Page 545 - Industrial Wastewater Treatment, Recycling and Reuse

Zero Liquid Discharge Solutions 515

13.5.2.3 Concluding Remarks
The textile industry in India faces environmental issues due to color and
nonusable high TDS brine solutions present in its effluent. The major issue
for plant operation is the mixed salts coming out of the evaporator systems, as
those salts cannot be reused in the dyeing process. The present technique
represents a unique solution for the selective crystallization and recovery
of Glauber’s salt followed by mixed salts, which can then be reused in the
dyeing process. The recovery and reuse of salts results in handsome paybacks
for the evaporation system.

13.5.3 Case Study 3: Innovative Wastewater Treatment
solutions for Chemicals and Fertilizers Industry

In this particular case, effluent is from Fertilizer industry. The effluent is rich
in Ammonical Nitrogen content hence it was not feasible to treat it biolog-
ically. Thus, the scheme recommended was steam stripping of Ammonia
followed by Sequential Batch Reactor for COD & BOD reduction.
Client: chemicals and fertilizers industry
Scheme offered:
Ammonia stripper+2 stage sequential batch reactor (SBR)+tertiary
treatment
(PSF+ACF)
3
Capacity: 600 m /day.

13.5.3.1 Process Description
13.5.3.1.1 Equalization
The effluents from all industrial streams is collected in an EQT and pro-
vided adequate retention time. Jet mixing encourages flow and character-
istics equalization. The pH of the effluent is also adjusted to 11.5 in this
tank. The EQT is housed in a shed with a vent for the release of
excess gases.

13.5.3.1.2 Online NaOH Dosing System Before Stripper
An online alkali dosing system with auto control is provided to increase the
pH of effluent before it passes into the ammonia stripper.

13.5.3.1.3 ECOFINE Ammonia Stripper
The “ECOFINE” ammonia stripper is designed to remove excess ammonia
from the effluent before it is sent to aerobic biological treatment.