Secondary Treatment Research Paper

Secondary Treatment

4. Disinfection

5. Sludge Treatment

6. Tertiary Treatment

Preliminary Treatment At most plants preliminary treatment is used to protect pumping equipment and facilitate subsequent treatment processes. Preliminary devices are designed to remove or cut up the larger suspended and floating solids, to remove the heavy inorganic solids, and to remove excessive amounts of oils or greases. To affect the objectives of preliminary treatment, the following devices are commonly used:

1. Screens - rack, bar or fine 2. Commenting devices -- grinders, cutters, shredders 3. Grit chambers 4. Pre-aeration tanks

In addition to the above, chlorination may be used in preliminary treatment.

Septic tanks

2. Two story tanks -- Imhoff and several proprietary or patented units

3. Plain sedimentation tank with mechanical sludge removal

4. Upward flow clarifiers with mechanical sludge removal When chemicals are used, other auxiliary units are employed. These are:

1. Chemical feed units

2. Mixing devices

3. Flocculators

Secondary Treatment Secondary treatment depends primarily upon aerobic organisms which biochemically decompose the organic solids to inorganic or stable organic solids. The devices used in secondary treatment may be divided into four groups:

1. Trickling filters with secondary settling tanks

2. Activated sludge and modifications with final settling tanks

3. Intermittent sand filters

4. Stabilization ponds

Chlorination This is a method of treatment which has been employed for many purposes in all stages in wastewater treatment, and even prior to preliminary treatment. It involves the application of chlorine to the wastewater for the following purposes:

1. Disinfection or destruction of pathogenic organisms

2. Prevention of wastewater decomposition (a) Odour

RO is the point at which a weight is connected to the concentrated side of the layer compelling cleaned water into the weaken side, the rejected debasements from the concentrated side being washed away in the reject water. RO can likewise go about as a ultra filter expelling particles, for example, a few microorganisms that might be too huge to go through the pores of the membrane.

FIGURE 2

Electrodialysis

Electrodialysis is viable in expelling fluoride and nitrate from water. This procedure additionally utilizes layers in any case; coordinate electrical streams are utilized to pull in particles to the other side of the treatment chamber. This framework incorporates a wellspring of pressurized water, coordinate momentum control supply and a couple of particular films.

Electrodialysis Process

In this procedure, the films contiguous the influent steam are charged either decidedly or

Contrarily and this charge pulls in counter-particles around the film. These layers are intended to permit the positive or the negative charged particles to go through the layer, where the particles move from the item water stream through a layer to the two reject water streams. FIGURE