Sewage Screenings Production

[sow]

Is there any reliable data for estimating the max hourly production of screenings at a sewage plant inlet works screening system?

I have figures of up to 0.03m3/1000 population/day (ciwem -uk) with peaking factors of up to 29 to get the max hourly loading of the works. However I this seems to be at odds with other sources.

Manufacturers of plant give widely varying estimates.

Further to this the addition of screens to storm outfalls, flat catchments and low gradient incoming sewers appear to make it almost impossible to estimate the amount of screenings produced from a sewage screening plant.

The only possible solution is to be very conservative with the specification of the kit, but its an existing works and space is an issue.

Thanks in advance.

 

[rcooper]

I have had a similar problem finding any useful information about screenings production. I have found figures of 45 g/m3 with a peaking factor of 3, 0.0218m3/1000pe/day with a peak of 0.27 m3/1000pe/day and a peak of 0.24m3/1000pe/day.

The problems with estimating screenings production comes about during storm conditions when street debris and washout from sewers and pump stations hit the screens. We have had screens taken out of service by dustbins and breeze blocks.

If it is an existing works, the best advice is to measure the existing screenings production. This will give you and average production, but not a peak production. If you are installing perforated plate screens instead of bar screens there is a correlation between the screenings collected by the two systems (Metcalf and Eddy).

If you are installing a standby unit, it may be possible to arrange for this to act as an assit unit in extreme loading circumstances, but as there is very little data about screenings production it is wise to be conservative.