• Journal of the Korea Organic Resources Recycling Association
• /
• v.29 no.3
• /
• pp.35-40
• /
• 2021

In order to investigate the degree of solubilization of sewage sludge using sono-activated persulfate(UV/PP), VSS reduction rate, solubilization rate and extracellular polymeric substances were measured. Ultrasonic(US) and alkali·ultrasonic method using sodium hydroxide(US/SH) were compared. Under the persulfate·ultrasonic conditions, the VSS reduction rate and the solubilization rate increased to 27.6% and 58.9%, respectively. TB-EPS as Carbohydrate and Protein were extracted by 770 mg/L and 2,162 mg/L. Compared to the other methods, US and US/SH, the VSS reduction rate and solubilization rate were higher. And also, according to the TB-EPS values, cell wall destruction was more efficient.

• Journal of Soil and Groundwater Environment
• /
• v.22 no.2
• /
• pp.17-25
• /
• 2017

The efficiency and mechanism of electrochemical phenol oxidation using persulfate (PS) and nanosized zero-valent iron (NZVI) were investigated. The pseudo-first-order rate constant for phenol removal by the electrochemical/PS/NZVI ($1mA^*cm^{-2}/12$ mM/6 mM) process was $0.81h^{-1}$, which was higher than those of the electrochemical/PS and PS/NZVI processes. The electrochemical/PS/NZVI system removed 1.5 mM phenol while consuming 6.6 mM PS, giving the highest stoichiometric efficiency (0.23) among the tested systems. The enhanced phenol removal rates and efficiencies observed for the electrochemical/PS/NZVI process were attributed to the interactions involving the three components, in which the electric current stimulated PS activation, NZVI depassivation, phenol oxidation, and PS regeneration by anodic or cathodic reactions. The electrochemical/PS/NZVI process effectively removed phenol oxidation products such as hydroquinone and 1,4-benzoquinone. Since the electric current enhances the reactivities of PS and NZVI, process performance can be optimized by effectively manipulating the current.

• Journal of Soil and Groundwater Environment
• /
• v.27 no.1
• /
• pp.31-38
• /
• 2022

The common algae and industrial waste, chlorella and red mud, were co-pyrolyzed in carbon dioxide condition to fabricate iron-biochar composite. In order to investigate the direct effect of chlorella and red mud in the syngas generation and the property of biochar, experiments were performed using mixture samples of chlorella and red mud. The evolution of flammable gasses (H₂, CH₄, CO) was monitored during pyrolysis. The produced biochar composite was employed as a catalyst for persulfate activation for methylene blue removal. BET analysis indicated that the iron-biochar composite mainly possessed meso- and macropores. The XRD analysis revealed that hematite (Fe₂O₃) contained in red mud was transformed to Fe₃O₄ during co-pyrolysis. The composite effectively activated persulfate and removed methylene blue. Among the composite samples, the composite fabricated from the mixture composed of 1:2 chlorella:red mud showed the best performance in syngas generation and methylene blue removal.

• Clean Technology
• /
• v.12 no.4
• /
• pp.244-249
• /
• 2006

The photocatalytic degradation of trichloroethlylene (TCE), has been investigated over $TiO_2$ photocatalysts irradiated with solar light. The effect of operational parameters, i.e., initial TCE concentration, $TiO_2$ concentration, pH and additives ($H_2O_2$, persulphate($S_2O{_8}^-$)) on the degradation rate of aqueous solution of TCE has been examined. The results presented in this work demonstrated that degradation of the TCE with $TiO_2/solar$ light was enhanced by augumentation in $TiO_2$ loading, pH, and adding additives but was inhibited by increase in initial TCE concentration. Also individual use of $H_2O_2$ was far more effective than using persulphate in TCE removal efficiency. Furthermore, the relative toxicity with a $solar/TiO_2/H_2O_2$ system was about 15% lower than with a $solar/TiO_2/persulphate$ system and about 35% lower than with a $solar/TiO_2$ system within a reaction time of 150 min, respectively.