| Abstract |
Iron-rich ferric hydroxide desulfurized waste (FHDW) supports biological denitrification.In a batch test, using FHDW as electron donor, 100% NO3- removal efficiency was achieved.The FHDW-based denitrification produced alkalinity.Use of FHDW as the electron donor reduce landfill expenses, and mitigate environmental pollution.FHDW has a high potential to function as an attractive electron donor for treating nitrogenous waste. PurposeThis study aimed to investigate the feasibility of using iron-rich ferric hydroxide desulfurized waste (FHDW) as an alternative electron donor for biological denitrification, with the objective of diverting it from landfill disposal. By harnessing the potential of the FHDW as the electron donor, we can effectively offset landfill costs while simultaneously mitigating environmental pollution.MethodsBatch and lab-scale up-flow column tests were conducted. The batch experiment was conducted in a 500 mL media bottle, using 200 mL FHDW and 250 mL synthetic wastewater. For the column test, two plastic reactors having an internal diameter of 3.8 cm and a height of 21 cm were established. Column I was filled with FHDW (240 mL), and column II with S0 (240 mL), and operated at different empty bed contact times (EBCTs).ResultsBoth the batch and column test results confirmed the possibility of using FHDW as an electron donor for biological denitrification. The batch test achieved 100% nitrogen removal in 5 days of operation. The highest denitrification activity was observed in column I, achieving 100% nitrate reduction at 16 and 8 h EBCTs, and the denitrification activity reduced significantly as the EBCT shortened. Column II exhibited the lowest denitrification performance compared to the FHDW-based denitrification system. The FHDW-based denitrification system produced alkalinity so no buffer addition was needed.ConclusionsThis study confirmed the feasibility of using FHDW as an electron donor in a biological denitrification system. Utilizing desulfurized waste as an electron donor, we can achieve the dual benefit of alleviating financial burdens associated with landfilling and reducing environmental pollution. Elemental sulfur (S0)-based denitrification is an elegant and cost-effective biological method for removing nitrate (NO3-) from wastewater. However, acidity and the requirement for adding buffering reagents are the primary factors limiting the acceptance of an S0-based autotrophic denitrification (ADN) process. In recent years, pyrite (FeS2) has been developed as a prospective substrate for ADN as a pyrite-based denitrification system generates less acidity than an S0-based denitrification system. This study aimed to utilize iron-rich ferric hydroxide desulfurized waste (FHDW) pellets as an electron donor for biological denitrification. The results of this paper indicated that waste materials (FHDW) had good removal efficiency towards NO3--N. The novelty of this study lies in the fact that it aims to utilize desulfurized waste as an electron donor for biological denitrification diverting from the conventional practice of landfilling such waste. Utilizing desulfurized waste as an electron donor, we can achieve the dual benefit of alleviating financial burdens associated with landfilling and reducing environmental pollution. Thus, this study provides a novel approach toward a cost-effective and eco-friendly solution, aiming to prevent pollution and promote a circular economy. |
