Case Study: Compliant, Stable Effluent in Coking Plant

The application of BioRemove COD to a coking plant’s wastewater treatment system helped ensure compliance and stable effluent. 


  • Reduced Sludge Volume Index by 40%
  • Maintained COD removal efficiency despite 43.2% increase in influent COD


The treatment plant of a particular company’s coking branch operated under strict management and high environmental protection standards. Overall, the operation of the wastewater treatment system at the plant was good; however, the treatment plant hoped to further ensure compliant and stable effluent.

The secondary sedimentation tank effluent COD fluctuated greatly between 145-307 ppm, and large amounts of chemical flocculants had to be added to ensure effluent water quality.

effluent COD
Effluent COD of secondary sedimentation tank (click or tap to enlarge).


A bioaugmentation program was designed for the plant based on their specific situation, recommending BioRemove COD for a dosing period of 60 days. The goal of the program was to improve the biomass’ COD removal capabilities at higher loading rates, while improving floc structure to improve settling.



System data from May 1 to July 31 was analyzed to determine the effect of the bioaugmentation program on the system in reference to COD changes, sludge concentration changes, dilution water and flocculant reduction.


Over the course of the program, influent COD increased, due to an increase in influent volume after the bioaugmentation program began. The use of BioRemove COD maintained a relatively stable COD effluent under substantial increases in the influent loads.
 COD change curve

COD change curve (click or tap to enlarge).

After the bioaugmentation program, the system’s sludge activity improved significantly.


 bar graph 1
Comparison of MLVSS/MLSS (%) before and after bioaugmentation (click or tap to enlarge). 

Furthermore, bioaugmentation significantly improved sludge settling.

bar graph 2
                   SVI decrease indicates settling improvement (click or tap to enlarge).

Despite an increase in water flow during the program, the effluent COD remained stable, representing improved COD removal efficiency.

bar graph 3
                       Average influent and effluent COD, before and after bioaugmentation began (click or tap to enlarge).


 bar graph 4
Water volume before and after bioaugmentation began (click or tap to enlarge).

For multiple reasons, (oils, greases, filaments, poor settling, etc.), foam is a common problem for wastewater treatment in coking plants. After adding BioRemove COD, foam was significantly reduced due to improved settlement and overall reduction of oils and greases.    

 Before Bioaugmentation  After Bioaugmentation
figure 9 - foam prior to treatmentResized
figure 10 - foam after treatmentResized 



EnviroZyme’s biological program was easy to implement and provided significant benefits over alternatives, increasing COD removal efficiency. The use of BioRemove COD resulted in:
  • Improved plant efficiency
  • Simplified operations


About EnviroZyme

Headquartered in Bowling Green, Ohio, EnviroZyme is a world leader in the bioaugmentation industry. We leverage the power of naturally sustainable microbial solutions to effectively solve problems for people and the planet — without sacrificing quality or performance.

Our team of expert scientists and strategists collaborate to create, blend, and package custom and off-the-shelf microbial solutions for our clients. As a cGMP-compliant, ISO-certified, and FDA-registered facility, we’re proud to boast the quality, flexibility, and scale necessary for superior craftsmanship and innovation.

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