Page 546 - Industrial Wastewater Treatment, Recycling and Reuse

516 Industrial Wastewater Treatment, Recycling, and Reuse

Raw water effluent, which contains around 2000 ppm of ammonia and
VOCs (Volatile Organic Compounds), enters the ammonia stripper plant at
11.5 pH. The feed is preheated in a heat exchanger, using column bottom
stream. This preheated stream is then fed to the stripper.
Low pressure steam is supplied to the ammonia stripper reboiler for use as
a heating medium. Vapors coming out of the stripper column contain mostly
water with ammonia and other VOCs, which are then partially condensed in
3
the stripper condenser. During the process, around 40–45 m /day of steam
condensate will be generated via stripping.
The condensed stream is recycled back to the column, and the remain-
ing vapors (emissions) are sent to the existing incinerator system or flare
unit. The treated water from the stripper column is subsequently cooled
in the shell and tube heat exchanger before being sent for further
treatment.
The ammonia stripping plant is designed as a skid-mounted unit, so that
the plant can be transported in state with all parts assembled, painted, and
erected. The total plant package involves small skid-mounted units to be
assembled on site. The structural material requirements are based on Indian
industry standards, however. Thus, the design for the structure complies
with such standards, and all static equipment, pressure vessels, pumps, and
heat exchangers are erected on the skid.
Pipes and fittings are also mounted on the skid and meet ANSI standards.
• Steam is supplied through the reboiler for higher condensate recycling.

• Raw effluent at 30 C is first heated with the help of hot treated water
taken from the column bottom using the heat exchanger.
• Hot raw effluent from the heat exchanger is fed to the top of the column
for ammonia stripping.
• Cold treated water is available from the heat exchanger outlet for further
treatment.

13.5.3.1.3.1 Benefits of ECOFINE—Ammonia Stripper Plant
• Optimal heat usage to conserve energy
• Well-engineered plants with high efficiency trays to ensure elaborate
separation
• Proper care in the design of calming zone on trays, the large area of
down-comers, gas-liquid separators with tangential entry, and vapor
bottles. (This design ensures proper gas-liquid disengagement and elim-
inates risk of liquid carryover.)