WASTEWATER TREATMENT prepared by Mrs Ancy

STEPS IN WASTEWATER TREATMENT

1.    SCREENING AND PUMPING
The incoming wastewater passes through screening equipment where objects such as rags, wood fragments, plastics, and grease are removed. The material removed is washed and pressed and disposed of in a landfill. The screened wastewater is then pumped to the next step: grit removal.

2.    GRIT REMOVAL
Grit settles by gravity into the bottom of the tank (in a grit hopper) while effluent exits at the top of the tank. The grit that settles into the grit hopper may be removed by a grit pump or an airlift pump. A detritus tank (or square tank degritter) is a constant-level, short-detention settling tank.

3.    PRIMARY SETTLING.
Primary settling is the process by which the velocity of the sewage is reduced below the point at which it can transport the suspended matter, so that much of this settles and can be removed as sludge.

4.    AERATION / ACTIVATED SLUDGE.
Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater. ... After settling in a separate settling tank, bacteria forming the "activated sludge" flocks are continually recirculated back to the aeration basin to increase the rate of decomposition.
 
5.    SECONDARY SETTLING.
Secondary settling is the final step of the activated sludge-based biological wastewater treatment. Secondary settling tanks (SSTs) are therefore an essential unit of producing a clear effluent.

6.    FILTRATION
Filtration is a physical, biological, or chemical operation that separates solid matter and fluid from a mixture with a filter medium that has a complex structure through which only the fluid can pass.

 
7.    DISINFECTION
Killing, removal, or deactivation of harmful microorganisms can be referred to as disinfection. Destruction or deactivation of pathogenic microorganisms results in stopping their reproduction and growth. People may fall ill by consuming the contaminated water containing the pathogenic microorganisms.

8.    OXYGEN UPTAKE
Aerobic capacity is commonly described by the o₂max, or maximal oxygen uptake. This measurement is an indication of (1) the ability of the cardiovascular system to provide oxygen to working muscles and (2) the ability of those muscles to extract oxygen for energy generation in the form of adenosine triphosphate (ATP).