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Enhanced Removal of Phosphorus from Aqueous Solutions by Cation-Modified Hydrochar
(2023-10-01)
Wutthipattarathorn, Kamyaporn
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Thawornchaisit, Usarat
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Janyapoon, Suwannee
In this study, cassava stem-derived hydrochar was modified with sodium hydroxide (NaOH) treatment, followed by loading of minerals, was used to prepare cation-modified hydrochars with enhanced phosphate removal ability. Cassava stems were converted to hydrochar by hydrothermal carbonization at 240 °C for 60 min, then it was soaked in 2 M NaOH for 3 h. The NaOH-treated hydrochars were then loaded with iron (Fe), magnesium (Mg) and calcium (Ca). The cassava stems and the derived hydrochars were analyzed for carbon, hydrogen, nitrogen and oxygen content, surface morphology and elemental compositions. Methylene Blue Numbers (MBN) measured surface area and porosity, and pH at the point of zero charge (pHpzc) was determined. Modification with Fe, Mg and Ca improved phosphate removal efficiency of the resulting hydrochars. Treatment of synthetic wastewater containing 50 mg P/L at pH 7 with the dosage of 2 g/L of the cation-modified hydrochars for 360 min showed that phosphate removal efficiency of these modified hydrochars were-Fe-modified 81 %, Mg-modified 66 % and Ca-modified 56 %. When the adsorbent dosage increased to 20 g/L, more than 98 % of phosphate was removed by the hydrochars modified with Fe, Ca and Mg. In the same conditions, phosphate removal efficiency was for the NaOH-treated hydrochars-89 %, hydrochar derived from cassava steam-69 % and the starting material-59 %. The phosphate removal ability of these cation-modified hydrochars increased even when initial phosphorus concentration was increased to 100 mg P/L. This work demonstrated that an abundant agricultural residue, cassava stems, can be converted into effective phosphate adsorbents.
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Decolorization of Boron-Based Wood Preservatives by Ozonation for Recycling: Optimization of Process Parameters
(2022-12-15)
Yanchimpee, Pantakan
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Thawornchaisit, Usarat
Preservation of sawn timber from rubber trees with a water-soluble mixture of boric acid and borax generates a large quantity of colored wood preservative solutions and carries toxic metals, especially boron. To save costs, millers commonly reuse the colored mixtures in successive preservation cycles but regularly add boric acid and borax to maintain boron levels. However, this strategy affects both the color and the economic value of the treated wood. This paper presents a new strategy to treat the colored mixture of waterborne preservative solutions using ozonation for recycling purposes. At optimum conditions which are determined by response surface methodology, very high color removal (96-97 %) is achieved from ozone treatment of the wood preservatives with an initial COD concentration of 2,250 ± 40 mg/L and solution pH of 3.59 ± 0.02 for 65 min reaction time. The effluent can be reused in successive preservation cycles without degrading the wood quality in terms of the color of the processed timber and boron penetration in the end grain as well as the sides of the wood. Ozone treatment shows to be a promising color removal technology for sawn rubberwood industry, aimed at the reuse of waterborne preservatives, resulting in direct environmental and economic benefits.
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Sugarcane bagasse-derived hydrochar: Modification with cations to enhance phosphate removal
(2021-09-01)
Thawornchaisit, Usarat
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Onlamai, Tanrawee
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Phurkphong, Nontakorn
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Sukharom, Rawiwan
Cation modified hydrochars were synthesized by hydrothermal carbonization (HTC) of sugarcane bagasse, followed by impregnation of three different cations (Ca, Mg, and Fe) or co-precipitation of Fe3+ and Fe2+. HTC enhanced the hydrochar surface area and increased the enrichment of oxygen functional groups on the hydrochar surface confirmed by FTIR. The oxygen functional groups further improve the adsorption capacity for cations during hydrochar chemical modification. Physical appearance, FTIR and XRF confirmed that Ca2+, Mg2+ and Fe2+ or Fe3+ were well retained in the bagasse-derived hydrochar. The pH<inf>pzc</inf> values of all chemically modified hydrochars were greater than the unmodified hydrochar or bagasse alone. Modification with different cations improved phosphate uptake capacity. The Fe-modified hydrochar with about 45-50% Fe content showed greater phosphate removal efficiency than Ca-and Mg-modified hydrochars. In addition, hydrochars decorated by impregnation of Fe3+ demonstrated better phosphate removal than ones produced by co-precipitation of Fe3+ and Fe2+. Thus, chemically modified hydrochars could be used as an environmentally alternative adsorbent for phosphate removal from aqueous solutions.
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Optimizing acid leaching of copper from the wastewater treatment sludge of a printed circuit board industry using factorial experimental design
(2019-11-01)
Thawornchaisit, Usarat
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Juthaisong, Kamalasiri
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Parsongjeen, Kasama
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Phoengchan, Phonsiri
Heavy metal containing sludge from printed circuit board production (PCB) is not only classified as hazardous waste, but also as a potentially valuable raw material for copper recovery. Since sludge leaching is a significant first step in copper extraction yield via hydrometallurgy, we assessed the optimum copper acid-leaching conditions using a Design of Experiment (DOE) approach (33 full factorial design) and the multiple response method called the desirability (D) function. The effects of acid concentration, the ratio of acid volume to sludge quantity (“L/S ratio”), and leaching time on copper-leaching efficiency were evaluated. The model equation derived using Minitab 17.0 predicts that copper-leaching efficiency can reach 97.0% at optimal values of 0.84 M sulfuric acid, L/S ratio of 100:1, and a leaching time of 80 min. Experiments verified a 96.8% (σ= 0.4 %) copper-leaching efficiency. The small discrepancy between predicted and experimental data showed that the DOE approach was a suitable tool for predicting leaching efficiency from PCB sludge by sulfuric acid.
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Iron-modified biochar derived from rice straw for aqueous phosphate removal
(2019-01-01)
Thawornchaisit, Usarat
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Donnok, Korawan
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Samphoanoi, Natchaphat
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Pholsil, Pimwimon
Conversion of rice straw to biochar, followed by chemical modification of the biochar with iron salts under alkaline conditions can turn agricultural biomass waste into a useful adsorbent material for phosphorus removal. Study of the rice straw-to-biochar conversion process at various pyrolysis temperatures showed that biochar yield decreased with increased pyrolysis temperature: The yield of stable organic matter and specific surface area was found to be optimum at 400°C. An Fe coating process, through direct precipitation of FeCl<inf>3</inf>. 6H<inf>2</inf>O or co-precipitation of FeCl<inf>3</inf>. 6H<inf>2</inf>O and FeSO<inf>4</inf>. 7H<inf>2</inf>O on biochar, led to Fe-modified rice straw biochars. Based on physical appearance, SEM, FT-IR and XRF, we confirmed that Fe was well retained in the biochar. The pH<inf>pzc</inf> was approximately 7. 6 and 8. 0 for Fe(III) + Fe(II)-modified biochar and Fe(III) modified biochar. Therefore, the modified biochar could attract negatively charged phosphate species in a system, like natural water or domestic wastewater, where pH is normally less than their pH<inf>pzc</inf>. In laboratory batch adsorption tests, phosphate removal efficiency was enhanced, rising from about 35.4% in the unmodified biochar to 69.5% in Fe(III)+Fe(II)-modified biochar and 83.0% in Fe(III) modified biochar.
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Cellular lipid production of a heterotrophic bacterium isolated from poultry processing wastewater
(2014-01-01)
Ongmali, Rattiya
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Phunpruch, Saranya
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Thawornchaisit, Usarat
Cell growth and lipid production of a heterotrophic bacterium, R4.4 which accumulated the highest lipid content among 12 bacterial colonies being isolated from wastewater of a poultry processing plant in Thailand, were evaluated in this study. The culture was identified as Aeromonas sp. by 16S ribosomal DNA sequencing analysis.The highest lipid content was obtained when the cells were in the early stationary growth phase compared to the cells in the exponential and the late stationary phase. Over 50% of the fatty acid production by Aeromonas sp. KMITL-R4.4 were unsaturated fatty acids, including linoleic acid (C18:2, 43.2%), oleic acid (C18:1, 19.0%), and palmitoleic acid (C16:1, 8.2%). The culture had a preference for glucose and fructose as seen from the maximum biomass and lipid contents that were obtained. Among volatile fatty acid (VFA) species tested, acetic acid was the preferred substrate for lipid production but not favorable for cell growth. In addition, ammonium sulfate was found to be the best among nitrogen sources tested. The C/N ratio exerts significant impact on lipid production as seen from an increase of the lipid content from 10.8% to 18.2% by exposing the bacterial cells to a medium with lower nitrogen concentration (0.1g/l) and higher level of glucose (28 g/l).
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The potential of restaurant trap grease as biodiesel feedstock
(2011-01-01)
Hasuntree, Parichart
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Toomthong, Vichuta
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Yoschoch, Sukanda
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Thawornchaisit, Usarat
The possibility of using restaurant trap grease as feedstock in the production of biodiesel via acid catalyzed esterification is explored in this study. Sulfuric acid was used as a catalyst for the esterification reaction of free fatty acid (FFA) and methanol. The FFA levels of restaurant trap greases were reduced from 60.38±2.22 mg KOH/g to 11.60±1.60 mgKOH/g when conditions for biodiesel production are as follow: methanol-to-FFA ratio of 5:1, 5 wt.% H<inf>2</inf>SO<inf>4</inf>, and a reaction temperature at 60°C with a reaction time of 60 min. During the acid-catalyzed esterification, the percentage of methyl esters resulting from conversion of FFA in the obtained product was 83.59±1.51% based on the result of 1H NMR analysis. Data obtained from the 23 full factorial designs revealed that methanol-to-FFA ratio term had the most significant effect on the percentage of methyl esters, followed by the H<inf>2</inf>SO<inf>4</inf> concentration. Conversely, reaction time between 1 and 3 hours had no significant effect on the esterification of trap greases.
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Evaluation of phosphate fertilizers for the stabilization of cadmium in highly contaminated soils
(2009-06-15)
Thawornchaisit, Usarat
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Polprasert, Chongrak
The efficiency of three phosphate fertilizers including triple superphosphate (TSP), diammonium phosphate (DAP), and phosphate rock (PR) as stabilizing agents of cadmium-contaminated soils has been assessed in this study. Two types of assessment criteria, (a) the reduction of leachable cadmium concentration; and (b) the changes in Cd association with specific operational soil fraction based on the sequential extraction data, are used in the evaluation of stabilization performance of each fertilizer. Results of the study showed that after the 60-day stabilization, the leachable concentrations of Cd in PR-, DAP- and TSP- treated soils reduced from 306 mg/kg (the control) to 140, 34, and 12 mg/kg with the stabilization efficiency as TSP>DAP>PR. Results from the assessment of Cd speciation via sequential extraction procedure revealed that the soluble-exchangeable fraction and the surface adsorption fraction of Cd in the soils treated with PO<inf>4</inf> fertilizers, especially with TSP, have been reduced considerably. In addition, it is found that the reduction was correspondingly related with the increase of more stable forms of cadmium: the metal bound to manganese oxides and the metal bound to crystalline iron oxides. Treatment efficiency increased as the phosphate dose (based on the molar ratio of PO<inf>4</inf>/Cd) increased. In addition, it was observed that stabilization was most effective when using the molar ratio of PO<inf>4</inf>/Cd at 2:1 and at least 21-day and 28-day stabilization time for TSP and DAP, respectively. © 2008.
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Application of dried sewage sludge as phenol biosorbent
(2007-01-01)
Thawornchaisit, Usarat
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Pakulanon, Kesinee
The aim of this work was to determine the potential application of dried sewage sludge as a biosorbent for removing phenol from aqueous solution. Results showed that biosorption capacity was strongly influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH around 6-8. Biosorption capacity increased when initial phenol concentration was increased to 110 mg/L but beyond this concentration, biosorption capacity decreased suggesting an inhibitory effect of phenol on biomass activity. Biosorption capacity decreased from 94 to 5 mg/g when biosorbent concentration was increased from 0.5 to 10 g/L suggesting a possible competitive effect of leachable heavy metals from the sludge. The effect of Cu2+ on biosorption capacity was also observed and the results confirmed that the phenol biosorption capacity decreased when concentration of Cu2+ in the sorption medium was increased up to 15 mg/L. Desorption of phenol using distilled deionized water was less than 2% suggesting a strong biosorption by the biomass. © 2005 Elsevier Ltd. All rights reserved.

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