Date of Award
1-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
College/School
College of Science and Mathematics
Department/Program
Earth and Environmental Studies
Thesis Sponsor/Dissertation Chair/Project Chair
Yang Deng
Committee Member
Clement Alo
Committee Member
Huan Feng
Committee Member
Hussein I. Abdel-Shafy
Abstract
Water is vital to agriculture. In the United States, approximately two-thirds of freshwater withdrawal is consumed in the agricultural sector. Effective reuse of treated municipal wastewater offers a promising solution to mitigating dependence on scarce natural water resources and establishing a reliable, alternative, and local water supply, particularly in arid and semi-arid regions. Thus, the long-term goal of this dissertation is to develop innovative, technically viable, economically competitive, and environmentally friendly technologies for water reclamation to enhance agricultural sustainability and resilience. The overarching objective is to provide the scientific basis for utilizing ferrate(VI) to address diverse contaminants in municipal wastewater, bridge the gap between research and practical application of ferrate(VI) treatment, and ensure the long-term performance of ferrate(VI) applications for sustainable agricultural water reuse. Specifically, this dissertation research comprises four tasks that provide a comprehensive evaluation of the ferrate(VI)-based wastewater treatment process, highlighting its potential as an innovative and sustainable approach to water reclamation in agricultural irrigation. The major findings in each task are briefly summarized below. In task I, laboratory-scale experiments were carried out to comprehensively assess ferrate(VI) treatment of secondary municipal wastewater effluent for agricultural irrigation. The ferrate(VI)-enabled water reclamation was evaluated in four aspects. 1) Ferrate decomposition behaviors. Fe(VI) decay exhibited a biphasic kinetic pattern, that is, a 2nd-order reaction pattern with respect to Fe(VI) followed by a 1st-order reaction behavior. 2) Nutrient management. As the Fe(VI) dose increased, potassium (K) was linearly increased due to the presence of K in the ferrate(VI) salt (i.e., K2FeO4), total nitrogen (TN) nearly remained constant, and phosphorus (P), including P in both inorganic orthophosphate and organic phosphorus compounds, was largely removed. 3) Mitigation of emerging contaminants (ECs). Sulfamethoxazole, a representative EC, was effectively degraded over the ferrate(VI) treatment. 4) Disinfection and formation potential of disinfection byproducts (DBPs). Ferrate(VI) could not only effectively inactive waterborne pathogens, as indicated by the high removal of two bacterial indicators (i.e., total coliform and E. coli), but also mitigate the DBP precursors (e.g., trihalomethanes and 1,1-dichloroacetate) and thus reduce their formation potentials, to varying degrees, during subsequent chlorination. Task II focused on the investigation of the ferrate(VI)-mediated transformations of various N species within secondary effluent and revealed the underlying mechanisms. Although TN level remained nearly constant, ferrate(VI) altered the distribution of different N species. Specifically, ferrate(VI) oxidation could oxidize part of dissolved organic nitrogen (DON) into inorganic nitrogen (DIN), predominantly in the form of nitrate nitrogen (NO3--N). Among different DIN species, ammonia nitrogen remained almost the same, and nitrite nitrogen declined, while NO3--N increased. Ferrate(VI) oxidation closely resembles natural mineralization and nitrification steps, transforming less bio-accessible DON into bioavailable and soil-leachable NO3--N. This shift offers significant agricultural benefits, such as reducing the need for synthetic fertilizers and promoting environmental sustainability. Additionally, ferrate(VI) effectively mitigated the formation potentials of nitrogenous DBPs, such as haloacetonitriles, thereby minimizing the risks associated with harmful nitrogenous DBP formation during the following disinfection processes. In task III, efforts were made to examine the characteristics of ferrate(VI) treatment residuals and assess their potential for beneficial reuse as well as their ultimate disposal strategies. This task focused on two primary aspects. 1) Characterization. Ferrate(VI)-induced residual particles, primarily composed of iron (hydr)oxides with a mix of amorphous and crystalline phases, showed strong adsorption capacities in mitigating certain water contaminants, such as P and most toxic metals and metalloids. However, their small size, negative surface charge, and stable suspension in the supernatant posed a threat to downstream water treatment processes, particularly in achieving effective solid-liquid separation. The characteristics of these particles were influenced by operational parameters, such as Fe(VI) dose, pH, and sulfite activation. Higher Fe(VI) dose, elevated pH, and increased sulfite concentrations favored the formation of larger and denser particles, predominantly at the microparticle scale. 2) Management. The reuse potential of ferrate(VI)-induced iron sludge for P adsorption was limited due to the rapid saturation of adsorption sites, leading to a significant decline in P removal efficiency after the initial treatment cycle. Furthermore, this study highlighted the environmental risks associated with the disposal of these residuals. Under the study conditions, arsenic (As), chromium (Cr), lead (Pb), and selenium (Se) passed the Toxicity Characteristic Leaching Procedure (TCLP) tests, while cadmium (Cd) leaching exceeded its regulatory threshold. These TCLP results indicate that ferrate(VI) treatment residuals can be classified as non-hazardous waste in most cases, suitable for disposal in Subtitle D municipal solid waste landfills. However, when secondary municipal wastewater effluent contains significant levels of Cd, standard leaching tests must be carefully conducted. If Cd leaching fails these tests, the residuals are classified as hazardous waste under the Resource Conservation and Recovery Act (RCRA) and must be disposed of in Subtitle C hazardous waste landfills. In Task IV, the implications of this dissertation research and the limitations of ferrate(VI) technology for wastewater reuse in agriculture were discussed. This research makes significant contributions to advancing ferrate(VI) science and technology in two key areas (i.e., ferrate(VI)-mediated N transformation and ferrate(VI) treatment residuals management). These advancements enhance water and nutrient management practices in agriculture and provide a pathway for applying ferrate(VI) technology to address global water challenges in agriculture. Additionally, the major limitations of ferrate(VI) technology for water reclamation, such as challenges in P recovery, the need for pH adjustment, and the complexities associated with residuals management, were critically evaluated. These identified limitations help define the direction for future research efforts to overcome these barriers and broaden the practical application of ferrate(VI) technology. In summary, this dissertation establishes a solid scientific foundation of ferrate(VI)-enabled water reuse for agricultural irrigation, emphasizing its multifunctional capabilities in contaminant removal, nutrient recovery, and treatment byproduct management. This in-depth study advances the fundamental understanding of ferrate(VI) chemistry in secondary wastewater effluent, which underpins its application for agriculture reuse. These findings offer valuable insights for the development of efficient, promising, sustainable water treatment technologies capable of improving water quality and enhancing the resilience of agricultural systems against water scarcity and contamination challenges. Furthermore, this study underscores the importance of integrating environmentally sound strategies for managing ferrate(VI)-induced residuals, addressing both regulatory and ecological considerations. These contributions are pivotal for advancing sustainable agricultural practices, supporting the transition to a circular water economy, and mitigating the broader environmental risks associated with wastewater reuse and residual waste management.
File Format
Recommended Citation
Lin, Qiufeng, "Ferrate(VI)-Enabled Water Reuse for Agricultural Irrigation" (2025). Theses, Dissertations and Culminating Projects. 1502.
https://digitalcommons.montclair.edu/etd/1502
