Abstract

Development of a procedure enabling the continuous screening of partially degraded cattle hair from a process vessel float is described. Screen evaluation resulted in the selection of a 0.25 mm gap, rotary wedge wire unit. Hair screenability is retained by pre-depilation infusion of a reducing agent into the hair shaft. followed by sequential additions of lime. hydrosulphide and further alkali. A mercaptan-based reducing agent was selected as most appropriate, particularly in terms of avoidance of excessive toxic gas generation during soaking. Effluent quality improvements due to the process averaged: sulphide 96%, settleable solids 94%, suspended solids 59%, COD 42%, BOD₅ 36% and nitrogen 31%. Exploratory trials on the utilisation of recovered hair in poultry feeding are reported. Excessive mechanical action in the experimental process resulted in grain abrasion and process conditions require adjustment to avoid this defect.