Date of Award

5-2022

Document Type

Thesis

Degree Name

Master of Science in Environmental Sciences

Department

Chemistry and Biochemistry

First Reader/Committee Chair

Stanley, Brett

Abstract

Total Dissolved Solids (TDS) are primarily inorganic salts that can pass through a 2-micron (or smaller) filter and, when found in high concentrations, can cause adverse effects on aquatic organisms and the surrounding environment. The agency servicing Lake Elsinore and surrounding areas is the Elsinore Valley Municipal Water District (EVMWD). EVMWD’s wastewater treatment facilities are not equipped to remove TDS from the wastewater. Therefore, the influent TDS values are often similar to the final treated effluent recycled water TDS values. EVMWD has permit limits at the wastewater treatment plants relating to TDS, and due to the higher influent TDS concentrations noted at the wastewater treatment facilities, the effluent TDS values regular exceed these permit limitations. This analysis investigated whether the cause of the increased TDS values is from the following: the source water itself; the chemical treatment of potable source water for disinfection; regular use of water at homes, businesses, and industries and associated conservation measures; or chemical addition at wastewater sewage lift stations for odor control.

Approximately 600 samples were collected at various locations from Lake Elsinore and the surrounding region for this analysis. The raw source water TDS was not identified as being a key contributor to the variation of the influent TDS values; however, it was identified as comprising the majority of the increased TDS mass loadings for the three facilities measured. The linear regression analyses yielded coefficients of determination which indicated that consumer uses, including industrial, commercial, and domestic users, along with associated conservation practices and lift station chemical additions, were strongly correlated with influent values at two Water Reclamation Facilities (WRF): the Railroad WRF and Horsethief WRF. The analysis showed minor impact regarding the addition of chemicals to potable water for disinfection purposes as a contributor to all three facilities. Therefore, the analysis suggests that the TDS increase as a result of addition of chemicals is secondary to the increase caused by source water TDS, consumer usage, and conservation measures. However, more analyses and studies should be done to refine the quantification of TDS contribution from various sources to recommend appropriate control measures and assist in compliance with the permit limitations.

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