Valuable Uses of Sericulture Wastes
The Philippine Textile Research Institute (PTRI) of the Department of Science and Techonolgy(DOST) found various ways of utilizing sericulture wastes. When processed, these wastes can be a source of income.
Sericulture consists of three major aspects: moriculture, cocoon production and silk reeling. Moriculture involves the cultivation of mulberry plants to produce leaves used as food for silkworms, while cocoon production involves controlled rearing of silkworm to produce quality cocoons. Silk reeling, on one hand, involves unwinding of silk filament from the cocoon with raw silk as the end product.
In all these aspects of sericulture, a considerable volume of wastes is generated. Since the time when cocoon production was commercialized in the Philippines, only good cocoons were utilized. The wastes were unutilized due to the lack of appropriate technology on waste utilization.
Traditionally, leaves harvested from mulberry fields are brought to rear houses where silkworms are being reared. Leftover leaves from silkworm rearing bed are utilized as animal feed. After sorting, good cocoons are transported to the reeling facilities for production of raw silk, while defective cocoons are degummed for silk hand spinning. Pupae from reeling are utilized as fish feed and for extraction of oil.
In agriculture, sericulture wastes are found to have many uses. These wastes can be recycled and have high potential for. use in livestock, grain and fish production.
For instance, the wastes generated from silkworm rearing which include stems, small branches, undigested leaves, silkworm litter and skin shed during molting may be given to livestock as feeds.
Silkworm litter can also be processed into compost and fish feed, as it contains 3.06 percent nitrogen. Likewise, it can be an effective raw material (preferably fresh) for biogas production when combined with cow manure.
Stems cut from mulberry can be used as planting material, fuel and wood for carpentry and furniture as well as hand-made paper. On the other hand, mulberry fruits can be used for preparation of jams and jellies.
Defective cocoons, which are unreelable after all, can be used as raw material for silk handspinning after degumming. Handspun silk yarns may be used to produce clothing, linens, sweaters, bags, and ladies’ shoes. Cut cocoons and pierced cocoons can also be utilized as raw material for handicrafts like cocoon flowers, garlands, dolls, wall plaques, etc.
Silkworm pupa, which is discarded when reeling, is rich in protein and fat and makes excellent feed for fish, chicken, and cattle. Pupa also yields oil that is dark brown in color with fishy smell. The white fat obtained after hydrogenation is an excellent raw material for manufacture of hr-grade soap and candle. Sterol can be separated from this oil, which is a very good hair tonic.
Wastes generated from reeling, re-reeling, winding, throwing, and spinning can be utilized for the production of spun silk yarns. These are all high grade wastes and can be used to produce finer counts of yarns. After degumming, the waste is opened well and processed through a series of machines to convert the fibrous material into useful yarn.
The degummed silk wastes, when opened and handspun, produce a new textile material for use as weft in handloom and power loom weaving for novelty products such as placemats and fashion accessories like shoes and bags. It can also be used in yarn knitting for ladies’ blouses.
Spun silk is also used for shirting, shirting ties, scarves and curtain clothes. It can also be utilized for the manufacture of industrial belting and insulation of electric wires and cables.
To process silk and cocoon wastes into valuable products, PTRI has developed an optimized degumming and hands-pinning technology for these wastes. Degumming is the process applied to silk filament wherein the natural gum called sericin is dissolved to make them soft and easier to process for spinning. This also makes the wastes processable. The degummed silk wastes are then dried, opened and spun using a handspinning machine.
Another technology is the biss treatment of the pelade layers, one of the wastes from reeling. Biss is referred to as the continuous lap of silk waste which is formed after the pupae are removed from the thin shell through a biss treating machine. The biss is then washed, dehydrated and dried. It is then subjected through a biss hitting machine to make them soft. The end product is then processed through motorized opening machine and further processed as spun yarns.
With all the uses and the products that can be made -out of sericulture wastes, these wastes can actually be considered as wealth. As PTRI projects, it could generate livelihood in the community engaging in sericulture.