Research Background and Objectives

Huge production of different agricultural and municipal wastes is known as one of the most important problems in the modern agriculture and life style. Compost production from these available organic materials is a useful methodology to produce organic materials for use instead of chemical fertilizers. Usually, the composting process takes a long time because of poor microbial activity in the wastes, as result, the final product is not mature, and therefore the quality is low. Recently, different biotechnological and bioprocess strategies have been developed to reduce the process time and to enhance the quality of final biocompost product.  So, the objective of the present megaproject is to develop a bioprocess for fast production of enriched biocompost from different agricultural (Bagasse, rice straw,….) and municipal solid wastes using biotechnological approaches.

Performed work and Results

1. Biocompost from Municipal wastes

The objective of the present study was to develop a bioprocess for fast production of enriched biocompost from municipal solid wastes using a native microbial cocktail and cheap lignocellulosic biomass i.e. wood chips. The open-windrow composting experiments included (1) only municipal solid waste (C), (2) municipal solid waste + wood chips at 3:1 ratio (CW), and (3) municipal solid waste + wood chips + a microbial cocktail (10⁸ cells/kg), containing 11 native mesophilic and thermophilic bacterial strains (CWM).The microbial cocktail led to the fastest rise in the starting temperature (up to 73 °C after two weeks) and maximum carbon/nitrogen ratio decrease (40%) and organic matter reduction in the CWM compost. The CWM compost contained the minimum concentrations of the heavy and trace elements (i.e. zinc, copper, manganese, lead, nickel, chromium and cadmium) as well as Salmonella sp. and E. coli populations, whereas the control (C) contained the maximum contents of the heavy metals and human pathogens. The maximum and minimum germination of the garden cress seeds were observed for the CWM (97.5%) and the control (73.3%) composts, respectively. Moreover, in comparison with the control, 60–70% increase was achieved in growth parameters i.e. wheat dry weight, wet weight, stem height and root long when 10% CWM compost was used.

     B. Biocompost from sugarcane bagasse

The present study was performed to isolate and evaluate microorganisms with high hydrolase activity and involing in composting process of bagasse, and to optimize fast production of enriched biocompost from sugarcane bagasse using native effective microorganisms. To do this, a dynamic and controllable solid state bioreactor with 4 containers was designed to be used in the modeling and simulation of the composting process and for isolation of effective microorganisms in composting process. During the composting process, isolation and characterization of mesophilic and thermophilic microorganisms was performed using selective media and carbon sources, including xylan, CMC and cellubiose. From 200 bacterial, fungal isolates and actinomycetes, 60 isolates showed minimum 2 enzymatic activities. Following the quantitative experiments showed that 10 isolates show maximum hydrolase activity. To optimize bagasse composting process, Four native bacterial strains with high hydrolase activities were produced at their optimized fermentation conditions. The compost production experiments were performed in the format of completely randomized design (CRD). Bagasse, filter cake and vinasses were used as base materials in all treatments (exception for control). The microbial cocktail (106-107 cells/g waste), chicken manure or urea was used as improvers. The treatments were as follows: T1- chicken manure and microbial cocktail, T2-chicken manure, T3- urea and micronial cocktail, T4- urea, and T5- control (only bagasse). After establishing the composting system, different parameters, including C/N ratio, NH4, nitrate, phosphorous and potassium contents, pH and EC were measured every 10 days. Temperature was daily measured. The results showed that the maximum temperature increase (upo to 58°C), the maximum C/N ratio (15.9) and EC reductions was observed for T1, followed by T2. The highest phosphorous (1.1%), potassium (1%), total nitrogen (2%) and nitrate (210 mg/kg) and also the lowest ammonia (67 mg/kg) contents were observed in T1. Evaluation of the phytotoxicity effects of the produced composts on cress (Lepidium sativum) seeds germination showed that the fastest and maximum germination was observed for T1 and T2, respectively. The wheats cultured on the compost produced from T1 showed significantly higher height, and fresh and dry weights compared to other treatments. At the next step, the pilot production of compost was perfomed with two treatments (Control and T1). The results showed that in the T1, the temperature sharply increased during the first week of the process (more than 75°C), and after that it continuously decreased up to day 30 (50°C), whereas it was not significantly changed in the control. After 30 days, the C/N ratio was significantly decreased in T1 (about 40% reductions) whereas it was not changed in the control. Also, all physicochemical quality parameters, including nitrogen, phosphorous and potassium contents were significantly higher than that in the control. So, the results of the present study showed that the presence of microbial strains and chicken manure enhanced a significant reduction inprocess period, compost maturity and finally production of high quality compost from sugarcane wastes.

Future program

Isolation and chractreization of new effective microorganism (such as mesophilic and thermophilic bacteria and fungi) will be continued. Also, developing efficient bioprocess for other agricultural wastes such as rice and wheat straw will be continued.  

Scientific Achievments

• Technology transfer to Municipality of Isfahan (Contract No: 90/17663, Technology title: fast production of enriched biocompost from municipal wastes using native microorganisms)

• Patent:

​Pourmazaheri H., Salehi Jouzani Gh., Khayam S.M., Karimi Ebrahim, Tabatabaei M., Mirdamadian S.H., Ghanavati H., 2014, Fast production of enrcied biocompost from municipal solid waste and agricultural residues, Iranian Patent Grant number: 81653 (18-10-92).  

• Papers:
• Pourmazaheri H, G Salehi Jouzani, E Karimi, SMK Nekouei, M Tabatabaei, 2015, Development of a bioprocess for fast production of enriched biocompost from municipal solid wastes, International Biodeterioration & Biodegradation 104, 482-489 (ISI, IF:2.2)
• Sarkamarian F., G. Salehi Jouzani, F. Moradi, 2015, Optimization of fast production of enriched biocompost from sugarcane baggase using biotechnological approaches, Journal of crop Biotechnology,  No: 9, 49-64 (In Farsi)
• Pourmazaheri H., Rasouli Z., E. karimi, Salehi Jouzani Gh. Et al., 2013, Evaluation of enzymatic characteristivs of some native fungi isolated from composting process. The Journal of Modern Genetics,  8(1): 91-98. (In Farsi).
• Pourmazaheri H., Salehi Jouzani Gh. Et al., 2013, Evaluation of enzymatic characteristivs of some native bacteria isolated from composting process. The Journal of Agricultural Biotechnology,  5(1): 1-11. (In Farsi).