Effect of biosolids application on soil chemical properties and uptake of some heavy metals by Cercis siliquastrum

The objective of this study is to investigate the effect of three kinds of biosolids usage on soil chemical properties and uptake of heavy metals by Cercis siliquastrum leaves. The experiment was carried out in a completely randomized block design with seven treatments including: no fertilizer as a control (C), sewage sludge (SW), cow manure (CM), municipal solid waste compost (MC), mixture of sewage sludge and cow manure (50% SW + 50% CM), mixture of sewage sludge and municipal solid waste compost (50% SW + 50% MC) and mixture of cow manure and municipal solid waste compost (50% CM + 50% MC) at three levels of 0, 2.5 and 5 kg/shrub and three replicates in calcareous sandy loam soil at the botanical garden of Mobarekeh steel company. After 180 days, soil samples were collected from 30 cm depth and leaves assemblage. Results showed that the treatments had significant effect (P < 0.05) on organic matter content, pH, electrical conductivity and cation exchange capacity of the soil. Total diethylen-triamine pent acetic acid (DTPA) extractable concentrations of Zn, Fe and Pb increased significantly (P < 0.05) in biosolid treatments. Between unwashed and washed metals concentrations of leaves, significant differences were shown, so it appeared that the source of metals on leaves was mainly airborn.Key words: Biosolids, soil chemical properties, heavy metals, Cercis siliquastrum

Toluene degradation by free staphylococcus gallinarum and immobilized on multi-walled carbon nanotubes

Hydrocarbons pollution is a most important environmental and healthanxiety . Using free and immobilized bacteria could be a suitable attitude to find a proper bioaugmentation agent. A toluene degrading bacterium was isolated from oil-contaminated environs (located in Bandar-Anzali, Guilan, Iran). The strain was molecularly identified as Staphylococcus gallinarum ATHH41 (Accession number: KX344723) by partial sequencing of 16SrDNA gene. The response surface methodology (RSM) was expended for biodegradation of the toluene by ATHH41. The central composite design (CCD) was utilized to optimize pH, temperature, and toluene concentration by ATHH41. In accordance with the optimization purpose of the Design-Expert software, the optimum circumstances of toluene degradation were obtained when pH, temperature and toluene concentration were adjusted to 7.68, 31.73°C and 630.04 mg.l-1, respectively. Multi-walled carbon nanotubes (MWCNTs) were used to immobilize the strain. Infrared spectroscopy and scanning electron microscopy showed that the cells adhered to the MWCNT surface and developed a biofilm. Results reveal that free cells were able to degrade 68.01% of the toluene as the sole carbon and energy source within 24 h under optimized conditions. The immobilized cells reached 95.68%

Effect of Grit Chamber Configuration on Particle Removal: Using Response Surface Method

In recent years ever-increasing industrial growth has resulted in a significant increase in the production of wastewater, this wastewater sometimes contains high levels of suspended solids. Therefore, the need to formulate an appropriate course of action for managing this wastewater has reached a critical level. In this study, the removal of suspended particles in wastewater that were a byproduct of an idustrial cut stone production process were investigated. For these purposes, a laboratory grit chamber was employed, and response surface methodology (RSM) was used to simulate the contributing parameters in the settling process. In order to study the performance of the grit chamber, factors such as flow rate, inlet location and mesh size, parameters of pH, COD, BOD, TSS and turbidity in influent and effluent were monitored. Results indicated that values of pH, COD and BOD in raw wastewater were within the standard range of discharging wastewater. The results indicated that the model with a high correlation of 0.95 was able to simulate the process. In addition, turbidity removal was found to be affected by three parameters among which mesh size and its interaction with the flow rate were the most influential ones

The role of exopolysaccharides from a chromate reducing Pseudomonas aeruginosa in resistance to hexavalent chromium and antibiotics

زمینه و هدف: کروم شش ظرفیتی (VI) یکی از اکسید کننده های بسیار قوی و جز عناصر سرطان زای گروه A است که در پساب صنایع مختلف وجود دارد. اگزو پلی ساکاریدهای (EPS) ترشح شده توسط باکتری های موجود در این پساب ها می تواند نقش موثری در افزایش مقاومت باکتری ها به این عامل نامساعد ایفا نماید. این تحقیق با هدف بررسی نقش EPS باکتری های مقاوم به کرومات در احیای کروم VI و مقاومت آنتی بیوتیکی آن ها صورت گرفته است. روش بررسی: این مطالعه مقطعی- آزمایشگاهی بر روی باکتری های مقاوم به کرومات موجود در انواع مختلف پساب صورت گرفت. حداکثر غلظت قابل تحمل کرومات (MTC)، مقدار ترشح EPS، احیای کرومات توسط EPS و مقاومت آنتی بیوتیکی جدایه انتخابی به روش کیربی- بائر تعیین گردید. یافته ها: جدایه موثر که واجد بالاترین MTC ( mM128) و حداکثر توان ترشح EPS ( mg.ml-1117/0) بود، بر اساس نتایج تست های بیوشیمیایی گونه ای از سودوموناس آئروژینوزا تشخیص داده شد. مقایسه راندمان 61 درصدی احیای کرومات توسط EPS با راندمان 78 درصدی احیای سلولی کرومات حاکی از نقش قابل توجه EPS در احیای کرومات بود. این باکتری به طیف وسیعی از آنتی بیوتیک ها نیز مقاومت نشان داد. نتیجه گیری: افزایش کروم VI در محیط منجر به افزایش مقاومت باکتری ها با به کارگیری انواع مکانیسم های سازشی چون افزایش ترشح EPS می گردد و به موازات آن مقاومت آنتی بیوتیکی نیز افزایش می یابد. این مقاومت توام از لحاظ پزشکی بسیار مهم بوده و می تواند اطلاعات ارزشمندی در ارتباط با مکانیسم مقاومت آنتی بیوتیکی، ژنتیک پلاسمید و اکولوژی جدایه مورد نظر در اختیار ما قرار دهد

Biodegradation of Phenol by Indigenous Bacterium Isolated from Contaminated Soil of Esfahan Steel Company Zone

Industrial processes produce high volumes of wastewater containing organic pollutants such as phenol and its derivatives. These contaminants include materials that are serious threats for environmental, human and soils characteristics . There are lots of methods for phenol removing from contaminated soils that one of them is biodegradation. In this study with the aim of phenol biodegradation, take action to isolation of bacteria from contaminated soil of Esfahan steel factory. Some properties of soil such as pH, organic matters, electrical conductivity and phenol concentration were determined. Enrichment of isolated bacteria was done. The best indigenous bacterium was selected according to its growth in presence of 400 mg.L-1 of phenol during 24h for further biodegradation studies and molecular identification. Results showed that according to phylogenetic analysis, the best isolated bacterium was the strain of Enterobactersp. that could remove 400 mg.L-1phenol during 72 hours. The results of this study shown that indigenous bacterium can remove organic pollutant such as phenol from contaminated soil

Study of Growth Process and Phenol Biodegradation by a Bacterium Isolated from Wastewater (in vitro)

Phenol is a carbonic compound that is dangerous for humans at a concentration of 0.5 ppm in the environment. The best phenol removal from coal tar wastewaters is achieved by bioremediation. In this study, we isolated indigenous bacteria from phenolic wastewater and adapted it to a high concentration of phenol for its removal from wastewater. We also investigated the growth and removal curves of the bacteria in media with 2000 and 4000 ppm of phenol. It was observed that after lag phases of 24 and 48 hours, they grew and removed all of the phenol concentration over 264 and 312 hours. It was also found that this isolate was able to remove 2233 ppm of phenol in natural wastewater over a period of 120 hours. Identification tests showed that it is a gram-negative bactetium possibly belonging to the pseudomonas species. Phenol concentrations in wastewater can be reduced over a shorter period of time by using either this isolate alone or a group of them

Reclamation of Phenol Contaminated Wastewater by Paenibacillus sp.

Phenol and its compounds are toxic and hazardous material for environment even in low concentrations. So removal of these compounds from wastewaters is very important. There are many methods for removal of phenol from contaminated wastewaters among which biodegradation is more attractive. In this study presuming the availabity of phenol degrading-bacterium in phenolic wastewater, indigenous bacterium were isolated and identified by PCR. The growth curve and phenol removal of this bacterium were prepared. Results showed that the best isolated was the stain of Paenibacillus that can remove 1000 mg.l-1 phenol during 96 hours. The results showed that indigenous bacterium can remove high concentration of phenol from contaminated wastewater

Isolation, Purification and Identification of Indigenous Bacteria from PAHs Polluted Soil

PAHs are toxic compounds with carcinogenic effects on humans that are released into the environment by incomplete combustion of fossil fuels. Three methods are commonly employed for PAHs pollutant removal: physical, chemical, and biological. From among these, the biological method which typically contains microbial processes and transforms pollutants to nontoxic or less toxic substances is the most innocuous and effective solution. In this study, attempts were initially made to enrich, isolate, and purify indigenous bacteria from PAHs polluted soil. In the second stage, the PCR method was exploited to identify the bacteria that had the capability of growth and reproduction in polluted conditions. It was found that the degrading bacteria are component species of gram negative bacilli determined as Shewanella, Pseudomonas, and Achromobacter. The results of the present study indicate that the bacteria have the best performance in PAHs removal from polluted environments

Effect of Grit Chamber Configuration on Particle Removal: Using Response Surface Method

In recent years ever-increasing industrial growth has resulted in a significant increase in the production of wastewater, this wastewater sometimes contains high levels of suspended solids. Therefore, the need to formulate an appropriate course of action for managing this wastewater has reached a critical level. In this study, the removal of suspended particles in wastewater that were a byproduct of an idustrial cut stone production process were investigated. For these purposes, a laboratory grit chamber was employed, and response surface methodology (RSM) was used to simulate the contributing parameters in the settling process. In order to study the performance of the grit chamber, factors such as flow rate, inlet location and mesh size, parameters of pH, COD, BOD, TSS and turbidity in influent and effluent were monitored. Results indicated that values of pH, COD and BOD in raw wastewater were within the standard range of discharging wastewater. The results indicated that the model with a high correlation of 0.95 was able to simulate the process. In addition, turbidity removal was found to be affected by three parameters among which mesh size and its interaction with the flow rate were the most influential ones