Degradation of Landfill Leachate Using UV-TiO2 Photocatalysis Combination with Aged Waste Reactors

Abstract

This study explored the performance of TiO2 nanoparticles in combination with aged waste reactors to treat landfill leachate. The optimum conditions for synthesis of TiO2 were determined by a series of characterizations and removal rates of methyl orange. The effect of the ultraviolet irradiation time, amount of the catalyst, and pH on the removal efficiency for the chemical oxygen demand (COD) and color in the leachate was explored to determine the optimal process conditions, which were 500 min, 4 g/L and 8.88, respectively. The removal rates for COD and chroma under three optimal conditions were obtained by the single factor control method: 89% and 70%; 95.56% and 70%; and 85% and 87.5%, respectively. Under optimal process conditions, the overall average removal rates for ammonium nitrogen (NH4+–N) and COD in the leachate for the combination of TiO2 nanoparticles and an aged waste reactor were 98.8% and 32.5%, respectively, and the nitrate (NO3−–N) and nitrite nitrogen (NO2–N) concentrations were maintained at 7–9 and 0.01–0.017 mg/L, respectively. TiO2 nanoparticles before and after the photocatalytic reaction were characterized by emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Fourier transform infrared spectrometry. In addition, TiO2 nanoparticles have excellent recyclability, showing the potential of the photocatalytic/biological combined treatment of landfill leachate. This simulation of photocatalysis-landfilling could be a baseline study for the implementation of technology at the pilot scale.

Innovative Materials and Processes for Removal of Biopersistent Pollutants

“…As evidence of the high interest in the topics covered, to date, all the papers have been cited in other works, reaching 18 citations [5], 6 citations [6,7], 5 citations [3,10], 4 citations [4], 2 citations [1,8,9], and 1 citation [2].…”

“…A range of different but complementary topics were addressed, from environmental regulation [1] to the development of applications that can be useful in supporting decisions [2][3][4]. Furthermore, many studies analyzed how the modification of some materials can be effective for the reduction in pollutant dispersions [5][6][7][8][9] and the application of an innovative plant configuration [10].…”

A Recent Progress in the Leachate Pretreatment Methods Coupled with Anaerobic Digestion for Enhanced Biogas Production: Feasibility, Trends, and Techno-Economic Evaluation

“…Cai et al [107] used cetyltrimethylammonium bromide bentonite-titanium dioxide photocatalytic system to pretreat the leachate, which improved the degradation of NH 3 -N and COD and achieved the removal of up to 37% and 82% in one hour, respectively [108]. To degrade contaminants from leachate, Yasmin et al [109] used a photocatalytic technique with a TiO 2 /Ag composite and a biological treatment with a Candida tropicalis strain under visible light irradiation.…”

Photocatalysis for Heavy Metal Treatment: A Review

“…When the semiconductor material is irradiated by light, electrons (e − ) located in the valence band may jump to CB and may leave a positively charged hole (h + ) on the VB if the energy of a photon in the incident light is greater than or equal to the bandgap energy between the semiconductor valence band (VB) and the conduction band (CB). This pair of h + and e − can, respectively migrate to the surface of the semiconductor to undergo a series of oxidation and reduction reactions, which are embodied in the conversion of different valence states in the treatment of heavy metals [8][9][10]. In the photocatalysis process, the most essential limiting factors are the high energy requirements of the incident light caused by the wide bandgap and the easy recombination of photogenerated carriers (e − and h + ).…”