Towards Purity is a documentary on the detailed treatment processes of water and sludge. A man is shown walking down a countryside lane. Rain droplets are seen bouncing onto a puddle; thunder crashes and a flash of lightning is shown. Title card - ‘Towards Purity’ overlaying the rain droplets on the puddle. Countryside landscapes are shown. A river is shown flowing through the countryside. Brooks, streams and lakes are shown. The sea is shown, and the clouds above it are emphasised....

Towards Purity is a documentary on the detailed treatment processes of water and sludge. A man is shown walking down a countryside lane. Rain droplets are seen bouncing onto a puddle; thunder crashes and a flash of lightning is shown. Title card - ‘Towards Purity’ overlaying the rain droplets on the puddle. Countryside landscapes are shown. A river is shown flowing through the countryside. Brooks, streams and lakes are shown. The sea is shown, and the clouds above it are emphasised. A field is shown. Rain on a house roof and gutter is shown, followed by a drainpipe. Water on the pavement/roads is shown. A reservoir is shown. Water pouring from a tap in a sink is shown. Water is shown pouring from a kettle into a teapot. Potatoes are shown being peeled in water and then being boiled in water. Plates are shown being washed in a bucket. A washing machine is shown in action. A man is shown washing his car. The water goes down a drain in the road. Someone is shown washing their hands in a sink of water. A toilet is being flushed. Water is shown splashing. A crane is seen moving loads in the distance. A bath of water is shown. The waste water goes down the plug hole. Water moving through a pipe is shown. A sewer being built is shown. Liquid waste pouring into sewage is shown. Sewage travelling to the river is shown, followed by a polluted river. A fish dying in the water is shown. Pollution entering the river is shown from the emergency overflow. A water treatment plant exterior is shown. A man in a lab coat at the treatment plant is shown. A diagram showing the purification of water stages is shown, including ‘floating matter screened’, ‘heavy grit settled’, ‘temporary storm water storage’, ‘lighter organic particles settled’, ‘biological purification’, ‘final settlement’ and ‘sludge drying’. A glass bottle of crude sewage water is shown. A glass bottle of ‘final’ water is shown. A graph showing the lowering of suspended solids and biochemical oxygen demand mg/l is shown. Exterior shots of the sewage works are shown. The screen house is shown, including the screening machinery in operation. Particles are shredded through large steel cutters. Water is shown continuing going through the screening process. The separation of grit and water is demonstrated in a beaker of water, where the grit dettles at the bottom. A ‘flow for treatment’ gauge is shown. Water is shown moving through structures of a parabolic cross section to keep the flow steady and constant. Water is shown travelling through a channel. The water being dredged and grit spilling out of the machinery onto a conveyor belt is shown. Water going through tanks and then a rotary scraper is shown. Water continues to flow through the treatment works. A storm overflow weir is shown. Water tanks emptying the storm overflow are shown. Removal of organic suspended matter by static settlement is demonstrated on laboratory scales. Water in settlement tanks is shown. A sludge hopper is shown. Circular tanks with radial flow and tanks with upward flow are shown. Workmen are shown. Sewage flowing over a weir is shown. A glass bottle is filled up with the water from the weir. A comparison of crude water and settled water is shown in the glass bottles. The suspended solids and biochemical oxygen demand graph is shown again. Different bacterial filters in action are shown. Microscopic biological organisms, including protozoa, from the water are shown. Large tanks at the treatment plant are shown. Waste products are shown in a further sedimentation process. Humus with a high water content is drawn off and is shown returning for treatment. Microscopic bacteria and protozoa are shown. Air introduced to the water by paddles is shown in channels. The aerating and mixing process is shown on a diagram. A spinning diagram appears, showing air, sewage and organisms all pointing to a central area. Several shots of the aeration process at the treatment works are shown. Aeration channels are shown. Bubbles of air in sewage and sludge are shown. Water passing over the weir to the river is shown. Control panels and water tanks in the treatment works are shown. A plaque on the pumps is shown, which says ‘Pumping Equipment by Lee. Howl. & Co. Ltd. Hydraulic Engineering - Tipton’. Sludge is shown pouring into water. Sludge in an oxidation ditch is shown, followed by the sludge going through a rotating steel brush. Sludge is shown pouring into the ditch. The glass bottles show a comparison of crude water, settled water, and final water. The graph showing suspended solids and biochemical oxygen demand now demonstrates a significant decrease. Water going through a micro-strainer is shown. Water going through more mechanisms at the treatment works is shown. A rapid gravity sand filter is shown. The control panel in the treatment works is shown. Water travelling out of the filter and onto the next stage is shown. Sludge is shown pouring out. A solid lump of sludge and a pile of soil-like sludge are picked up by a hand. A diagram is shown illustrating ‘volume change on drying’, which shows ‘as run on 95% water’; ‘as lifted 65%’ and ‘after stacking 35%’. Wet sludge pumping onto land to dry is shown. Landscapes of wet sludge are visible, followed by drying beds at the sewage works. Cry, cracked sludge is shown. Workers are shown shovelling up the dry sludge and slinging it into a truck. Dry sludge being lifted with machinery is shown, which then exits the works. The now-empty drying beds are shown ready for the next batch of sludge. Sludge being mixed with chemicals (including ferrous sulphate and hydrated lime) from chemical tanks is shown. A picket fence mixer mixes them together. A filter press is shown. A worker lowers some sheeting. Sludge continues to go through the filter press. A worker demonstrates the sludge cake on the filter tape. Wet sludge is shown collected on the outside of a rotating drum (with filter cloth). It is shown being removed from the drum at a discharge section. A rotating drum with steel coil is shown. Raw sludge is shown. A sludge digestion plant is shown. A sign is shown which reads ‘The Simplex Sludge Digestion Plant, Ames Crosta Mills & Co. Ltd. Heywood & London.’ A control panel and a temperature gauge are shown. Machinery in the sludge digestion plant is shown. Exterior of large tanks at the digestion plant. Exterior of the footbridge on the roof of the plant. A diagram showing the inside of the tanks and how they work is shown - sludge goes up through a tube and is discharged over the surface. Digested sludge is drawn off from the bottom of the tank. Microscopic protein and carbohydrates are shown. Sludge digestion tanks and machinery are shown. A control panel at the digestion plant is shown. A secondary digestion tank is shown, as a worker looks over the surface of it. Sludge being thickened in a consolidation tank is shown. Macerators are shown. A heat exchanger is shown. A temperature gauge is shown. A control panel is shown. An exterior of the sewage digestion plant. Sludge being pulverised is shown; the pulverised sludge leaves on a conveyor belt. A worker opens a furnace to reveal the pulverised sludge being burnt in the furnace. Sewage sludge is shown in a soil-like pile on a field. A man picks some of it up in his hand. Sacks of compost containing the sludge as soil conditioner are shown. Farmland is shown. People throwing bread to ducks in the river are shown. Two boys are shown dipping their feet in river water. People are shown travelling down the river on boats, and enjoying themselves. People are shown fishing in the river. Landscape shots of the river are shown. Credits - ‘A Beardsmore-Tucker Production for the University of Sheffield Department of Structural and Civil Engineering, Sponsored by the Institute of Water Pollution Control’ overlaying a river and a bridge. Credits - ‘and by Activated Sludge Ltd., Adams Hydraulics Ltd., Ames Crosta Mills & Co. Ltd., Dorr-Oliver Co. Ltd., English Electric Diesels Ltd., WM. E. Farrer. Ltd., Glenfield & Kennedy Ltd., Johnson-Progress Ltd., Jones & Attwood Ltd., Lee. Howl & Co. Ltd., Simon-Carves Ltd. (H. H. Division)., Simon-Hartley Ltd., Whitehead & Poole Ltd.’ overlaying a river and a bridge. Credits - ‘Facilities for filming kindly made available by the Institute of Water Pollution Control’ overlaying a river and a bridge. Credits - ‘Microphotography by courtesy of Water Pollution Research Laboratory (Crown Copyright Reserved) Dr B. A. Fry & Dr. J. Webster (University of Sheffield) overlaying a river and a bridge.. Credits - ‘Script and Technical Direction - Malcolm Clements & John O’Neill’ overlaying a river and a bridge. Credits - ‘Commentary - Howard Tucker’ overlaying a river and a bridge. Credits - ‘Camera, Sound, Editing and Production by Ken Beardsmore & Howard Tucker’ overlaying a river and a bridge.