Phenol, bacteria, Consett Coke ovens

An example from my personal experience: At Consett Coke Ovens one of the waste streams was phenolic liquor. Once-upon-a-time it would have been dumped down a disused mineshaft! We treated it in an activated sludge plant (loads of bacteria). Pretty amazing that it worked at all considering that the old name for phenol is carbolic acid and it’s a disinfectant which kills just about anything. We had a “spike” in phenol concentration (the plant was old, some of the processes had problems and the control systems were partly f*cked). As a consequence the bacteria “went to sleep”. They weren’t actually dead, but they weren’t active. As a consequence, even after the phenol levels returned to normal, the activated sludge plant no longer worked. We couldn’t treat the phenolic liquor, we weren’t allowed to dump it and we had only limited storage capacity. In these circumstances the official solution was to get a tanker load of sludge full of adapted bacteria from another coke plant. The nearest one with a suitable plant was in Sheffield (probably Orgreave). Cost at the time – several hundred quid. We chose the cheapskate option: buy a lorry-load of steaming, fermenting farm-yard manure and dump it in the sludge tank. Cost – 50 quid. After a short time (not more than weeks, and within the limits of the buffer storage capacity) the activated sludge plant was back and operating to specification. BTW on that plant they described having too much liquor as being “embarrassed” – as in “an embarrassment of riches”. A nice turn of phrase, with a touch of irony - “an embarrassment of sh1te”.

I doubt there are bacteria in nature which actively use phenol as a food source. Thankfully there isn’t enough of it around. There are undoubtedly bacteria which can tolerate phenol up to a certain concentration. The moral of the tale is that given the opportunity, within a very short time, bacteria can adapt to use something which is an outright poison to them (phenol) and not simply tolerate it, but use it as a food source. How they do it is not clear to me, but they certainly do. That is amazing and scary! The rubbish-dump programme was another example of the same.