Cyanide Thiocyanate and phenol removal from wastewater in steel plant by BactaServe bacterial culture

1. Background: -

In the steel industry, toxic materials like Cyanide, Thiocyanate and Phenol are produced in industrial processes during the production of coke. This steel plant is located in the eastern part of India. It is one of the largest manufacturers of Plate Mill plates, HR plates and coils, ERW pipes, SW pipes, CR sheets and coils, Galvanised sheets (GP & GC), and silicon steel sheets.

1.1 Plant Specifications: -

The capacity of this ETP is 3600 m3/day, having two aeration tanks in series along with pre-anoxic and post-anoxic tanks followed by a membrane bioreactor. ETP-treated effluent is then fed to R.O. for effluent recycling.

1.1.1 Process Flow Diagram: -

2. Challenges: -

The coke manufacturing process generates cyanide and thiocyanate which comes in the effluent. Cyanide at 6.5 ppm is a toxic molecule that requires adequate safety measures for 100% degradation. Thiocyanate at 350 ppm is relatively more stable than cyanide, requiring a higher degree of biodegradation efficiency. Phenol at 250 ppm also is a big challenge. NH3-N at 300 ppm further increases to 400 ppm after bacterial action on the thiocyanate molecule. Stage-2 NH3-N and subsequent denitrification requires 2 stages of bacterial anoxic denitrification.

Table 1: Inlet parameters- Routine.

Table 2: Inlet parameters- Critical.

3. Special Technical Solution: -

As a solution, we dosed BactaServe Aerobic along with special strains of paracoccus and pseudomonas species for the removal of cyanide and thiocyanate. Pseudomonas species worked exceptionally well for phenol reduction from 250 ppm to 2.5 ppm.

Table 3: Bacterial cultures required over 45 davs period.

For the degradation to occur, we have provided them with a Bioculture dosing protocol as below:

Table 4: Dosing protocol.

BactaServe nutrient removal containing nitrifiers ensures the conversion of 400 ppm NH3- N to nitrates. The De-nitrifiers in an anoxic tank convert the N03-N to N2 gas.

3.1 Photographic presentation of site performance: -

3.2 Graphical Presentation of Parameters: -

4. Executive Summary: -

This assignment presented us with challenges like high inlet COD, Cyanide, Thiocyanate, Phenols, and NH3-N. Low inlet BOD further complicated the situation. BactaServe Bioculture could solve the issue since it was incorporated with specific bacterial strains which were pre-acclimatized for cyanide, Thiocyanate, Phenol, and NH3-N degradation.

A tailor-made Bioculture of Amalgam Biotech could only solve this with the help of our indigenous strain bank.