Sewage Sludge Reuse: Come On OFWAT the Time for an Open Market is Now

By Steve Last: Renewable Energy News

Beckton Sewage Works, London

We know that until quite recently what to do with sewage sludge was always a challenge for society. After all until the 1970's in the UK most conurbations were simply throwing it into the sea by the shipload. A disposal method which frankly seems cavalier in the extreme now, and would never be countenanced today, but only finally ceased in the late 1990s.

We now that it was a good move when the water acts of 20 years ago were passed it was good move to delegate sewage sludge disposal to the water industry and let the rest of us forget about it.

We know that the privatised UK Water Industry in its turn responded to that regulatory direction and developed a worthy system of dealing with sludge generated by sewage treatment operations, beginning initially with 'disposal' to local farmland and evolving into 'agricultural recycling' helped along by successive regulations defining treatment criteria and requiring control of added nutrients and contaminants.

However, the practical ability to do this depends heavily upon the quantity and quality of the sludge applied matching the needs of the economically accessible agricultural land such that many larger industrial connurbations have had to limit this practise. First landfill was used, but that option was largely closed by the EU landfill directive, which led to incineration as the most applicable solution.

But, all that has now changed with rising oil and coal prices. Like it or not renewable energy is here to stay, and for sludge and until something better comes along, that means Anaerobic Digestion.

And, a little publicised revolution is underway, in which the huge increase in sewage sludge production has occurred, as the consequence of the additional national sewage treatment now being applied nationwide, and society also happens from now on to need this as an energy source. It was, and to an extent still is now, a real problem finding ways to manage this sludge responsibly, but that HAS changed. Anaerobic digestion is the answer. It is there, it is proven, and the government is committed to subsidising it as an essential component of our energy policy which will allow the UK to comply with its 2020 renewables targets.

In other words; traditionally sludge has been considered a 'waste' requiring disposal, but that is rapidly changing.

A change in perception is obvious. Sludge is not going to be a waste any more, that is as certain as the fact that peak oil production has been reached, and that the days of huge fossil fuel resource discoveries has also passed. From now on sludge will have a resource value. A value which may be recovered through its use in the production of renewable energy, and primary feedstocks for chemical/ industrial processes.

The idea that only the Water Companies could be trusted with sewage sludge disposal, is now history. It simply isn't true. It's time to open up sewage sludge disposal to the market and allow the undoubtedly huge synergies which can then be realised between the Water Plcs and the UK Waste Management industry to flourish.

Examples of future synergistic relationships between the UK water industry and an open market in sewage sludge treatment include the large scale:

• co-composting of sewage sludge with municipal green waste,
• use of dried sludge as a substitute fuel in cement manufacture,
• growing of energy crops (fertilised by sludge) for renewable energy generation,
• co-combustion in power generation,
• production of lightweight aggregates from sewage sludge cake and other previously landfilled wastes.

If this was opened up further and Water Plcs could form joint-ventures with the Waste Management Industry, and the advantages to the nation would extend still further, by relinquishing land assets within UK cities for recycling and solid waste treatment, just where they are so badly needed close to where the waste which is produced and needs recycling.

Process all types of waste together at those sites which are now only Wastewater Treatment Works. These are sites which could so easily be further developed as integrated waste treatment sites, facilitating recycling as a natural adjunct to city life. Not something done in obscure industrial estates on the edge of conurbations to where the current generation of these plants are thrust, by "NIMBY syndrome effects" on our planning system and by so doing are incurring huge dis-benefits in traffic generation and transport fuel wastage.

So, OFWAT here this plea from Renewable Energy News! Open up the market for sludge and release the Water Companies from restrictions on them which were once appropriate, but now threaten the ability of the UK to fully develop the new integrated resource management infrastructure. An infrastructure, without which "zero waste" must remain a pipe-dream forever.