises by two degrees, the dissolved oxygen solubility reduces by approximately 4%.

 

Dissolved Oxygen

Dissolved oxygen (DO), is essential for aerobic biological treatment process. The D.O level should be kept around 0.5 ppm in aeration tank. This level can be maintained by maintaining 2.0 ppm of D.O in the effluent that flows from the aeration tank. For denitrification in the returned bio-sludge, atleast 0.2 ppm of D.O should be maintained in the clarification system. In the absence of D.O, the efficiency of solid separation may be affected in the secondary clarifications.

 

Cow-Dung for Biological Treatment Process
Cow dung consist of lignin's cellulose and E-Coli bacteria. E-Coli has little use in aerobic degradation of wastewater. These materials are more effective in anaerobic treatment process.

 

pH and Toxic Conditions
Major changes in the pH can effect the plant performance as bacteria survives well 5.5 to 9.0 pH and thrive in 6.5 to 8.5 pH.
Excessive presence of toxic materials like; cyanides, heavy metals, high TDS and FRC may slow down the plant performance.

 

Nutrients
Biological environment is kept healthy by the nutrients. If there is surge of shock organic loads into the aerobic biological treatment system then it is necessary to add additional nutrients in order to keep the microorganism healthy and active.
Looking at the water scarcity it is imperative to adopt advanced and cost effective technology in wastewater treatment which will allow the industry to remain functional in continuously changing environment scenario.

Tags:- Biological Wastewater Treatment Process

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