C. Clean electrochemical technology:
Using clean electrochemical technology, chemical oxygen demand, turbidity,
phenol, grease and petrochemicals as well as other hydrocarbon effluents are
removed by the combination of electro-flotation and electro-coagulation.
D. Advanced biodegradation using ozone and biological activated carbon:
For the growth of bio-film and degradation of bio-refractory, the pre-ozonation
and lifted moving bed biological activated carbon are used.
E. Coagulation-flocculation process:
It is used for specific petrochemical wastewater treatment containing high aromatic content (benzoic acid, phthalic acid, terephthalic acid), purified terephthalic
production unit wastewater, etc. In coagulation-flocculation process, some coagulants like ferric chloride and alum are used. The efficiency of this process is 75.5%
for removal of chemical oxygen demand. In this process, some cationic compounds
(polyacrylamide) are added to improve the sludge filtration. For better removal of
suspended solids, coagulation-flocculation process may be used for pre-treatment
prior to microfiltration and ultrafiltration membrane technologies (Ghimire and
Wang 2018).
8.4.6 Wastewater Treatment in Fertilizer Industry
The water effluent from the fertilizer industries contain nitrogenous, phosphorousbased fertilizers like urea, diammonium phosphate, isobutylidenediurea and
dicyandiamide which are hazardous. So, there is an urgent need to treat these
wastewaters before reuse. The effluent is accumulated in a holding tank and time
to time the level is recorded. The effluent is segregated based on the nature and
concentration of pollutants they contain. Suspended solids in effluents with minimum concentration of 100 mg/L should be combined together. Oil-based effluents
must be separated; also urea-bearing effluents should be separated from nitrogenbearing effluents. Highly acidic, alkaline effluents and ash slurry should be separated
from the rest of the effluent streams. The cooling tower purge water contains
chromate, phosphate and bioacids; hence, they should be segregated from the rest
of the effluents. Carbon-, arsenic- and cyanide-containing effluents should be stored
separately. These segregated effluents, however, can be combined, depending on
their properties and the type of treatment required, such that one can be utilized for
the treatment of the other. This type of judicious combination can reduce the
operating cost and increase the efficiency of the treatment process. Mainly two
types of processes are involved in fertilizer wastewater treatment plant; physicochemical and biological process (Sengupta 2019; Elela and Elkamah 1995).
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267
Using clean electrochemical technology, chemical oxygen demand, turbidity,
phenol, grease and petrochemicals as well as other hydrocarbon effluents are
removed by the combination of electro-flotation and electro-coagulation.
D. Advanced biodegradation using ozone and biological activated carbon:
For the growth of bio-film and degradation of bio-refractory, the pre-ozonation
and lifted moving bed biological activated carbon are used.
E. Coagulation-flocculation process:
It is used for specific petrochemical wastewater treatment containing high aromatic content (benzoic acid, phthalic acid, terephthalic acid), purified terephthalic
production unit wastewater, etc. In coagulation-flocculation process, some coagulants like ferric chloride and alum are used. The efficiency of this process is 75.5%
for removal of chemical oxygen demand. In this process, some cationic compounds
(polyacrylamide) are added to improve the sludge filtration. For better removal of
suspended solids, coagulation-flocculation process may be used for pre-treatment
prior to microfiltration and ultrafiltration membrane technologies (Ghimire and
Wang 2018).
8.4.6 Wastewater Treatment in Fertilizer Industry
The water effluent from the fertilizer industries contain nitrogenous, phosphorousbased fertilizers like urea, diammonium phosphate, isobutylidenediurea and
dicyandiamide which are hazardous. So, there is an urgent need to treat these
wastewaters before reuse. The effluent is accumulated in a holding tank and time
to time the level is recorded. The effluent is segregated based on the nature and
concentration of pollutants they contain. Suspended solids in effluents with minimum concentration of 100 mg/L should be combined together. Oil-based effluents
must be separated; also urea-bearing effluents should be separated from nitrogenbearing effluents. Highly acidic, alkaline effluents and ash slurry should be separated
from the rest of the effluent streams. The cooling tower purge water contains
chromate, phosphate and bioacids; hence, they should be segregated from the rest
of the effluents. Carbon-, arsenic- and cyanide-containing effluents should be stored
separately. These segregated effluents, however, can be combined, depending on
their properties and the type of treatment required, such that one can be utilized for
the treatment of the other. This type of judicious combination can reduce the
operating cost and increase the efficiency of the treatment process. Mainly two
types of processes are involved in fertilizer wastewater treatment plant; physicochemical and biological process (Sengupta 2019; Elela and Elkamah 1995).
8 Treatment of Petroleum Hydrocarbon Pollutants in Water
267