Human exposure to hydrogen sulphide concentrations near wastewater treatment plants

Odours from wastewater treatment plants are comprised of a mixture of various gases with hydrogen sulphide (H2S) often being the dominant constituent. Activated sludge diffusion (ASD) as a biotreatment system for odour abatement has been conducted for over 30 years but has limited broad application due to disagreement in the literature regarding the effect that ASD may have on wastewater treatment performance. The effects of continuous H2S diffusion at 25 ppmv, with weekly peaks of approximately 100 ppmv, on H2S removal efficiency and wastewater treatment performance was evaluated over a 2-month period using an activated sludge pilot plant. H2S removal averaged 100% during diffusion at 25 ppmv, and 98.9% during the 100 ppmv peak periods. A significant increase in mixed liquor volatile suspended solids concentration (P < 0.01) was observed during H2S diffusion, which may be due to an increase in H2S-degrading microorganisms. There was no adverse effect of H2S on nitrification throughout the ASD trials. Ammonia (NH3) removal was slightly better in the test receiving H2S diffusion (87.6%) than in the control (85.4%). H2S diffusion appeared to improve robustness of the AS biomass to operational upsets.

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Ferric chloride for odour control: studies from wastewater treatment plants in India

Water Practice & Technology ◽

10.2166/wpt.2020.111 ◽

2020 ◽

Author(s):

T. C. Prathna ◽

Ankit Srivastava

Keyword(s):

Wastewater Treatment ◽

Ferric Chloride ◽

Hydrogen Sulphide ◽

Wastewater Treatment Plants ◽

Chloride Concentration ◽

Oxygen Demand ◽

Cost Effective ◽

Odour Control ◽

Pre Treatment ◽

Wastewater Samples

Abstract This study was about the feasibility of using ferric chloride as an agent for odour control in wastewater treatment plants (WWTPs) due to hydrogen sulphide emission. Total inlet sulphide concentrations at 11 WWTPs in Delhi were measured and ranged between 1.1 and 14.8 mg/L. Wastewater samples from Najafgarh drain were used in jar tests to estimate the ferric chloride concentration required to obtain acceptable treatment. Ferric chloride was effective in removing sulphide, phosphate and total suspended solids (TSS), and gave significant biological oxygen demand (BOD) reduction. It was ineffective, however, in removing ammoniacal-nitrogen. A dose of 40 mg/L removed 76% of total sulphide, which corresponds to a significant reduction in hydrogen sulphide emission. The study demonstrated that ferric chloride can be used as a cost-effective pre-treatment step in WWTPs to reduce sulphur-related odours significantly, as well as TSS, BOD and phosphate from wastewater.

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Analysis and balance of phosphorous removal from wastewater at urban wastewater treatment plant

Pollack Periodica ◽

10.1556/606.2020.15.2.13 ◽

2020 ◽

Vol 15 (2) ◽

pp. 142-151

Author(s):

Peter Lukac ◽

Lubos Jurik

Keyword(s):

Wastewater Treatment ◽

Wastewater Treatment Plant ◽

Wastewater Treatment Plants ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Phosphorus Recovery ◽

Anaerobic Sludge ◽

Biological Phosphorus Removal ◽

The Mean

Abstract:Phosphorus is a major substance that is needed especially for agricultural production or for the industry. At the same time it is an important component of wastewater. At present, the waste management priority is recycling and this requirement is also transferred to wastewater treatment plants. Substances in wastewater can be recovered and utilized. In Europe (in Germany and Austria already legally binding), access to phosphorus-containing sewage treatment is changing. This paper dealt with the issue of phosphorus on the sewage treatment plant in Nitra. There are several industrial areas in Nitra where record major producers in phosphorus production in sewage. The new wastewater treatment plant is built as a mechanicalbiological wastewater treatment plant with simultaneous nitrification and denitrification, sludge regeneration, an anaerobic zone for biological phosphorus removal at the beginning of the process and chemical phosphorus precipitation. The sludge management is anaerobic sludge stabilization with heating and mechanical dewatering of stabilized sludge and gas management. The aim of the work was to document the phosphorus balance in all parts of the wastewater treatment plant - from the inflow of raw water to the outflow of purified water and the production of excess sludge. Balancing quantities in the wastewater treatment plant treatment processes provide information where efficient phosphorus recovery could be possible. The mean daily value of P tot is approximately 122.3 kg/day of these two sources. The mean daily value of P tot is approximately 122.3 kg/day of these two sources. There are also two outflows - drainage of cleaned water to the recipient - the river Nitra - 9.9 kg Ptot/day and Ptot content in sewage sludge - about 120.3 kg Ptot/day - total 130.2 kg Ptot/day.

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