ABSTRACT
A few elements of soil are radioactive. Soil can transfer radionuclide into plants feeding human. Sometimes their levels are as high as to be concern of human healthy. Rice has an important share for Iranian foods especially in north of Iran. Therefore we decided to obtain radionuclides concentration emitting g rays in Lahijan City [Northern Iran] rice fields using g spectroscopy. Twenty eight samples from rice field's soils and 12 samples from superficial soils were collected at a square of 10*10 m2 to get 2kg weight. To make dry samples were put into oven at 105oC for 24h. Then they were milled and 950 gr of each sample was transferred to Marinelli container with 1000cc volume, sealed and left for 40 days to get secular equilibrium. After measuring Ph, Electric conductivity and organic carbon, g spectroscopy was done to get sample gamma spectrum at 2000-6000 sec using HpGe detector. It was found 226Ra activity in rice fields of 29.273 +/- 0.72 Bqkg-1 and city soil of 31.02 +/- 1.1 Bqkg-1 and also 232Th activity of 37.47 +/- 1.12 Bqkg-1 for rice fields' soils and 40.47 +/- 1.68 Bqkg-1 for city soil were in standard mode. 40K activities mean value according to UNSCEAR; 2000 was found a little greater than standard. A little value of 137Cs was found in Lahijan rice fields and city soils that could be as a result of Chernobyl accident. In except of 137Cs, for three other under studied city soil elements, activities were greater than that of rice fields
ABSTRACT
In recent decade, phytoremediation technology is regarded very important because of its simplicity, inexpensiveness and use of natural resources and solar energy. In this study, we investigated the efficiency of remediation of contaminated soil with Lead and Cadmium by using native plants of Iran. We selected three native plants of Iran [Abutilon theophrasti, Amaranthus retoflexus and Zea maize] for this study. Extraction of soil and plant samples was performed by use of HNO3 ,HCl and HNO3, HClO4 and H2SO4 respectively. Concentrations of Lead and Cadmium in soil and plants were determined by Perkin-Elmer 603 atomic absorption spectrophotometer. Lead concentration in the roots of plants [Alkaline soil] was more than those in their shoots. In acidic soil [with exception of Zea maize], concentration of Lead in the shoots was more than its concentration in the roots of the plants. Concentrations of lead in the roots and shoots of Abutilon theophrasti, Amaranths and Zea maize in alkaline soil were [54.5 and 25.5 mg/kg], [69 and 37.6mg/kg] and [47 and 32mg/kg] respectively, and its respective concentrations in acidic soil were [71.4 and 92.5 mg/kg], [89 and 120.5mg/kg] and [85 and 66.7 mg/kg]. Cadmium concentrations in alkaline soil were [6.5 and 4mg/kg], [8 and 6.2 mg/kg] and [5.6 and 3.4 mg/kg] and in acidic soil were [5.8 and 4.5 mg/kg], [7.6 and 5.4mg/ kg] and [6 and 4.8 mg/kg] respectively. Plants in group 3 produced less biomass than those in control group, group 1 and group 2. Considering the increased rate of absorption of Lead and Cadmium and the amount of biomass produced by Zea maize and Amaranthus retoflexus in the acidic and alkaline soil, use of these native plants is recommended for refining the soil contaminated with heavy metals
ABSTRACT
Although silver can be used as an effective water disinfectant, it has some disadvantages such as its high costs and darkening of the skin and mucous membrane due to long-term exposure to high silver concentrations. Nanotechnology can solve such problems through reduction of silver content. The aim of this study was to evaluate the effect of nanosilver on removing the coliform bacteria from contaminated water. This bench-scale experimental study was carried out in a batch system on artificially contaminated water samples prepared by adding 5 ml effluent to 60 liters of tap water. In each run, the nanosilver suspension [30-180 microgL-1] was added to 6 containers [500 ml] of contaminated water and then a sample was taken every 20 minutes for a 100-minute period and tested for coliform according to the standard methods book. Results revealed that the coliform bacteria removal significantly increased with increasing the contact time of nonosilver [P=0.001], but there was no significant correlation between the nanosilver concentrations and coliform removal [P=0.6]. The maximum coliform removal [92.41%] was achieved within 100 minutes contact time for 60 microgL-1 of silver. Although nanosilver treatment is effective in removing coliform from contaminated water, further researches are required to study the efficacy of drinking water disinfection
ABSTRACT
Nowadays, most countries of the world have shortage of water due to many reasons such as population growth, rising of living standards, indiscriminate water use, and so on. Besides, in absence of adequate water resources, desalination of brackish and saline waters have been used to supply potable water. Freezing process is one of the methods which can be used to desalinate saline waters.The aim of this study was to survey freezing process to produce potable water from saline water of Persian Gulf shores. This study was conducted in lab-scale by using indirect contact freezing. Three samples of 50 liter were provided from Bushehr shores. The implemented process steps were freezing [crystallization], separation of crystals, surface washing, and thawing. Freezing of the samples [each in 0.5 liter containers] were performed by a refrigerator at -20°C and 0.1KW/h energy consumption. The removal efficiencies of TDS in the first, second, and third samples by first freezing process were 56, 56, and 51 percent, respectively. Moreover, the removal efficiencies by EC were 42, 44, and 40 percent, respectively. Meanwhile, the removal efficiencies of TDS in first, second, and third samples by second freezing process observed 69, 69, and 68 percent, respectively. Moreover, the removal efficiencies by EC were 61, 60. and 63 percent, respectively. Also, the removal efficiencies of TDS in first, second, and third samples by third freezing process were 72, 73, and 72 percent, respectively. Moreover, the removal efficiencies by EC were 77, 78, and 77 percent, respectively. The production of the potable water by this method was 15-20 percent of the entry water. According to the obtained results, potable water was obtained after third freezing of the saline water. Meanwhile, TDS of the produced water was less than maximum allowed concentration of Iranian standards
ABSTRACT
New studies indicate that nitrate concentration in groundwater is increasing in most cities. High concentrations of nitrate in water increase the potential health risk in the community and the environment. In infants, No[3-] is reduced to No[2-], which combines with hemoglobin in the blood to form met hemoglobin leading to blue-tinged blood for babies under six months old in particular, Namely, so-called [blue baby syndrome] and it also produce carcinogenic compounds. Therefore high nitrate concentration is important. The aim of the present study is removing nitrate from water using zero valent iron. Analyses were conducted on synthetic samples. These samples were analyzed considering reaction times, pH, initial nitrate and sulfate concentration. Results showed that at Nitrate with an initial concentration of 200mg L[1-] after 60 min of reaction at pH [s] 7, 6 and 5 about 67.8%, 72.5% and 88% was reduced, respectively in concentration of 100 and 300 mgL [pHN6] the removal efficiency is 60 and 83 percent, respectively. In sodium sulfate and nitrate with concentration of 300, the removal efficiency reached from 72 to 70 percent. Results show that the initial pH is important to achieve maximum efficiency of nitrate removal. So the lower pH levels increases removal efficiency of nitrate. All of the experiments indicated that removal is the highest in the first 5 min. Generally with an increasing initial nitrate concentration the removal efficiency of nitrate increases
ABSTRACT
In this study, the removal of As [V] from water resources by using aluminum-coated pumice as a new adsorbent was assessed. The features of the adsorbent coating layer were observed by X-ray diffraction [XRD] and Scanning Electron Microscopy [SEM]. The effects of various parameters such as adsorbent doses, pH, contact time, arsenate initial concentration and interfering ions in arsenic adsorption and achieving high removal efficiency were studied. The results showed that the adsorption of As [V] was extremely influenced by the phosphate interfering ions. It was also defined that more than 98% of As [V] was removed by 10 g/L of the adsorbent with initial As [V] concentration of 250 micro g/L at pH =7 and in 160 minutes. The adsorption equilibrium were analyzed by Langmuir and Freundlich isotherm models. Such equilibriums showed that the adsorption data was well fitted with Freundlich isotherm model [R[2] >0.99]. The data achieved from the kinetic studies were processed by kinetic models of pseudo-first-order. The results indicated that the pseudo-second-order model could describe the adsorption of As [V] by pumice coated with alum [R [2] >0.92]. According to achieved results, it was defined that aluminum-coated pumice not only was an inexpensive absorbent, but also a quite effective factor in removal of As [V] from water resources
ABSTRACT
A pilot anaerobic filter was used to remove COD from Babolsar fiberboard production wastewater. The anaerobic filter was packed with ceramic packings and operated at different organic loading rates of 2.4 and 8 kg COD/m3 /day, in 20, 10 and 5 days hydraulic retention time [HRTI], respectively. The reactor achieved COD removal of 80.3%, 81% and 79% for HRT 20, 10 and 5 days, respectively. In addition BOD and oil removal efficiencies were shown to be 80% and 60%, respectively. The results of this study suggest that using anaerobic filter is a reliable process for removal of COD from fiberboard manufacturing effluent