It's #TechnicalTuesday and Waste & Resources Consultant Graham Mustard and Business Development Manager James Ng are asking the important questions: How can Energy from Waste (EfW) operators look for extra efficiencies, minimise waste outputs and drive sustainability solutions?
The waste industry is focussed on driving sustainability and carbon reduction to achieve the Government target of net zero carbon emissions by 2050. The EfW sector can play a key part in helping the sector meet its obligations.
The operational optimisation of EfW plants can help in the reduction of its carbon footprint. With regular assessments and data capture spanning process operation, residues from combustion, including bottom ash (BA) and air pollution control (APC) residues, trends can be identified and early warning signs can be highlighted when the outputs fall outside the normal day to day operations.
With the introduction of the new BREF standards by the end of 2023, a key focus of the industry is nitrogen oxide and nitrogen dioxide (NOx) stack emissions levels. WRc have developed and assisted clients in the application of monitoring programmes to assess ammonia levels in the BA and APC residues. This can be used to identify possible overdosing of ammonia (or urea) and provides indicators for the operators to check their NOx abatement parameters and finetune the NOx capture process. Overdosing can result in ammonia emissions to the atmosphere (and the wasted cost of chemicals) and corrosion or blockage of components in the flue gas treatment system. Process optimisation therefore offers both environmental and operations benefits.
Further optimisations in flue gas treatment can be undertaken by analysis of the salt formation in the APC residues. The balance of salts of calcium chloride (CaCl2), calcium hydroxy chloride (CaOHCl), calcium carbonate (CaCO3), calcium sulphate (CaSO4) and free lime (CaO) can provide a snapshot of the performance and efficiency of the acid gas scrubbing process. Scrubber optimisation can then be used to reduce the amount of raw materials (lime) consumed during the process of acid gas treatment as well as reducing the overall volume of air pollution control residues generated.
WRc has developed advanced analytical methods to investigate onward recovery of the residue streams including BA and APC residues. In order to evaluate the effectiveness of treatment methods designed to allow for reuse of the residues, for purposes such as secondary building materials, speciation analysis can be utilised to support the most effective environmental recovery option.
The industry is putting considerable resources into ensuring compliance with increasingly stringent operational targets, WRc work hard to stay ahead of the game in terms of being ready to support testing and recovery programmes.