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Hanningfield WTP Essex & Suffolk Water. UK Water Supply Only Companies.

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Presentation on theme: "Hanningfield WTP Essex & Suffolk Water. UK Water Supply Only Companies."— Presentation transcript:

1 Hanningfield WTP Essex & Suffolk Water

2 UK Water Supply Only Companies






8 Essex Plants Chigwell Row: 90 ML/d –ozone: atmospheric pressure static mixer –18 slow sand filters (6 with GAC sandwich) 10 cm GAC on bottom Hanningfield: 220 ML/d Lever le Haye: 120 ML/d –slow sand (all sandwich) (no ozone) Langford: 60 ML/d –2 stage ozone (diffusers) Langham: 55 ML/d –ozone: pressurized static mixer –12 slow sand filters (10 sandwich)

9 Chigwell Row Plant

10 Langham Plant


12 Suffolk Plants Barsham –River Waverly –post GAC, no ozone Lound –lake source, no pesticides (no ozone) Ormesby –River Buer, pesticide problems –considered ozone, but ruled out in final design –8 GAC contactors








20 Hanningfield Dam Reservoir: 25,000 ML

21 Essex and Hanningfield Area

22 Raw Water DOC = 5-6 mg/L algae –blue greens are particularly troublesome formerly produced high levels of THMs –pre-chlorination phosphate = 2-4 mg-PO 4 /L

23 Treatment Train Pre ozone Flash Mix Pulsator Clarifier Pellet Reactor Softener Rapid Gravity Filter Intermediate Ozonation GAC Adsorption Chlorination

24 Ozonation Liquid Oxygen Feed –owned and operated by BAA (?) Three Degremont Generators –18 kg/hr each Dose: designed for 5 mg/L total, current application is much less –0.75 mg/L as pre –0.35 mg/L intermediate –no residual out of either tank –ceramic diffusers

25 Ozone (continued) Purpose –algae control –pesticide removal isoproturon: most importantly - works well –mecoprop, diuron, chlortoluone, 2,4-D also doesn’t work so well alone for atrazine or simizine –but concentrations of these are dropping anyway –THM control

26 Thermal Ozone Destruct

27 Rapid Mix Original tanks were too large –floc growth began before exiting tank –Coagulant addition to tank effluent

28 Coagulant Addition Addition on effluent weirAddition on effluent weir Ferric SulfateFerric Sulfate –6 mg-Fe/L Polymer (LT20)Polymer (LT20) –0.1 mg/L

29 Coagulation Removes phosphate –otherwise it would interfere with softening process

30 Pulsator Degremont design –3 m/hr overflow –upflow sludge blanket –draw and release on 40 s & 10 s cycle –0.5 meter draw up




34 Pulsator Sludge Removal Sludge draw off –four hoppers –valves opened separately on a cycle

35 On-line Iron Analyzer Measures total Iron –colorimetric method Purpose: to monitor floc carryover –usually mirrored by turbidity


37 Pumping Station From pulsator to softener

38 Lime Hoppers

39 Lime Saturator

40 Pellet Reactor Softener controllers

41 Pellet Reactor Softeners “Fast” alternative to precipitative softening –applicable to waters at 8 C or higher as temp drops below 6 C, Lime carryover occurs –most used for groundwater where there are now extreme low temperaturs –only a few others for surface water Leiden, Netherlands Use of sand accumulators –fine sand rises to to and stays there until it grows larger

42 Pellet Reactor Softeners Degremont Design –8 units x 30 ML/d each –5 minute contact (fast) –80 m/hr overflow at center of tank where sludge blanket is located Lime addition (48 mg/L dose ?) Introduction of Silver Sand –0.2 mm as clean sand –2-3 mm after accumulation of “chalk”

43 Pellet Reactor Bottom


45 Pellet Draw-off

46 Pellet Reactor Softeners Entry of water at bottom

47 Top of Pellet Reactor

48 Pellet Reactor Softener overflow

49 Pellet Reactor Softener Overflow weir

50 Pellet Reactor Softener Treated water flume

51 Pellet Reactor Softener Waste sand with “chalk”

52 Pellet Reactor Softener Effluent sand

53 Pellet Reactor Softener Sand conditioning

54 Rapid Gravity Filters Anthracite/Sand Air scour backwash –washwater returned to reservoir

55 Intermediate Ozone Entrance security system

56 Intermediate Ozone Liquid residual monitors –all read zero!

57 Intermediate Ozone A view through the observation window 3-chamber contactor ability to add peroxide at 4 points for atrazine control –not used


59 GAC Adsorption Top of contactors Norit carbon backwash every 12 days –just for “good practice”

60 Chlorinators Vacuum system

61 Final Disinfection Chlorination mostly –residuals 0.8 mg/L at plant effluent 0.1-0.5 at end of system –about 50 ug/L THMs –CT standard is about 20-30 for surface water (10 for groundwater) company standard, none imposed by DWI Post contactor ammoniation (summer only) –some nitrite problems need occasional chlorine pulse

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