Process Equipment
- 1. Basic Engineering and Design
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Wastewater treatment equipment is used to treat, remediate, and process effluent wastewater.
By definition, wastewater carries a mixture of dissolved or suspended solids from residences, agriculture, and industries.
Some wastewater is polluted, meaning that industrial wastes, chemicals,
toxins, or other objectionable materials are present in sufficient
quantities to cause a measurable degradation of water quality.
Often, wastewater treatment equipment is used at sewage treatment plants,
facilities that use a series of tanks, screens, filters, and other processes to remove dissolved and suspended solids from wastewater.
Wastewater treatment equipment may also be used commercially, typically in
conjunction with aboveground or sub-surface systems such sewers, disposal wells, and waste ponds.
Widely used terminology refers to four levels of wastewater treatment:
primary, secondary, tertiary (or advanced), and disinfection.
1-1 Primary (mechanical) treatment is designed to remove gross, suspended and floating solids from raw sewage.
It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids.
This level is sometimes referred to as ˇ°mechanical treatmentˇ±,
although chemicals are often used to accelerate the sedimentation process.
Primary treatment can reduce the BOD of the incoming wastewater by 20-30% and the total
suspended solids by some 50-60%. Primary treatment is usually the first stage of wastewater treatment.
Many advanced wastewater treatment plants in industrialized countries have started with primary treatment,
and have then added other treatment stages as wastewater load has grown,
as the need for treatment has increased, and as resources have become available.
1-2 Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment.
This is achieved by microbes consuming the organic matter as food,
and converting it to carbon dioxide, water, and energy for their own growth and reproduction.
The biological process is then followed by additional settling tanks (ˇ°secondary sedimentation", see photo)
to remove more of the suspended solids. About 85% of the suspended solids and BOD can be removed
by a well running plant with secondary treatment. Secondary treatment technologies include the basic
activated sludge process, the variants of pond and constructed wetland systems, trickling
filters and other forms of treatment which use biological activity to break down organic matter.
1-3 Tertiary treatment is simply additional treatment beyond secondary!
Tertiary treatment can remove more than 99 percent of all the impurities from sewage,
producing an effluent of almost drinking-water quality. The related technology can be very expensive,
requiring a high level of technical know-how and well trained treatment plant operators,
a steady energy supply, and chemicals and specific equipment which may not be readily available.
An example of a typical tertiary treatment process is the modification of a conventional
secondary treatment plant to remove additional phosphorus and nitrogen.
1-4 Disinfection, typically with chlorine, can be the final step before discharge of the effluent.
However, some environmental authorities are concerned that chlorine residuals in the effluent can be a problem
in their own right, and have moved away from this process. Disinfection is frequently built into treatment plant design,
but not effectively practiced, because of the high cost of chlorine, or the reduced
effectiveness of ultraviolet radiation where the water is not sufficiently clear or free of particles.
As a wastewater treatment sector, · Packaged Plants for Sewage pre-treatment
· Packaged Plants for biological wastewater treatment using M.B.B.R.- IFAS technology
· MF/UF membrane technology (MBR)
· Packaged Plants for tertiary treatment using MF/UF membrane systems
- 2. Water Treatment Equipment Sector
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· Packaged Plantsˇ± for potable water treatment using Ultra Filtration technologies
· Conventional clarification and media filtration technologies
· RO
