Show some energy

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It has been known for a long time that there is energy in wastewater. Nearly any wastewater has an energy value of 13-15 kJ/g COD. The organic matter present in wastewater is theoretically sufficient to more than offset all the energy used in its treatment. Continue reading

Food waste – down the bin, drain or in the soil?

I have just discovered a new fact about America. Most American households do not throw their kitchen waste in the garbage bin; they throw it down their drains. An interesting contraption installed under the kitchen sink called the garbage disposal unit captures the food waste, shreds it into small pieces (less than 2mm) after which it passes into the plumbing. Continue reading

Could we have the figures for leaking sewers, please?

Today, the concept of non-revenue water or NRW has become well-established for judging the efficiency of water utilities. The difference between water which is supplied to the network and the water which is billed denotes a loss of revenue that has come to be called NRW. Experts rightly declare that it is a misleading term and IWA has urged the use of Infrastructure Leakage Index or ILI to describe the efficiency of the real loss management of water utilities.

While ILI might need some time to take root, we do have the NRW percentages for countries around the world, for whatever they are worth. Thus, there is Malaysia with 41%, India with 40%, France with 27% (yes, the home of Veolia and Suez), Spain with 25%, UK with 23%, China with 22%, US with 11%, Germany with 8% and the only redeeming figure for Asia – Singapore with 5%.

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Municipal heart attack

Fats sewers

What happens when a city’s sewerage system gets a heart attack? Ridiculous proposition? Not really if you consider the amounts of fats, oils and grease (FOG as it is called) entering sewers nowadays. The global obesity problem is linked to it.Says Worldwatch magazine, “The rise of the fast food industry and the growing number of people dining out have had consequences for human and urban fat-processing systems alike, and there are ironic parallels between the metabolism of fat in human bodies and the capacity (or incapacity) of city waste systems to handle the increasing volumes of fat wastes”.

Around the world, sewer blockages and overflows are becoming more frequent because restaurants, bars and cafeterias are pouring their cooking residues into drains. Worldwatch says the volume of restaurant grease alone has reached 1.4 billion kg in the US. It would be interesting to have the figures for Asian cities. Continue reading