Mr. Percy Foster:

The question on the removal of heavy metals is a good one and I will revert to the committee with information. I have not studied the area in great depth. The next question was on capacity with regard to composting versus anaerobic digestion. Each has its own merits. Anaerobic digestion has the potential to produce a biogas from which electricity can be produced. Having a consistent product like sewerage sludge is good because one must be careful not to shock an anaerobic digestion system with dramatic changes of feedstock. A way around this is to slowly introduce a new feedstock over time. I am not against land spreading across the board; what I am against is land spreading of untreated sewage sludge. The code of good practice states there should be no land spreading of untreated sludge. If sludge is treated to a certain standard by composting, lime stabilisation or drying, it can be land-spread.

The committee may not be aware of the study done through the EPA's STRIVE research programme on septic stank sludge and capacity. I believe the report will be concluded shortly and I look forward to seeing its conclusions and recommendations on how we can deal with septic tank sludge. After mobile dewatering one does not necessarily have to bring the dewatered sludge to a local authority wastewater treatment plant. It can be brought directly to a composting plant, a lime stabilisation plant, a drying plant or an anaerobic digestive facility. It can be diverted away from local authority wastewater treatment plants.