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The effect of municipal solid waste compost on the reduction of lead and zinc toxicity and uptake of nutrients by two medicinal species Marrubium cuneatum and Verbascum speciosum in a soil contaminated with heavy metals
Sadegh Hosseinniaee, Mohammad Jafary, Ali Tavili, Salman Zare,
Volume 16, Issue 4 (3-2024)
Abstract
Background and Objective: The toxicity of heavy metals is one of the most important environmental issues in the current century. This research aimed to investigate the effect of municipal solid waste compost on the absorption of nutrients and lead and zinc metals in M. cuneatum and V. speciosum plants.
Materials and Methods: In a greenhouse experiment, compost at four levels (0, 1, 3 and 5% w/w) was completely mixed with natural soil contaminated with heavy metals (Pb and Zn). After six months of harvesting the plants, the shoot and root biomass was determined. Also, the concentration of macronutrients and micronutrients, Pb and Zn in the roots and aerial parts of plants and available Pb and Zn in the soil were measured using the ICP-OES. In order to investigate the correlation between the measured plant and soil parameters, principal component analysis (PCA) was performed
Results: Compost significantly improved the shoot dry weight of M. cuneatum and V. speciosum by 13 and 19%, respectively. 5% compost significantly reduced shoot lead by 64 and 34.4% in M. cuneatum and V. speciosum, respectively, compared to the control. Compost was more effective in increasing potassium, phosphorus, copper, and nickel than magnesium, manganese, and calcium, and increased shoot potassium by 22 and 32%, respectively, in M. cuneatum and V. speciosum compared to the control; this increase was 30 and 14% for copper and 19 and 21% for phosphorus, respectively. PCA analysis showed that, among the investigated elements, potassium, phosphorus and copper were most affected by composting and had the maximum role in improving plant growth and reducing lead toxicity.
Conclusion: Municipal solid waste compost improved the growth of M. cuneatum and V. speciosum and reduced phytotoxicity by immobilizing lead in the soil.
 

Investigating earthworm survival in diesel-contaminated soil remediation reactors
Behnaz Abdollahinejad, Mahdi Farzadkia,
Volume 17, Issue 2 (9-2024)
Abstract
Background and Objective: Earthworms are important in soil formation. They maintain soil structure and fertility and can be used as indicators to evaluate various changes and impacts. Therefore, the present study was developed to investigate the effects of diesel pollutant on the population and survival of the earthworm species E.fetida in the co-vermicomposting process.
Materials and Methods: This experimental study was conducted over 90 days to investigate the effects of diesel concentration on the survival of E.fetida in the co-vermicomposting process. One kilogram of soil contaminated with diesel, vermicompost, and raw activated sludge was added to each reactor in a ratio of 0.25:0.35:1. 10. Additionally, 20 adult E. fetida were added to the reactors with diesel concentrations of 10 and 30 g/L after the adaptation process.
Results: The survival of earthworms and the formation of cocoons in reactor number 3 were higher than in other reactors. Additionally, the amount of diesel removal in reactor number 3 (diesel concentration: 10 g/kg dried soil +20 E.fetida) was higher (70.5%) compared to the other reactors.
Conclusion: The results of the study showed that earthworm reproduction is more sensitive than survival or weight change to higher concentrations of diesel-contaminated soil. The presence of petroleum compounds in the soil is harmful for the growth of E.fetida, and its acute effects on the production of earthworm cocoons were observed.
 

Modification of anaerobic composting process using natural clinoptilolite zeolite on the quality of physical and chemical properties
Fariba Asghari, Ayoob Rastegar, Mohammad Hossien Saghi,
Volume 17, Issue 4 (3-2025)
Abstract
Background and Objective: Composting is a sustainable solution for recycling organic solid waste (OSW). Various compounds can be used to enhance the quality of compost. This study aimed to investigate the effects of zeolite on the physical and chemical characteristics of compost produced through the anaerobic process.
Materials and Methods: This analytical study was conducted in 1402 at Kimia Sabzevar Company, located 5 km from Rudab Road. Cow manure and natural clinoptilolite zeolite were used in varying proportions (0%, 5%, 10%, 15%, and 20% of the total reactor volume) to prepare fertilizer via the anaerobic method. After 30, 45, and 60 days, a total of 90 samples were collected and sent to the laboratory for analysis. Parameters such as pH, electrical conductivity, temperature, carbon-to-nitrogen ratio, and nitrate content were measured to evaluate the quality of the fertilizer product.
Results: The results showed that in the early stages, pH changes were less pronounced in treatments with varying zeolite percentages, ranging from 7.9 to 8.57. The addition of zeolite in the composting process influenced temperature dynamics, with higher zeolite percentages maintaining elevated temperatures. Moreover, the nitrate content increased by 15% during the process.
Conclusion: The findings indicate that adding zeolite to fertilizer enhances temperature stability, accelerates the composting process, and reduces the time required for fertilization. Additionally, zeolite improved the physicochemical properties of the fertilizer produced through the anaerobic process.
 

Technical, environmental and economic assessment of composting technology in municipal solid waste management: a case study of Tehran, 2023
Sara Ghobadi, Farhad Khosravani, Zohreh Bahmani,
Volume 18, Issue 3 (12-2025)
Abstract
Background and Objective: Managing municipal solid waste in megacities like Tehran, which generates approximately 8,500 tons of waste daily, presents significant environmental and economic challenges. Notably, biodegradable organic materials constitute an estimated 60–70% of this waste, necessitating effective management strategies to mitigate environmental impacts. This study aims to evaluate the technical feasibility, environmental benefits, and economic viability of implementing rapid composting technology as an innovative approach to managing Tehran's organic waste.​
Materials and Methods: A composting system with a daily processing capacity of 1,000 kilograms of organic waste was analyzed. Economic evaluation employed cost-benefit analysis, calculating financial indicators such as Net Present Value, Internal Rate of Return, Payback Period, and Profitability Index.
Results: The rapid composting technology demonstrated an NPV of 56.6 billion Iranian Rials, an IRR of 20.48%, and a PBP of 3 years and 5 months. The PI was calculated at 3.52, indicating strong economic attractiveness. Environmentally, this technology contributes to reducing landfill volume, lowering greenhouse gas emissions, producing high-quality compost, and decreasing reliance on chemical fertilizers.​
Conclusion: Implementing rapid composting technology for processing 1,000 kilograms of organic waste daily in a residential complex of 2,000 inhabitants in Tehran is both economically and environmentally justifiable. This approach offers a practical and sustainable solution for urban organic waste management.
 

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