Laboratory Study on Efficiency of Bioadsorbents for the Removal of Nitrate from Aqueous Solutions
Subject Areas : environmental management
Karamat Akhavan Giglou
1
(Ph.D Student., Department of Water Engineering, Sari Agricultural Sciences and Natural Resources University * (Corresponding Author))
Ali Shahnazari
2
(Associate Prof., Department of Water Engineering, Sari Agricultural Sciences and Natural Resources University)
Bahman Yargholi
3
(Assistant Prof., Agricultural Engineering Research Institute, Agricultural Research Education and Extension Organization (AREEO), Karaj, Iran)
Keywords: Nitrate, Adsorbent, Aqueous solution, Bioadsorbent,
Abstract :
Background and Objective: Today, development of irrigated lands is faced with limited resources. With the increased water scarcity, the importance of using municipal, industrial and agricultural wastewater is increasing. This study was conducted on laboratory scale to investigate the efficiency of some bioadsorbents (rice husks, wheat straw, woodchips and cotton stalks) in removing nitrate from aqueous solutions and their application as bio filters in agricultural wastewater treatment. Method: First, absorbents were well-washed with distilled water, dried and crushed by the mill, and percolated through a standard sieve mesh 30 to obtain uniform powder from the absorbent samples. In order to prepare the required concentrations, nitrate solution was added to the distilled water with certain amount of potassium nitrate. For each bioadsorber, a spectrophotometer was used to measure the extent of nitrate removal at contact periods in order to determine the periods required to reach equilibrium, the optimum pH values of adsorbents, and the suitable concentrations of adsorbents. Findings: Results indicated the significant differences at the confidence level of 99% among the adsorbents in removing nitrate and these adsobents significantly reduced the nitrate in aquous soloutions. In the four adsorbents, the nitrate removal rates at the studied contact periods (5, 10, 20, 30, 60 and 90 minute) were statistically significant at the confidence level of 99%. Results from determining the suitable concentrations of the four studied adsorbents to reach the maximum efficiency showed that 1 g in 40 ml solution was the most suitable concentration. Moreover, reduction in the adsorbents amounts reduced their efficiencies. Study of isotherm models indicated that for all the studied adsorbents correlation coefficients in Langmuir’s isotherm model were higher compared to Friedrich isotherm model. Therefore, Langmuir isotherm model was more suitable for predicting nitrate removal from aqueous solutions by bioadsorbents. Discussion and Conclusion: Plant absorbers significantly reduce the amount of nitrate in aqueous solution. In this study, Langmuir model can be used as an adsorption isotherm.for adsorption of the bioadsorbents.
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- Jennings, G. D., Sneed, R. E. 1996. Nitrate in drinking water. North Carolina Cooperative Extension Service.
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- جبلی، سید جلال، «راهکارهای کاهش اثرات سوی پسابهای کشاورزی»، مجموعه مقالات همایش اثرات زیستمحیطی پسابهای کشاورزی بر آبهای سطحی و زیرزمینی، کمیته ملی آبیاری و زهکشی، 1380، ص: 12-24.
- Kapoor, A., Viraraghavan, T. 1997. Nitrate removal from drinking water review. Journal of environmental engineering, 123(4), 371-380.
- Liu, A., Ming, J., Ankumah, R. O. 2005. Nitrate contamination in private wells in rural Alabama, United States. Science of the total environment, 346(1), 112-120.
- Jennings, G. D., Sneed, R. E. 1996. Nitrate in drinking water. North Carolina Cooperative Extension Service.
- کرد، ایرج، «بررسی میزان نیترات و نیتریت در منابع آبهای زیرزمینی شهرستان نهاوند»، کتاب مقالات هشتمین همایش ملی بهداشت محیط، آبان 1384، 20ص.
- محسنی، انوشیروان، «مشکلات بهداشتی نیترات در آبهای آشامیدنی (خطرات بهداشتی وجود نیترات در آبهای آشامیدنی)»، مجله علمی پژوهشی دانشگاه علوم پزشکی مازندران شماره 15، تابستان 1376، ص 45-51.