Chromium is used in the tanning process and is consequently present in the resulting effluent. A reduction in acceptable chromium levels from the water authority meant that action had to be taken with regards to site’s consent to discharge requirements. Chromium consent levels were to be reduced from 10mg/l to 5mg/l but the site had historical issues with levels as high as 92mg/l and was consistently struggling to be within consent at the current 10mg/l level.
Biochemica initially performed screening work through jar tests. There was no specific effluent treatment on site, but existing tanks were adapted to help treat the wastewater using the new Biochemica treatment programme.
The main aim of the treatment was to reduce chromium but Biochemica was also able to significantly reduce COD levels (soluble COD made up 30-50% of the total COD), as seen in Figure 1.
Figure 1 COD and TSS removal using Biochemica treatment
Improved the process performance through a better chemical programme as well as some minor process alterations, and yielded significant potential annual savings (Table 2).
Table 2 Chromium reduction seen in process after Biochemica process and chemistry changes
|Plant Samples||Chromium Reduction|
Benefits of Biochemica Solution:
- Significant potential annual savings through better COD and TSS reductions (this can be increased further by additional treatment)
- Biochemica designed, fabricated and installed equipment for treatment
- Ability to meet new chromium discharge consent level
- Maximised process efficiency through regular site service visits as part of solution offering