Sunday, 16 September 2012

Home Again

Back home after another successful course in the Gulf, this time on the use of membranes for water treatment in Qatar.

Both SCWO (Supercritical Water Oxidation) projects seem to be progressing well, undertook a site visit just before I went away for the UK one, and the European one looks likely to result in a treatability trial at least. I might produce a course on the technology if it looks viable/practical.

We are having a few problems with the Indian restaurant job, where extremely high levels of both grease and powerful cleaning agents are putting very high loads on the plant. We have recommended they use only agents with the EU Eco-label, as salesmen for cleaning products seem to be making slightly vague but nevertheless convincing green claims to our client. One to watch out for is: "Biodegradable to European Union definition of the term"- this is a pretty low standard, as I said in my correspondence with the consultants who employed me (acronyms explained below):

The EU standard for biodegradability of surfactants is >60% over 28 days HRT*, though this manufacturer claim that some of their products achieve >95% over 28 days.

This standard appears to be about biodegradability in the wider environment, rather than in the few hours of HRT in an ETP*. If we were looking to improve FOG* loss in the OWS*, we would need 95%+ removal in an hour or two.

Their degreasing products are mostly strongly alkaline mixtures of petrochemical based surfactants. They look to me to be pretty much standard heavy duty janitorial / industrial cleaners, similar to beer line cleaners.

I see no reference in their website or literature of the "septic tank friendliness" which their salesman claimed. There are many vaguely green claims made, especially by salesmen, so to make things easy for the client,  products in compliance with the requirements of the EU Ecolabel would be my desirable minimum standard. (A quick check of a couple of the salesman's products shows that their products do not all meet this standard (Their sanitiser has R50 substances well above specified limit)) Even this standard does not guarantee suitability, but it would improve matters.   

The products most likely to be causing the problems with FOG passing the  OWS, and to be likely to have biocidal effects are as follows:

Beer line cleaners
Degreasers
Floor cleaners
Dishwasher detergents
Toilet cleaners
Drain maintenance products

All of these should be the least aggressive product possible, close to neutral pH, and using the most biodegradable surfactants possible. The EU Ecolabel would be a useful guide.

Use of the lowest possible concentration of cleaning products to give an acceptable degree of cleaning is recommended, as is following the recommendations of the BW guide sent earlier."

The client is responding to our requests, and hopefully plant performance (whose improvement has stalled short of the required standard) will once again start to improve.  

Acronyms:
ETP= Effluent Treatment Plant
HRT = Hydraulic Residence Time
FOG = Fats, Oils and Greases
OWS = Oil Water Separator

And there's more - as well as bits and bobs of work for our long term repeat business clients (including something on foam suppression), we also have an order in the pipeline for treatment of a very interesting waste-water with unusually hazardous properties, and are starting the planning of a couple of courses in Oman and the Far East around the year end.

One more week of full-time consultancy before I'm back teaching at Nottingham. It's all about process design this year - I'm teaching it to all three years of the undergraduate course, and to most of the Masters' students too.  

Interesting to teach formally things you learned informally. First you have to figure out what you know and how you know it.

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