Hydrogen sulfide chlorination and turbidity control

Abstract

This study was conducted to identify the effects of hydrogen sulfide (H2S) chlorination on sulfur turbidity formation from a groundwater drinking source. The purpose of this research was to find the conditions under which chlorine would completely oxide H2S and limit the production of sulfur turbidity below 1 nephelometric turbidity unit (NTU). The study involved a series of laboratory batch tests using distilled water spiked with sodium sulfide then dosed with calcium hypochlorite. The parameters that were considered included the following: pH (3 to 10), chlorine to sulfide molar ratio (t, 2 and 4), reaction time (O.l to 24 hr), and dissolved oxygen content (anaerobic verses aerobic). The following parameters were observed: time, sulfide concentration, chlorine concentration, pH, oxidation reduction potential ( ORP) , turbidity, temperature, dissolved oxygen content (DO) . Similar experiments were conducted in the field using groundwater containing H2S from Pinellas County Keller I and II Water Treatment Plants. All parameters measured in the lab experiments were also monitored in the field experiments with the addition of trihalomethane formation potential (THMFP). For the field experiments, pH ranged from 6 to 8, chlorine to sulfide molar ratio ranged from 1 to 16 c12;s-2 , reaction time ranged from 0.1 to 24 hours, and DO was allowed to increase from anaerobic conditions to aerobic conditions. A log variant statistical model was developed by regression from the laboratory data that described turbidity as a function of five independent variables: H2s, pH, Cl2 dose, time to 30 minutes, and decreasing and increasing DO. The effect of Cl2 dose on turbidity formation was found to vary according to c12;s-2 molar ratio. Inconsistent turbidity production was observed at a molar ratio of 1 c12;s-2 ; maximum turbidity production was observed at a molar ratio of 2 c12;s-2 ; and less but consistent turbidity production was observed at a molar ratio of 4 c12;s-2 • The laboratory model could be used to describe turbidity at molar ratios of 2 to 4 c12;s-2 • This same model could be used in the field to describe turbidity production once complete H2S destruction or a Cl2 residual following 30 minutes of reaction is achieved from Cl2 doses or molar ratios greater than 4 c12;s-2 providing chlorine doses or molar ratios greater than 4 Cl2/ s-2 are modeled as a chlorine dose corresponding to a molar ratio of 4 c12;s-2 • These studies have shown that H2S is completely oxidized at a molar ratio of 2 c12;s-2 in distilled water. However, sulfur turbidity production during complete H2S chlorination occurred in all reaction conditions common to conventional water treatment. Sulfur turbidity formed in the lab by iii chlorination did not settle and was still present after 7 days. These studies also showed that chlorine reacted with H2S prior to reacting with organic precursors to produce THMFP.

Notes

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Graduation Date

1991

Semester

Summer

Advisor

Taylor, James S.

Degree

Master of Science (M.S.)

College

College of Engineering

Department

Electrical Engineering

Degree Program

Electrical Engineering

Format

PDF

Pages

160 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0029075

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

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