Preparation And Application Of Regenerative Conversion Degradable Films From Straw-Livestock Manure Mulch Fermentation Products

In recent years,organic solid waste,such as straw and livestock manure,has been increasing in China,causing serious impact on the human living environment.Currently,mulch fermentation technology is one of the most important ways to resource and reduce straw and livestock manure,and is being promoted by the Ministry of Agriculture and Rural Development.However,the membrane material used in the mulch fermentation technology has the problem of non-degradability,and the mulch fermentation products also have the problems of single product,low added value and poor marketing,but the mulch fermentation products contain cellulose,hemicellulose,humic acid and other substances,which can be used to prepare degradable membrane materials.Therefore,in order to broaden the utilization pathway of mulch fermentation products and increase their added value,this study decided to use mulch fermentation products as the main raw material,extract the film-forming components by alkali heat pretreatment,and coupled with film-forming additives such as sodium alginate,propanetriol,glutaraldehyde and sodium carboxymethyl cellulose to prepare a biodegradable film material by cast film formation.The membrane material was characterized and the film formation mechanism was investigated.In addition,the degradation analysis and application effect evaluation of the membrane were carried out,with a view to completing the transition from the R&D stage to the production application stage through small-scale simulation experiments,and eventually realising large-scale industrial production and environmental applications.The main findings are as follows:（1）The optimum membrane preparation solution was optimised by single-factor and orthogonal tests.The best membrane performance was obtained when the alkali concentration was 0.50 wt.%and the contents of sodium alginate,propanetriol,glutaraldehyde and sodium carboxymethylcellulose were 0.70 wt.%,1.00 wt.%,0.20wt.%and 1.00 wt.%.At this point,the tensile strength of the product was 16.88 Mpa,the elongation at break was 28.47%and the ammonia and carbon dioxide transmission coefficients were 1.23×10^-11 g·m·（m²·d·Pa）^-1and 1.03×10^-11 g·m·（m²·d·Pa）^-1.（2）The structural and morphological analysis of the membrane products by FTIR spectroscopy,XRD spectroscopy and SEM showed that there were interactions between the functional groups such as hydroxyl,carboxyl and aldehyde groups between the membrane forming additives and the membrane forming components of the fermentation products,and that a relatively dense membrane structure was formed through the synergistic effects of acetal reactions and intermolecular hydrogen bonding.（3）The membrane degradation analysis shows that the membrane material has good degradation properties.The degradation weight loss rate was fast in the first phase,reaching about 75%in 10 days.The degradation gradually slowed down in the later stage,reaching 79.97%weight loss in 31 days of experiment.Structural and morphological analysis of the membrane during degradation by FTIR spectroscopy,XRD spectroscopy and scanning electron microscopy showed that there was a breakage of hydrogen and molecular bonds during the degradation process,causing the membrane material to decondense.（4）The application of overlaid fermentation of straw and livestock manure using biodegradable membranes found that the membranes formed faster and had better durability as the membrane surface remained intact during the 35-day fermentation process.In comparison with the fermented product with and without the Gore film,the fermented product with the biodegradable film was found to have a higher organic matter and total nutrient content and a 100%mortality rate of ascaris eggs,which was better than the other two products.In addition,the quality of the product fermented with biodegradable film complied with the standard of Organic Fertiliser（NY/T 525-2021）and could be used as an organic fertiliser.At the same time,the cost of the biodegradable film was calculated to be much lower than that of the existing commonly used fermentation film materials,which has the value of promotion.（5）In this study,a biodegradable film material was prepared by flow-delayed film formation through the extraction of film-forming components such as cellulose,hemicellulose and humic acid from the film-covered fermentation products by alkali heat treatment,coupled with film-forming additives such as sodium alginate,propanetriol,glutaraldehyde and sodium carboxymethyl cellulose,etc.The film material has good mechanical properties and gas barrier,and the degradation rate is fast,with good realisation in the simulated application and good quality of the fermentation-covered The film material has good mechanical properties and gas barrier properties,and the degradation rate is fast.