Biodegradable plastic (BDP) bags could provide convenience to people who transport and discharge their kitchen waste in community composting devices located at community centers, shopping centers and other sites if the BDP bags could be deposited into the devices together with the kitchen waste. Before putting BDP bags into use, their degradability in such devices must be evaluated. One point of arguments is that some biodegradable fraction of waste may remain in the compost and this may suppress BDP degradation. The purpose of this research is to determine the effect of coexisting substrate on the BDP degradation in compost. Sheets that were cut from BDP plastic bags that are being sold commercially and are made of a PBSA and starch mixture were used as experimental materials. Starch was used as the coexisting substrate. The results of batch and intermittent experiments with different coexisting substrate additions showed that some high concentrations of coexisting substrates suppressed BDP degradation in spite of the presence of sufficient amounts of bacteria.

View full abstract

The production of animal feed from organic wastes has been brought to the attention of both waste suppliers and domestic animal farmers. Production of this feed can improve the recycling ratio of wastes and the self-support ratio of feed within Japan. Liquid feeding, in particular, has the advantage being effective for fattening, in comparison to dry feeding. However, raw materials for present methods of liquid feeding are limited to only some food by-products. The objective of this research is to investigate possibilities for utilizing those organic wastes that cannot be used as raw materials, as animal liquid feed. This was done by means of a hydrothermal reaction. The experiments were carried out under a 180-200
°C temperature range with a reaction time of up to 720min. Results show that organic waste samples, including rich protein that holds high value as an ingredient for animal feed, were soluble within 30min of reaction time. The proteins of feather waste were decomposed into a peptide with a low molecular weight under 1000Da. The digestibility of feathers treated with hydrothermal reaction was about 96%, which implies that liquid feeds produced using this method may also hold a high value as animal feed.

View full abstract

Previously, the authors used the lees of shochu, which is a Japanese distilled alcoholic beverage, as a medium to grow two mushroom species (Pleurotus eryngii and Pleurotus ostreatus) and produced mushrooms with a higher yield and higher value than conventional products at a low cost. However, during the mass-production of the mushrooms on the shochu-lee medium, the viscosity of the medium increased with the water content, making bottling of the medium using a conventional bottling machine difficult. In addition, it was necessary to develop a method for using the used shochu-lee medium to establish a local recycling system for shochu lees. In this study, the shochu-lee medium had a lower water content (58%) than that of the conventional medium (65%). In order to adjust the water content, a hole-making machine was developed to inject water (moisture). Next, a fermented total mixed rations (TMR) preparation was made from the waste medium and was evaluated in digestion and feeding experiments on sheep. The digestion rate was slightly lower in the waste medium group than in the control group. However, no significant differences in TDN and dry matter intake were found between the two groups. Therefore, fermented TMR with a waste medium content of 5-10% could be used to supplement sheep feed.

View full abstract