Biological Denitrification As A Remediation Option For High Nitrate Industrial Effluent From Sable Chemical Industries Using Raw Municipal Sewage
- Author
- Tendai Govere
- Title
- Biological Denitrification As A Remediation Option For High Nitrate Industrial Effluent From Sable Chemical Industries Using Raw Municipal Sewage
- Abstract
- In Zimbabwe, industrial effluent, notably from processes at the Sable Chemical factory has been found to contain excessive nitrate levels and that these present a major environmental and health challenge. The project’s objective is to assess the potential of biological denitrification as a viable remediation strategy for high nitrate effluent from Sable Chemicals using raw municipal sewage as an organic carbon source, promoting bacterial growth and activity essential for efficient denitrification. The study found that using raw municipal sewage as carbon source effectively removed nitrates from industrial effluent with ethanol and hydrazine enhancing the process, offering a sustainable and cost-effective solution for wastewater treatments and reducing environmental pollution. The study was initiated by determining the initial nitrate content in the effluent from Sable Chemicals by use of ultraviolet spectrometer, to act as ground zero for treatment efficacy monitoring as well as the physico-chemical characteristics of Kwekwe Municipality. Nitrates were high in all sampling points and the BOD from Kwekwe sewage was way above the legal limit. Sable process effluent, sampled from different sites (dam1 dam 2 dam 3) rich in nitrate was inoculated with various sewer treatments, including returning activated sludge, BNR liquor, and raw sewer. They were maintained under anaerobic conditions. Where effluent was inoculated with sewage, some samples were infused with distilled water to enable comparison. Other experimental treatments were conducted, including adding hydrazine as an oxygen scavenger to the sewage inoculum and adding an external carbon source as 5% ethanol, to assess the rate of denitrification. The amount of nitrates in the batch tests where sewer was infected decreased overall. The rate of removal for BNR returned activated sludge and raw sewage were 67%, 77% and 74% respectively, for a period of 16 days. In an experiment with distilled water the nitrate removal was 27%. Nitrate levels lowered from 90 mg/L to 23 mg/L overall in 16 days. Average amount of nitrate removal in all treatments was 3.7mg/L per day. During a ten-day timeframe, batch test inoculated with hydrazine and ethanol showed a 60% and 64% drop in nitrate-nitrogen. The results of the experiment demonstrated that total nitrogen in Sable effluent may be reduced or removed through denitrification using municipal sewage effluent as a bioremediation medium and shift from the red band of their effluent disposal license to a lower and less expensive band,
- Date
- June 2024
- Publisher
- BUSE
- Keywords
- Denitrification
- Sable Chemical Industries
- Municipal Sewage
- Supervisor
- Mr. D Dzvene
- Item sets
- Department of Environmental Sciences
- Media
-
Govere - SHEM.pdf