Manufacture of organic fertiliser from poultry slaughterhouse waste rendering plant sludge using Delta-D technology

Abstract

Poultry slaughterhouse waste (PSHW) consists of, blood, feathers and other body parts of chicken (broilers) that cannot be sold or used for value addition. A few years back, this waste caused major disposal problems in broiler farms in Sri Lanka. The most popular disposal method that was adopted was to dump the waste in underground waste dumps, away from human settlements and water bodies. The highly nutritious, high protein high nitrogen, high phosphorous, leachate of these underground waste dumps caused pollution of soil and ground water and the surface runoffs sometimes polluted surface water bodies, such as rivers and lakes. With environmental laws becoming more and more stringent and the authorities becoming more forceful, most of the major chicken producers have installed Waste Rendering Plants (WRP), which convert PSHW into high protein poultry feed. However, WRPs have not been able reduce waste to zero, since, after separation of the solids as feed to WRP, there is a liquid effluent that has to be treated. Prior to sending this liquid effluent to activated sludge treatment plants, the suspended solids are skimmed out in Settling Tanks and Dissolved Air Flotation (DAF) Tanks and are called the Rendering Plant Sludge (RPS). RPS has around 30% solids and 70% water and cannot be composted or biologically treated due to its high fat content, which is more than, 10% on a wet basis and 33% on a dry basis. RPS cannot be incinerated too, due to the very high moisture content. Due to this difficulty, RPS is buried in lined underground waste dumps. The author undertook a research project, to convert RPS into organic fertilizer, using Delta-D Technology, for a leading broiler chicken producer, Nelna Farms, in Hanwella, in the Western Province of Sri Lanka in August, 2007. After appropriate laboratory research, a method was developed to digest the organic components in RPS, such as, collagen, fat and protein using the digestive fluid Delta-D, mixing with saw dust or agricultural waste to enhance the Carbon:Nitrogen Ratio to around 30:1 and finally neutralizing the mass with powdered dolomite and rock phosphate. The organic fertilizer produced was tested for around 1 year by applying to flowering plants, vegetables plots and tender and mature fruit plants and the yields were extremely satisfactory. In November 2008, the author carried out a demonstration on the process of manufacture at the Nelna Factory, in the presence of the Plant Manager (PM) and his staff and around 100 kg of organic fertilizer produced at the demonstration were handed over to PM for testing. The fertilizer was tested for around 1 year and in December 2008, the PM informed the author that Nelna Farms are planning to establish a plant to convert RPS into Organic Fertiliser using Delta-D Technology. This paper presents information regarding the process of Manufacture of Organic Fertiliser from Poultry Slaughterhouse Waste Rendering Plant Sludge Using Delta-D Technology.