The Use of a Specific Actinomycete to
Degrade Cyanide Wastes
JOHN A. WINTER, Microbiologist,  Department of Limnology
Academy of Natural Sciences of Philadelphia
Philadelphia, Pennsylvania
INTRODUCTION
The disposal of wastes containing inorganic cyanides has been a problem for many years. Their presence in sewage plant influents upsets the
treatment processes and if still present in the effluents at any measurable level
are considered so toxic to the aquatic life of the receiving stream that regulations in Pennsylvania require that no cyanide be present in the effluents entering a stream (1).
The present means of disposal of cyanide wastes are chemical. Direct
oxidation with chlorine to cyanates, acidification and blow-off as HCN, and
precipitation as insoluble iron cyanides are among the most commonly used
methods.
All of these methods require (1) costly installation of process equipment,
(2) continual expenditure for chemicals and labor, (3) creation of a product
(cyanates, HCN, or iron cyanides) that must be disposed of, and (4) possibly
most important to the conservation ofthe Country's resources, require large
amounts of chemicals useful for productive purposes merely to be rid of a
waste material.
It is easy to understand, therefore, that the plating industry and all those
concerned with good management of the Country's water resources are very
much interested in improved means of disposal of these cyanide wastes.
This interest has led to the investigation of the use of biological processes
to destory waste cyanides. The advantages are evident: (1) After an initial
investment for the treatment unit, there are only limited costs for maintenance; (2) There is no problem of disposal of end products, for the cyanides
return to nature as microbial cells, and (3) There is possibility of inclusion
into future sewage treatment processes without too much difficulty.
The use of biofilters to treat plating wastes was reported by Brink and
Thayer in 1960 (2). After seeding vermiculite filters with mixed microbial
cultures previously acclimated to cyanide, they were able to reduce the
cyanide present at levels of 72 ppm ionic cyanide and 90 ppm total cyanide
by 100 per cent and 80-90 per cent respectively. Although these tests had to
be made batchwise with 24 hrs rest between passes and with cyanides supplemented by nutrient broth, the results were sufficiently promising for them to
continue their test program.
Trelawney et al. (3) reported the isolation of a large group of bacteria,
actinomycetes, and fungi that were able to utilize a cyanoacetate medium.
However, only one organism, an aerobic gram-positive bacterium was able to
use cyanoacetate as the sole source of carbon and nitrogen, and it was not
able to utilize compounds of inorganic nitrogen: potassium cyanide, thio-
cyanate, ferrocyanide, or ferricyamde.
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