Page 554 - Industrial Wastewater Treatment, Recycling and Reuse

524 Industrial Wastewater Treatment, Recycling, and Reuse

for treated water. In general, industrial wastewater treatment requires a large
amount of chemicals, multiple operations and designs, a fairly high degree of
process control, and regular maintenance. In fact, in many plants mainte-
nance has been such a serious issue that effluent treatment plants fail to oper-
ate as per the desired standards or have to close down. Stringent pollution
control norms require maintaining complex systems that are difficult to
oversee and thus require trained operators, especially for the maintenance
and operation of biological treatments (anaerobic systems, in particular).
This complexity also leads to an escalating cost of treatment.
As a rule of thumb, complex effluent treatment plants designed for
industrial wastewater treatment, recycling, and reuse are difficult to operate
and hard to maintain, and, as a result, these plants are cost intensive in terms
of plant space, equipment, and labor. For smaller chemical process industries,
an effluent treatment plant also tends to require more space than a
manufacturing plant does. Therefore, in developing countries, common
effluent treatment plant (CETP) facilities have been provided for facilitating
the treatment of combined effluent from various industries. However, an
intelligent combination of centralized and decentralized wastewater treat-
ment facilities (decentralized: collection, treatment, and recycling or reuse
of wastewater at or near the source of generation) can significantly aid
not only in cost reduction and increased effectiveness, but also in apt use
of water recycling and reuse.
Contemporary economic development has also led to the growth of
many water intensive industries that tend to represent the most water-
polluting sectors of the economy. The most notable examples of these indus-
tries include the iron and steel industry (mainly cooling water contaminated
with pollutants such as ammonia; cyanide; complex polycyclic aromatic
hydrocarbons such as benzene, phenols, cresols; acids; salts; and oil); the
mining industry (high volumes of water containing fine particulates, metals,
surfactants, and oils); the chemical, petroleum, and fertilizer industries
(medium to large volumes of water containing a variety of organic com-
pounds, oil, pesticides, dyes, and solvents); the dye and textile industry
(medium volumes of water containing reactive and nonreactive dyes and
many refractory pollutants that are difficult to degrade); the pulp and paper
industry (large volumes of water containing organics, chlorinated com-
pounds, color, and Biological Oxygen Demand [BOD]); the distillery
industry (medium-high volumes of water containing high BOD, Chemical
Oxygen Demand [COD], color, and organics); and the food and dairy