Comparison of heavy metals contamination and ecological risk between soils enriched with compost and chemical fertilizers in the North of Iran and ecological risk assessment

Background: Due to the fact that in the process of car painting in the automotive industry, sludge containing dangerous compounds of benzene, toluene, ethylbenzene, xylene which cannot be released into the environment without purification, is inevitably produced, this study was conducted to investigate the feasibility of removing BTEX (benzene, toluene, ethylbenzene, and xylene) from the paint sludge of Saipa Automotive Company using Eisenia fetida worms. Methods: This is an experimental study. First, mixtures with different proportions of sludge were prepared and loaded in suitable boxes. After preparing the desired sludge, their quantitative and qualitative characteristics were determined in terms of type and amount of BTEX, volatile materials, moisture content, and C/N ratio. Then, to check the changes in BTEX, sampling was performed on different days during 90 days. BTEX measurements were performed using GC-MS method (NIOSH Method 1501). Results: The results showed that in the best mixing ratio of sludge, the amount of benzene decreased from 3 mg to less than 0.01 mg in 30 days, toluene decreased from 1.5 mg to zero over a 45-day period, ethyl benzene was reduced from 7 mg to zero mg over 70 days, and xylene decreased from 18 mg to 0.9 mg over 90 days. In addition, in the same optimal mixing ratio, the amount of volatile organic matter, pH, and C/N ratio also had a decreasing trend in the vermicomposting process. Conclusion: According to the results, E. fetida worms are able to work in mixed sludge and have the ability to break down BTEX.

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Investigating the reduction of BTEX in automotive paint sludge combined with biological sludge by vermicomposting process using Eisenia fetida

Avili

Takdastan

Atabi

et al. 2021

“…Cd is an environmental pollutant heavy metal that enter the environment by both natural and synthetic sources (16)(17)(18). The most important sources of artificial soil contamination include discharge of sludge and industrial wastewater, the use of fertilizers and superphosphate, buried non-ferrous scrap in the ground and agricultural lands around mines of Pb and zinc or refineries (18)(19)(20)(21).…”

Section: Introductionmentioning

confidence: 99%

Concentration of cadmium, arsenic, and lead in rice (Oryza sativa) and probabilistic health risk assessment: A case study in Hormozgan province, Iran

Rezaei

Alipour

Sharafi

et al. 2021

Background: The presence of toxic heavy metals in cereal grains like rice is one of the main human and environmental health concerns. Their importance is because of their non-biodegradability nature, high half-time, and bioaccumulation ability in the human body. Among heavy metals, cadmium (Cd), lead (Pb), and arsenic (As) are most critical, so their concentrations in rice were evaluated in this study. Methods: In this study, the concentration of Cd and Pb was determined by graphite-furnace atomic absorption spectrometer (GF-AAS), while the concentration of As was measured by atomic spectrum poll after acid digestion of the milled rice samples. The probabilistic health risk assessment of Cd, As, and Pb through consumption of different types of rice including local rice and two types imported from India (IND) and Pakistan (PAK), was estimated for the adults in Hormozgan province using Monte Carlo simulation (MCS) technique. Results: It was revealed that the concentrations of all Cd, As, and Pb in the local rice samples were lower than those in the PAK and IND samples. The average concentration of As, Pb, and Cd in the rice samples were 0.045, 0.057, and 0.022 mg/kg, respectively. The estimated total target hazard quotient (TTHQ) for this population was lower than 1, representing negligible non-carcinogenic risk through rice consumption. However, total carcinogenic risk (TCR) via As intake showed a considerable carcinogenic risk (TCR > 1E-4) for this population. Conclusion: According to the results, it is necessary to perform continuous monitoring for concentration of Cd, As, and Pb especially in the imported rice samples.

“…On the other hand, phosphate compounds in the contaminated soils such as Pb pollution are known as a suitable method for stabilization of heavy metals (16)(17)(18). However, the efficiency of such compounds in soils with physical and chemical properties is not similar (19), which needs to be studied separately in different studies.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Pb by organic and inorganic phosphate and calcium sources in an acidic Pb-polluted soil amended with cow manure

Baghaie

Keshavarzi

2021

Background: Chemical stabilization of heavy metals in acidic soil is one of the important points in environmental pollution. Thus, this research was conducted to investigate the effect of organic and inorganic amendments on lead (Pb) immobilization in the Pb-polluted soil. Methods: Treatments were consisted of applying cow manure (0, 15, and 30 t/ha), and applying cow bone and phosphate rock (5% (W/W)) in the Pb (0, 800, and 1600 mg Pb/kg soil)-polluted soil. The plant used in this experiment was canola. After 70 days, the plants were harvested and soil and plant Pb concentration was measured using atomic absorption spectroscopy (AAS). Results: Applying 15 and 30 t/ha of cow manure in the Pb (1600 mg Pb/kg soil)-polluted soil significantly decreased the soil Pb concentration by 14.3 and 17.2%, respectively. For plant Pb concentration, it was increased by 11.8 and 15.1%, respectively. A significant decrease in plant Pb concentration was measured, when the soil under cultivation of the plant was amended with 5% (W/W) phosphate rock powder. For the plants grown on the soil, which was amended with 5% (W/W), the plant Pb concentration decreased by 17.6%. In addition, applying organic and inorganic amendment significantly decreased the bio-concentration factor (BCF), while the soil microbial respiration increased. Conclusion: The results of this study showed that applying 15 and 30 t/ha cow manure or calcium and phosphorus sources such as cow bone and phosphate rock powder (5% (W/W) can decrease the soil Pb availability and prevent the Pb translocation from soil to plants.