Reply To: Aylesford Paper Mills

I have been spreading bags of manure on the garden this afternoon and the smell reminded me strongly of the island site in summer, especially around by no 4 asp secondary clarifier if sludge had overflowed. This prompted a revisit to this site.

Regarding the island site and no 4 plant in particular, this was installed to handle the extra effluent when no 2 machine was converted to make fluting (later liner too). The new plant consisted of a prep plant to the east of the existing plants (3, 6A and 6B). The pulper was a side entry agitator Voith type (similar to the phase 2 de-ink plant hydrapulper). I don’t remember too much about the rest of the plant (cleaners etc) but recall the side entry agitators were prone to blocking up if baling wires were not all assiduously removed before bales of waste entered the pulper. No 2 plant was built at a slightly higher elevation than the others so the basement floor was usually dry, it also remained much cleaner that the earlier plants.

Outside, the effluent plant, comprised a deep sump and adjacent pump pit housing (I think) 3 pumps. The top of the sump was always covered by a thick crust of froth, fibre and plastic – mainly polystyrene packaging. The pumps fed no 4 asp primary clarifier – this was supplied by Portals Water Treatment Ltd (head office in Maidenhead, near my later place of employment). It was unusual in that the sludge extraction pumps were mounted on the rotating scraper bridge with their suction pipes led straight down into the centre anulus of the tank. This at least avoided the long suction  lines found under the base of many of the other clarifiers – very prone to blockage by thick sludge. Water from the primary was fed to the rectangular concrete asp tank (maybe via the concrete lined lagoon – my memory is hazy on this). The asp tank was aerated by two large paddles. Recycled activated sludge was returned via a concrete flume down one side of the tank. After treatment the cloudy water was drawn off to the secondary clarifier, sludge drawn off at low solids by two Archimedean screws and lifted up for either return to the asp or to be mixed with other sludges before dewatering on the Paxman filters (the centrifuges had long gone by my time). The Paxman filters were later replaced by Tassters, after my involvement with the water and effluent plant. The clean water from the secondary clarifier always looked the clearest of the island site, unless the sludge was bulking. Peter West was the mill chemist most involved with the monitoring and control of the island site asps at this time.

Regarding no 2 machine supply, after the closure of no 6, liner production  was switched to no 2, which used 6B prep plant (with its hot dispersion unit for the liner supply). No 3 plant was shut and 6A supplied no 3 machine. However, I recall that a fractionator was later installed on 6A plant and this perhaps was for liner stock, so I may have the use of 6A and B mixed up. Certainly towards the end of my time (c.1985) the old 3 plant and 2 plant were out of use.

Of the Paxman filters; there were 5 in all, 1-3 in the ‘Paxman House’ and 4 & 5 in the ‘Centrifuge House’. No 4 was originally belt discharge, the others string discharge, 4 was later converted after a period out of use – iirc the belt was prone to running off and difficult to clean. Dewatered sludge from either building was carried by conveyor to the gap between them, then led out to ‘jet throwers’ high speed conveyor belts with top nip rolls which ejected the sludge cake about 20′ into a partly enclosed area, whence it was shovelled up and loaded into a tip up lorry for dumping at Margett’s Pit (on the edge of the downs near Scarborough Terrace). Seagulls were often attracted to the piles of sludge and remarkably on one occasion I saw one ‘shot down’ as it were by a piece of cake flying from the jet thrower. It did not seem to be harmed however, just stunned and shortly got up and flew off.