This paper explores the possibility of using an industrially processed municipal solid waste (MSW) for cellulase enzyme production via solid state fermentation (SSF) by Trichoderma reesei and Aspergillus niger. Both fungi grew well on the MSW substrate and production of cellulase enzymes was optimized for temperature, moisture content, inoculation and period of incubation. The effect of additional minerals, and alternative carbon and nitrogen sources were also examined.Following optimization a cellulase activity of 26.10 ± 3.09 FPU/g could be produced using T. reesei at 30°C with a moisture content of 60% with an inoculums of 0.5 million spores/g and incubation for 168 hours. Addition of extra nitrogen and/or carbon did not improve cellulase accumulation. Acid or alkali pretreatment of MSW led to reduced cellulase production. Crude enzymes produced from MSW by T. reesei were evaluated for their ability to release glucose from MSW. A cellulose hydrolysis yield of 24.7% was achieved, which was close to that obtained using a commercial enzyme. Results demonstrated that MSW can be used as an inexpensive lignocellulosic material for the production of cellulase enzymes. Research has revealed that T. reesei can produce 13.4 FPU/g cellulase activity using water hyacinth [8]; 154.58 FPU/g using sugar cane bagasse [10]; 8.2 FPU/g using oil palm empty fruit bunches [11]; and 1.16 FPU/g using rice bran [12] as substrates. Similarly it has been reported that A. Niger could produce 24 FPU/g cellulase activity using wheat straw as a substrate [13]. Other substrates such as banana peel, rice straw, corn cob residue, rice husk, banana fruit stalk, and coconut coir pith have all being used for cellulase production [14,15]. Optimizing Cellulase Production fromAlthough MSW can contain a high lignocellulosic content, there has been limited research into the use of MSW for cellulase production. Other research demonstrated the possibility of using MSW to produce cellulase via SSF. But by using raw not autoclave MSW [16,17]. In this paper, we report an example of using an industrially processed MSW for cellulase production and then the use of the resulting "cellulase cocktail" for the enzymatic hydrolysis of MSW. Materials and Methods Municipal solid wasteMunicipal solid waste (MSW) was kindly supplied by Wilson Steam Storage Ltd (UK). The MSW had been subjected to commercial steam 15 min, respectively. After autoclaving, samples were neutralized to pH 7.0 using either 1 M NaOH or 1 M H 2 SO 4 as appropriate. The samples were then centrifuged at 5000 rpm (4472 g) for 10 min. The solid fraction (pellet) was rinsed three times by adding distilled water to the pellet and re-centrifuged. The solid fraction was then dried overnight at room temperature. Journal of Fundamentals of Renewable Energy and ApplicationsMicroorganisms: Two filamentous fungi, Trichoderma reesei QM6a and Aspergillus niger N402 were kindly donated by Professor David Archer (University of Nottingham, UK). Procedures for storing and cultivating T. reesei and A. n...

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Heavy metals and metalloids, in sludge and sediments, are environmental pollutants of concern with long-term negative effects on human and ecological health. In this study, sludge from biological treatment of municipal waste leachate was pyrolyzed into leachate sludge-derived biochar (LSDB) at 300 C to 900 C, comprising complex organic and inorganic (particularly heavy metals) species formed from heterogeneous chemical reactions. Based on different advanced material analyses, that is, Thermogravimetric Analysis (TGA), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis, this study revealed that mass loss and microstructural changes of LSDBs occurred primarily due to decomposition of volatiles, aromatic rings, carbonates, and hydroxides. The leaching behaviors of heavy metals from LSDBs were evaluated using the Synthetic Precipitation Leaching Procedure (SPLP). The final pH in SPLP increased from 7.5 to 12.5 with pyrolysis temperature. The pH increase favored the retention of heavy metals in the LSDBs due to the formation of low soluble precipitates at alkaline pH. The heavy metals and metalloids in the LSDBs were present as surface precipitates due to precipitation and cation exchange rather than surface complexation. The leaching contents of metals and metalloids, such as Cr, Cd, Ni, Pb, and As, were all below their respective maximum discharge standards for the first priority pollutants in China. Practitioner Points• The pH increase favored the retention of heavy metals in the leachate sludge-derived biochar (LSDB).• The heavy metals in the LSDB were present as surface precipitates due to precipitation and cation exchange rather than surface complexation.• The heavy metals/metalloids concentration of LSDB (>600 C) in leachate was low and was likely safe for use.

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