بازيافت ليوان هاي كاغذي يك بار مصرف با حذف لايه ي پلي اتيلني به روش آنزيمي و تبديل محتواي سلولزي آن ها به اتانول

Recycling an‎d bioconversion of the cellulosic content of disposable paper cups to ethanol

زيست فناوري

The increase in the production an‎d accumulation of solid waste due to rapid population growth, urbanization, an‎d technological advancements is a significant threat to the future of the world. Research is underway to explore the potential of using this waste for valuable products an‎d creating a circular economy. Disposable paper cups are difficult to recycle after consumption due to the presence of a polyethylene plastic layer an‎d are considered one of the problems of solid waste management. Separating the polyethylene film from the paper is an important prerequisite for recycling an‎d reuse of these cups. In this study, an attempt was made to combine the action of an enzymatic system (alpha amylase) an‎d mechanical force to separate the plastic an‎d paper layers of disposable paper cups, an‎d finally the conversion of the cellulose content of these cups into bioethanol was studied. The action of alpha amylase on the degradation of polyethylene has been previously proven, an‎d even partial degradation of polyethylene can help loosen its bond with paper. Commercially used alpha-amylase an‎d the results of Bacillus subtilis cell culture were investigated. First, by studying the factors affecting the separation of the layers, the optimal conditions for their separation, including the ratio of enzyme activity to the weight of the pieces cut from the glasses (shavings), the stirring speed (shear stress resulting from stirring as a mechanical force), an‎d time, were investigated an‎d carried out using Minitab software. The ratio of enzyme activity to the weight of the shavings was 0.14 enzyme units per milliliter to the weight of the shavings in grams (units of enzyme/mL.g), the stirring speed was 110 rpm, an‎d the time was 55 hours to optimize the separation of the paper an‎d polyethylene layers. Then, the obtained paper content, which is made of cellulose, was used to convert it into bioethanol. Enzymatic hydrolysis was used to convert cellulose into reducing sugars an‎d Saccharomyces cerevisiae yeast was used for the fermentation process, an‎d three separate hydrolysis an‎d fermentation modes, simultaneous hydrolysis an‎d layer separation with hydrolysis an‎d fermentation, were investigated. The concentration of sugar produced was measured using optical absorption an‎d ethanol by gas chromatography. The highest ethanol production efficiency from cellulose was obtained for the separate hydrolysis an‎d fermentation mode, which were 19% an‎d 49% for 24 hours an‎d 48 hours of separate fermentation, respectively. The results obtained in this study showed that processing paper cups using amylase enzyme can be a suitable method for utilizing the cellulose content of these wastes an‎d then saccharification an‎d production of bioethanol. The results of this study showed that the method used can provide a sustainable approach for managing disposable paper cup waste.

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