In the last few years the demand and production of meat has increased considerably with the increase in world population. The global meat production between the years 2016-2022 has increased from 317 million metric tons to 345 million metric tons. Poultry meat accounts for the highest percentage of meat production (41%), followed by Pork (34%), Beef (20%) and Lamb (5%). With this production comes its associated problems like greenhouse gas emissions from livestock , increased use of water, land and energy and the generation of waste materials from the slaughter houses. Slaughtering is the process of killing and butchering of animals for food. Slaughter house wastes consists of solid, liquid and semi solid materials that pose a threat to the environment. The question is how these wastes can be managed so as to promote Circular economy and minimize the impact on the environment.
Types of slaughter house wastes
Slaughter house wastes are waste materials that are inedible and are generated during the production and processing of meat from live animals. It may be solid, liquid or semi-solid material.
Solid waste
- Non edible organs
- Skin
- Dung
- Hairs
- Left over feed
- Bristles and Feathers
Liquid waste
- Waste water generated from the slaughtering and dressing operations.
- Blood released during slaughtering operation
- Urine
The animal by-products account for 60% of the live weight of the animal, out of which 40% are edible and 20% are inedible. For beef, pork and lamb the total by-products account for 10-30% of the live weight and for chicken it is 5-6% .
The waste materials generated from animal slaughtering are wholly organic and are chemically similar to domestic sewage but are more concentrated with dissolved and suspended material. These wastes should be treated, handled and disposed off properly as they can get contaminated with bacteria, viruses, fungi, etc.; that may pose a health risk to humans and animals. Also these wastes can pollute the water bodies when directly released into it.
How slaughter house wastes are handled during different operations?
After slaughtering blood generally goes down into the municipal drains thus causing pollution. Very few slaughter houses collects blood due to inadequate facilities. Blood can be used in the pharmaceutical industry. Also during dressing the skins that are removed are left on the floor due to lack of tools. During evisceration (The process of removing organs from an animal) the butchers generally throw the organs at the community bins; especially by those who carry out illegal slaughtering; thereby causing pollution.
Implementing circular economy
Circular economy is a model that implies reducing the amount of waste and reusing and recycling a product as long as possible thereby increasing the lifecycle of the product and keeping the materials within the economy. Efficient use of the animal by- products will have a direct impact on the economy and will minimize environmental pollution. On the other hand non-utilization of the by-products will lead to additional expenses for the disposal of the wastes and also loss of potential revenues, apart from its environmental and health effects.
Majority of the waste from slaughter houses are animal by-products which can be used to make many valuable products like leather, casings, bone meal, meat meal, gelatin, ornamental items etc. By-products can be classified as:
- Primary by-products: The by-products harvested directly from the animal (e.g.-Bone, blood. etc.).
- Secondary by-products: The by-products derived from primary by-products (e.g.- Gelatin from bone, leather from skin, etc.).
The by-products can be further divided into Agricultural by-products (meat meal, fertilizers, etc.), Industrial by-products (gelatin, glue, etc.), Pharmaceutical by-products (hormones, biochemicals, etc.). The table below shows different uses of the by-products:
| BY-PRODUCTS | USES |
| Blood | Livestock feed, Leather finishing, Blood sausage |
| Intestine | Sausage casing; Squash, Tennis and Badminton gut; Violin string |
| Bone | Handicraft items, Livestock feed, Fertilizer, Biodiesel, Gelatin |
| Bile liquid | Pharmaceuticals |
| Feathers | Livestock feed, Shuttle cock, Pillows, Quilts |
| Fat | Soaps and Greases |
The primary by-products should be collected and handled properly so that they can be used directly or for producing various other valuable products.
Treatment of slaughter house wastes
Solid Wastes
Biogas Production
The biomass wastes (paunch contents, dung, fat and blood) from a slaughter house can be processed in a plant for biogas production. Biogas can be used for power generation. This treatment is particularly applicable for large slaughter houses where large quantities of solid wastes are generated.
Composting
Wastes like blood, intestinal contents, hair, feathers, left over feed etc. can be decomposed naturally by the process of composting into bio manure that can be used as fertilizer in agricultural lands. It can be done at home also.
Rendering
Rendering is a process where the animal fat can be separated from the solids and water. All the inedible by-products can be processed in a rendering plant. The recovered fat can be used for making soaps and greases and also for edible purposes. The solid portion (meat meal or bone meal), can be used for making fertilizer.
Liquid Wastes
Waste Water
The waste water from slaughter houses contain many organic and inorganic pollutants which may pose a threat to the environment, if released directly into the water bodies. It should be treated chemically before releasing it into the nearby waterbodies.
Blood
Blood should be collected immediately after slaughtering to utilize its full potential, so that it can be used in the pharmaceutical industry. Proper drainage system should be provided to collect blood.
Urine
Good drainage system should be there to collect and make use of animal urine for medicinal purposes or as fertilizer.
Some of the efforts in managing waste
Many Non-profits, start-ups and individuals are working towards management and proper utilization of animal wastes.
Some examples from India are:
John Abraham, a veterinary doctor turned inventor from Kerala, has invented biodiesel from slaughtered broiler chicken waste and dead poultry birds. The biodiesel can offer mileage of over 38 km/l at around 40% of the current price of diesel and also it lowers pollution levels to a great extent. According to him 100 kg of slaughtered chicken waste can produce 1 liter of biodiesel. He got a patent for this.
Meat delivery startups like Easymeat.in, Freshtohome, and Zappfresh are working towards managing meat waste by providing fresh meat leftovers to restaurants and homeless people, recycling of the inedible by-products to produce organic manure and installation of analytics software to forecast orders in order to minimize waste.
Meat processing industries like HMA Agro Industries Private Ltd , is using the animal by- products in making food supplements and pet food.
Mudita and Radhesh, a start up, transforms chicken waste into handloom cloth, which is then used by tribal women and local villagers to craft accessories and clothes.
Likewise Keekonyoike , a startup in Kenya, in association with Kenya Climate Innovation Center (KCIC), have found innovative ways to convert the slaughter house wastes into biogas.
Conclusion
Reducing the production of waste and reusing and recycling it is the need of the hour. Slaughter house wastes can be managed by treating it properly and the non-edible by-products can be used for various useful purposes. It is important to educate the butchers about the harmful effects of disposing the waste without treating it, as majority of the butchers are less aware of this. Non-profits should take active steps in generating awareness and also in handling the wastes. Effective utilization of the resources will not only protect our environment but also benefit our economy by increasing the life cycle of the product, thus promoting circular economy. It will also increase the income of entrepreneurs and farmers.
Planet Rescue 101 