A recent paper by ofwat details exactly the economic advantages for both the Utility provider and the farmer when using biosolids in place of manufactured fertiliser, it’s a shame the piece did not elaborate further on the carbon footprint of modern fertiliser production compared to biosolids but I’m sure that data is out there somewhere.
Sludge disposal costs are astronomical and often distances traveled are also excessive, simple Limesol treatment will cost £10-15 per tonne dry solids, treated Biosolids are attractive to agriculture as a valuable Nitrogen rich fertiliser alternative and can save the farmer considerable amounts of money!
In a nutshell;
Sludge disposal costs average £230 per tonne dry solids (TDS) in the UK
Biosolid cost to farm approx. £1.50
Allowing for Nitrogen content difference cost per hectare are;
The cost for treating a SAS Sludge to ‘Enhanced level’ with lime is approx. £10-15 TDS
Ref ‘Water 2020: Regulatory framework for wholesale markets and the 2019 price review Appendix 1: Sludge treatment, transport and disposal – evidence and design options ‘Water 2020 sludge treatment, transport and disposal