Section Six
BIOLOGICAL:
ANIMAL AND DAIRY WASTES
22    RECOVERY OF PROTEIN, FAT AND OIL FROM
SLAUGHTERHOUSE PROCESS WATER WITH THE
DISSOLVED AIR CONCENTRATION PROCESS
Louis D. le Roux, Senior Sales Technologist
Jelte Lanting, Technology Manager
Biothane Corporation
2500 Broadway\Dwr # 5
Camden, New Jersey 08104
P. Borup Sorensen, President
The Aminodan Group
P.O. Box 43, Vestmole 1
DK-9990, Skagen, Denmark
ABSTRACT
This chapter discusses the Biothane-Aminodan (B-A) process which was developed for protein
and fat recovery from slaughterhouse process water where the recovered product is used as animal feed. The basic principles and techniques involved in protein and fat coagulation and floccu-
lation are discussed in relation to their removal with the dissolved air concentration system. Operating data of a full-scale protein, fat, and oil recovery installation at a poultry slaughterhouse is
also presented.
The B-A process uses FDA edible food approved additives for soluble protein and emulsified
fat coagulation and flocculation, as compared to metal salt coagulants and acrylamide based floc-
culants that are used in many dissolved air flotation systems for slaughterhouse wastewater treatment. The product recovered in the B-A system does not contain any toxic metal salts or cancer-
causing acrylamide and can safely be rendered into animal feed.
The B-A system uses dissolved air concentration (DAC®) water for protein and fat removal
from process water. During DAC® water addition, many small, homogeneously sized air bubbles
(=30 pm in diameter) are formed in the process water which attach to the floes. The air-floc particles have enough buoyancy to float to the surface of the concentrator. Only part of the recycled
water stream is used as DAC® water, which results in substantial savings in system operating
(energy) cost.
Typically, the overall BOD removal efficiency of the B-A system varies between 70 and 85%.
BOD removal efficiency is highest when process water soluble BOD consists mostly of proteins
and fats. More than 95% total FOG and suspended solids are removed from process water.
INTRODUCTION
Food processing companies generate an estimated 18 million tons of organic waste each year.1
These wastes consist mostly of unused raw agricultural materials, fermentation and microbial
residues, biosolids (biomass) and "float."2 Float, also known as skimmings, results from the
physical/chemical removal of proteins and fats from food processing plant wastewater (process
52nd Purdue Industrial Waste Conference Proceedings. 1997, Ann Arbor Press, Chelsea, Michigan 48118. Printed in
U.S.A.
215