Graduation Year

2024

Document Type

Thesis

Degree

M.S.E.V.

Degree Name

MS in Environmental Engr. (M.S.E.V.)

Degree Granting Department

Civil and Environmental Engineering

Major Professor

James Mihelcic, Ph.D.

Committee Member

Sarina Ergas, Ph.D.

Committee Member

Andres Tejeda, Ph.D.

Keywords

water reuse, reclamation, food security, fertilizer, nutrient management

Abstract

Wastewater stabilization ponds, such as facultative and maturation lagoons, have been shown to be effective processes to manage conventional water quality parameters found in domestic wastewater. The main goal of this thesis is to explore whether wastewater stabilization ponds can simultaneously reduce pathogens to safe levels while supporting agricultural activities through nutrient recovery. A large dataset for water quality of wastewater lagoon effluent in the U.S. was obtained at the state level and combined into regional southern and northern locations. Analysis of data showed there was significant difference in lagoon effluent concentration between northern and southern states for the water quality parameters ammonia, total phosphorus, fecal coliforms, and E. coli. The result for ammonia was surprising because southern states are typically expected to have higher lagoon temperatures, which will increase the rate of nitrification Possible explanations for this discrepancy are that southern states may have less effective hydraulic design and less stringent discharge permit requirements. In northern states, higher concentrations of coliform and E. coli were noted in lagoon effluent, which was attributed to the lower levels of solar radiation in this region. No significant difference was found for regional differences in total nitrogen effluent concentration. Additionally, a correlation analysis showed a negative correlation with flow rate and total nitrogen and total phosphorus in a lagoon effluent (i.e., as flow rate increases, total nitrogen and phosphorus concentration in the lagoon effluent decreases). It was estimated that the areal loading of nitrogen and phosphorus embedded in lagoon effluent could be well below the potential for forage and crops to uptake nitrogen and phosphorus; thus, showing the potential for gaining value from wastewater lagoon effluent to support forage and crop production. However, datasets only contained information on the presence of fecal indicators in treated effluent and were found to be lacking in information on the presence (or absence) of specific pathogens. Therefore, even though some case studies are available to support the thesis objective, no conclusion could be made on a large regional basis on whether the effluent could be safely applied to support agricultural activity in the case of reducing risk associated with specific pathogens.

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