We conducted an experiment to see how to effectively de-water sludges.
The sludge came from Northumbrian Water, from their drinking water treatment.
We were in communication with Debbie from Nature’s World in Middlesbrough. She is tasked with finding uses for glass shards, which come from recycling glass bottles. The glass can be crushed down to a variety of sizes, although there is plenty of dust, the shards are similar to sand. Although it could be argued that the glass is a more uniform size and not full of dust from unknown sources and qualities.
The method was to half fill an IBC tub with both gravels and glass shards. This was to act as a pre-filter to the reedbed. A delivery bag sat on top of the glass gravel filter for the collection and de-watering process.
The reedbed tub (seen in blue) was a nominal size to show the principle. The correct size for a particular flow would need to be established for a full sized system.
De-watering could take upto 14 days. It is entirely possible for there to be a number of tubs, filled in sequence, all feeding into the one reedbed. A 20m2 reedbed could filter between 1000 and 1500 litres per day, depending on concentrations.
Of course the glass and gravels can be washed and re-used. There may have to be materials replaced from time to time.
Further sludge de-watering is taking place, this time with minewater lagoon sludges. All results and data will be posted once we have them. However, the de-watered cake we have produced is so very similar to sludge from the chemical and centrifuge processes. As solid wastes these can now be disposed of easily. Therefore this method has a very wide application throughout industry.