This study examines the potential of converting organic waste into valuable biofuels, including biohydrogen, biomethane, and biopropane, through microbial fermentation and anaerobic digestion. Organic residues such as food waste, agricultural byproducts, and sewage sludge serve as renewable feedstocks for these bioprocesses, enabling the transformation of otherwise discarded materials into energy-rich compounds. By harnessing the metabolic capabilities of microorganisms, these processes offer a sustainable approach to waste management while simultaneously generating renewable energy, contributing to both environmental and economic benefits.Biohydrogen, produced through dark or photo-fermentation, represents a clean and high-energy fuel with minimal greenhouse gas emissions. Similarly, biomethane generated via anaerobic digestion can be used as a direct substitute for natural gas, while biopropane offers potential as a renewable alternative for industrial and domestic energy applications. These biofuels not only reduce dependence on fossil fuels but also play a critical role in mitigating climate change by capturing carbon present in organic waste streams and preventing methane release from uncontrolled decomposition. Recent research has focused on optimizing microbial consortia, refining reactor designs, and improving process parameters such as temperature, pH, and nutrient availability to enhance biofuel yield and process efficiency. Advances in scaling up these technologies have demonstrated their feasibility for industrial applications, supporting the development of integrated biorefineries that convert waste into multiple valuable products.Overall, the microbial conversion of organic waste into biofuels exemplifies a circular economy approach, where waste materials are transformed into sustainable energy resources. By promoting renewable energy generation, reducing greenhouse gas emissions, and improving waste management, these bioprocesses highlight the potential of biotechnology to address pressing environmental challenges while fostering sustainable industrial practices.

Sawdust is an organic solid waste material of high adsorbing potential in removal of heavy metal ions from wastewater, so it can be used in treating industrial waste.In this study, the removal of copper, chromium, and nickel from laboratory prepared wastewater, through sawdust, was investigated. Waste water containing heavy metals was added was to sawdust to evaluate the rate of metal ion adsorption in different conditions of acidity, contact times and concentrations.The results indicated that the adsorption of these heavy metal ions increased with an increase in pH and reached a maximum at pH=5. In addition, percent adsorption depended on kind of ion, so that at pH=5 the percent adsorptions for Cu (II), Ni (II) and Cr (III) were 65%, 56% and 50% respectively. Adsorption increased with the initial concentration of metal ions and then decreased, because of sawdust saturation. Saturation capacity per gram of sawdust for copper, nickel and chrome ions was 28.2, 11.8 and 23.2 ppm respectively. Also adsorption increased with contact time. However, this process was rapid, and in the initial 10 minutes, percent adsorption got to between 45% and 65%. And finally the favorable needed time was determined to be 60 minutes.

Background: Agricultural waste has been proposed as an alternative energy resource to meet fossil fuel crisis, green house emission, and other environmental impacts worldwide. In Iran, rice husk and bagasse are main resources of biomass which can be used to produce syngas. This paper deals with a simplified model of combined gasification of coal and biomass processes considering chemical equilibrium.Results: It should be noticed that the CO2 which is produced from agricultural waste gasification is natural because the biomass absorbs CO2 from nature and gives it back after gasifying; however, mixing agricultural waste with coal leads to enrich syngas quality and gasifier efficiency.Conclusions: In this regard, an advanced coding was developed to simulate the thermodynamics of the co-gasifier and to find the produced syngas composition. The effects of moisture content, steam-to-biomass ratio, and gasifier temperature are then discussed on the system performance. Additionally, co-gasification of rice husk/coal was compared with co-gasification of bagasse/coal. The results indicated that adding coal to biomass increases lower heating value of syngas from 4, 694 kJ/Nm3 to 5, 321 kJ/Nm3 and gasifier efficiency from 71.29% to 77.85%.

In this research, a high porous silicate mining waste that was prepared from Syah Kamar Polymetal Porphyry mine in order to malachite green dye (MG) removal has been applied. The characterization of this natural mineral was determined using the XRD, XRF, SEM and FT-IR analysis. The MG adsorption onto high porous activated waste was studied based on the parameters of pH, temperature, adsorbent dosage, initial dye concentration and contact time. The equilibrium and kinetic adsorption models were experimentally investigated. The obtained data have suggested that the process of MG removal followed up the Sips isotherm and pseudo-second order kinetic. The thermodynamic parameters values consist of Δ G˚ , Δ H˚ and Δ S˚ confirms that the adsorption of MG is spontaneous and exothermic reaction. In the optimal condition the removal of MG was more than 93%. This method has a number of advantages, including being low-cost and non-toxic and the availability of natural adsorbent.

urpose: Chemical decomposition was studied as a potential method for the rapid conversion of waste to organic fertilizer.Methods: Chemicals were screened, and process parameters were optimized. The physicochemical properties, phytotoxicity, and manurial efficiency of the product were assessed. A prototype machine was fabricated for the operation.Results: Chemical treatment of ground fresh waste with HCl (0.25 N, 50 ml kg-1) for 30 min followed by KOH (0.5 N, 100 ml kg-1) for 30 min at 100 oC, and ambient pressure yielded a product that could be used in place of conventional organic manure. Only 8–14 h were required to complete the entire process. No by-product or leachate was produced. The quality of the product was comparable to that of conventional composts, except for the absence of microorganisms. The fortified organic fertilizer enhanced the yield of vegetables in pot trials. The process and the prototype machine were found beneficial by a public evaluation.Conclusions: The new thermochemical waste processing method provides a quick and sustainable solution for hygienic waste disposal and the production of organic fertilizer.

Pistachios are one of the most important agricultural products in Iran and play an important role in the country's exports. Agricultural by-products are destroyed in different stages without being processed, and transformation industries in Iran do not take full advantage of all the components of an agricultural product. Chemical and mineral compounds are compounds that are either produced in the organs of different plants or absorbed by the plant from the environment. Pistachio shell is the main part of pistachio by-products. The presence of these compounds in pistachio leaves and skins can be used as a source for human use in industry and agriculture. In this research, the detection and measurement of organic and mineral substances in pistachio soft skins, which are produced in pistachio collection centers along with pistachio processing, and it was concluded that these substances are mostly considered as waste and waste, they can be used The identification of these substances was done with the help of usual laboratory methods and also with GC-MS method. The primary organic materials in pistachio skin include various types, about fifty percent of these materials are structural organic materials such as cellulose and pectin. Types of proteins and amino acids that are nitrogen-containing molecules. They make up about 11-15% of the volume of available materials. The share of fats is between 5 and 7 percent, and raw ash, which contains various elements, constitutes 10 percent.

Purpose: Traditional organic formulations are widely used as a plant growth promoters; however, the knowledge on the microbial aspect of traditional organic formulations is still limited. The aim of this study was to illustrate the cultivable bacterial diversity of various traditional organic formulations and their potential for early plant growth promotion.Methods: Five different traditional organic formulations such as 100 %panchagavya, 33% panchagavya, plant extract with native microorganisms, commercial organic fertilizer extract with two percent leaf soil extract and commercial organic fertilizer extract with 2 % yogurt were prepared and used in this study. The liquid fraction of these traditional organic formulations were used to analyze the beneficial effect on plant growth by seed treatment and foliar applications.Results: Bacterial 16SrDNA analysis revealed that the isolates fell into forty-three different genera, which can be grouped into seven different classes, such as Alphaproteobacteria, Actinobacteria, Bacilli (or Firmibacteria), Betaproteobacteria, Cytophagia, Flavobacteriia and Gammaproteobacteria. Higher bacterial diversity was observed in cow dung followed by 33 and 100 %panchagavya.Radish and Chinese cabbage seed germination and growth were significantly improved by traditional organic formulations compared to control.Conclusion: The results of this study showed that the bacterial diversity changes depend on the type and concentration of ingredients used in traditional organic formulations.Substantial increase in plant growth by the traditional organic formulations indicates the suitability of using these organic preparations in eco-friendly agriculture.