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  1. ch81pc

    Sludge DS Meter

    Can anyone recommend a good low maintenance on line DS meter for use in sewage sludges 0-10% typical range? Many thanks
  2. ch81pc

    Removing Duckweed from a Clarifier

    Diquat is not a good idea as will remain active through your final effleunt and will get into the river and kill that too. Your duck weed will double roughly every 24 hours, so skimming will control but not eliminate your problem. If the weed is staying in the tank and not contaminating your...
  3. ch81pc

    Handling of dewatered sewage sludge

    We have used a live floor loading hopper taking 2x 30 tonne tippers at a time, which feeds into a twin covered auger. We do get some leaching from the belt, so be sure to have adequate draiange and wash down facilites. We dose quick lime into the twin augers and then pass into a plough shere...
  4. ch81pc

    Sodium Hypochlorite Gassing Off

    Off gasing and airlocks can be a major problem, especially if your plant is in an area with warmer temperatures, in which case you may need to chill your hypo to reduce the gasing. Normally I would do everything I can to prevent negative suction pressure with hypo. Are you using diaphragm dosing...
  5. ch81pc

    Sodium Hypochlorite Dosing & Calcium Deposits

    We use ion exchange No sludge.
  6. ch81pc

    Sodium Hypochlorite Dosing & Calcium Deposits

    We operate on softened carrier water on plants up to 160 Mg/d. Scale will form at the point where hypo meets unsoftened water forming calcium or magnesium carbonates due to the pH of the hypo - If your total hardness is <40ppm you shouldbe able to use un softerned carrier water without too many...
  7. ch81pc

    max residual for water main disinfection

    I've used up to 100ppm, but that was in a known problem main with a history of quality issues. In 98% of cases there is no need to go above the 25ppm.
  8. ch81pc

    Gas yield in anaerobic digestion - mass balance doesn't add up if calculating from COD

    Approximation is 2 cubic feet per person per day. But depends on freshness of the sludge. It's a good starting point though.
  9. ch81pc

    Typical Polymer Solution Strengths?

    Usually in the region 0.2mgl. If you don't have dilution water you need to approximate the polymer viscosity to that of the sludge to aid mixing. If your are dosing to raw water your batches should be in the around 0.05mgl
  10. ch81pc

    Waste water treatment facility

    Medcalf and eddy is a good start
  11. ch81pc

    Algae Growth in WWTP Clarifiers

    If circular clarifiers I use round road sweeper brushes sized to fit the channel. The bridge pulls them round. If you cut them in half to they can be sized to fit over the tops of the weirs and clean those too. Cheap and simple.
  12. ch81pc

    Wastewater lift station/forcemain problem

    Does the wet well operate at a higher level in the wet weather? If so higher suction head solves the problem. Maybe your problem is suction head rather than delivery? You can modify the suction pipework to reduce head loss, trim impellers on a couple of pumps or fit car's to over come the issue.
  13. ch81pc

    Water and Waste Water Treatment Design

    3pg + I +e where p is population equivalent g is water use per head I is infiltration (ground water leaking into old sewers) and e is industrial input. Typical values for each can be found on the web. diurnal flow typically varies 1.5 to 1.8 times the value over the day. Night time 3 am being...
  14. ch81pc

    World's largest service Reservoirs

    Honour oak works well on a 25% turnover each week. Might want to think about chloramination rather than super/de.
  15. ch81pc

    Flushing Water Mains - Scouring Velocity

    Without over engineering - 3 ft or 1 meter per second is the rule of thumb generally used.
  16. ch81pc

    Cumulative toxicity of chemicals

    Your best way to find out is to take a pilot scale sample of MLSS from your bio-ox and run it for a couple of days on your normal settled sewage spiked with the mix of hydrocarbon you mention. Run a second control vessel along side using your normal settled sewage.
  17. ch81pc

    Multimedia Filters Design

    How many stages or media types in your filter? Anthracite, courser sand, finer sand, gravel? Are you doing a collapsed pulse (combined water/air) BW or individual aire then water stages? If your leaking media, where is it appearing? It could be beign lost during backwash or else through damaged...
  18. ch81pc

    Secondary effluent filtration

    Misunderstood in thinking you were going straight from ASP to filter with no settlement in between. Assuming a post FST solids loading of 20mg/l + whatever your hydroxide loading will be, it will work without pre-settlement, but your washing will be increased.
  19. ch81pc

    Separation distance between potable water tank and sewage holding tank

    If they have to go in the same hole, dig the sewage tank lower so that TWL is below BWL of the pottable water tank.
  20. ch81pc

    Secondary effluent filtration

    Absolutely, settlement is a must. At normal RGF flow rates of 10m3/m2 per hour at a MLSS of 3000mg/l thats 30kg of solids loading per m2 per hour. Your filter will last a matter of minutes rather than hours between washes, especially if operating contact filtration through.

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