EVALUATION OF PARAMETERS FOR THE DESIGN OF
ANAEROBIC LAGOONS TREATING FELLMONGERY
(UNHAIRING) WASTEWATER
Paul N. McFarlane. Lecturer
Biotechnology Department
Massey University
Palmerston North, New Zealand
Henryk Melcer, Project Engineer
Associated Water and Air Resources Engineers, Inc.
Nashville, Tennessee 37204
INTRODUCTION
Lagoons have become widely accepted as an alternative form of wastewater treatment.
However, the use of facultative lagoons to treat wastewaters containing significant concentrations of sulfide can create operational problems in terms of inhibition, odor and
color.   Sulfide concentrations as low as 4 mg/l inhibit some algae [1].
The Chromatiaceae, or purple sulphur bacteria, tend to predominate in overloaded
lagoons or those treating sulfide-bearing wastewaters [2,3].   They are phototrophic
bacteria, photosynthesis occurring only under anaerobic conditions and not involving
oxygen.   They are dependent upon the presence of oxidizable external electron donors
such as reduced sulphur compounds, molecular hydrogen or simple organic compounds.
Although their dominance in lagoons is often unintended, the ability of these bacteria
to oxidize reduced sulfur compounds under anaerobic conditions may be exploited in
the treatment of some specific wastewaters.   In New Zealand, this application is most
suited to the fellmongery (unhairing) industry in which hair or wool is removed from
animal skins prior to tanning by treatment with a lime-saturated solution of sodium
sulfide.   Subsequent washing of the treated skins produces a noxious, alkaline, sulfide-
bearing wastewater.
One lagoon system in New Zealand has satisfactorily treated a fellmongery wastewater
in this manner for some years [4]  but little data are available for the design of lagoon
systems using the Chromatiaceae to treat fellmongery wastewater.   These studies were
implemented to generate such data.
METHODS
Two, 88-liter model lagoons were constructed and operated according to the procedures outlined by Eckenfelder and Ford [5]  and Eckenfelder et al.  [6].   Figure 1
presents a side elevation of the model lagoons.
Data were collected using an experimental design which required six trials.   The
effects of temperature and sulfide concentration on the effluent quality were investigated
at the conditions indicated in Table I.   These values were chosen to simulate lagoon
temperatures in New Zealand and also to investigate the viability of treating segregated
fellmongery wastewaters containing high concentrations of sulfide.
479