LISEP PACKAGES: HUGE VOLUME REDUCTION, WORKS WITH ANY SCREEN, CLEAN PROCESSED SCREENINGS, MAXIMUM ORGANICS TO TREATMENT AND EASY UPGRADE
LISEP packages process screenings from raw sewage flows. The efficient and effective process, takes raw screenings combined with a launder flow, washes and separates out the faecal matter and compacts the remaining screenings as a relatively clean and dry product ready for disposal by skip.
LISEP (liquid separator) Packages return the vast majority of faecal organic matter back to the main sewage flow for biological treatment, generating better sludges and preventing the starvation of biological filters.
LISEP packages can be used in conjunction with any screenings handling system fine or coarse. The modular design concept allows designers to integrate the package into any screenings handling site topography, placing the skip where it is most convenient. Haigh understands the implications of `whole life cost` (WLC) for operators and owners. With this in mind, the LISEP package optimises 'whole life savings' as a result of the process. Skip movements and the costs associated with disposal, by landfill, incineration, or other methods, are often the most significant costs in the day-to-day running of a sewage treatment plant. These costs are often neglected when selecting equipment; they can dwarf traditional WLC parameters. The substantial volume reduction achieved by LISEP packages means fewer skip movements and consequently lower whole life costs when compared to other systems. With increasing landfill costs and the legislative framework getting tougher the savings can only increase. Whole life savings equate to faster payback on capital spend.
Cost savings:
Lisep Packages reduce the volume of wet screenings by 90% without compacting - This is double the reduction offered by washing and compacting systems compared with competitor published data. So skip removal and disposal costs are halved. With Lipactors fitted the volume is halved again.
Layouts and Orientation:
LISEP packages are designed with two modules. A washing stage and a liquid separator / compacting stage. Washed and homogenised screenings are pumped from the washing stage to the liquid separators. This allows for a more convenient location of the skip without extensive launder or conveyor systems to carry wet screenings from the screen to the screenings handling plant. A myriad inlet works and building layouts can be accommodated using duty, duty standby or assist operating configurations.
Un- compacted Screenings:
Some installations may not need to take full advantage of the volume reduction offered by the compactors. For these applications, the compacting element can be left off the scope. The screenings handling plant will still be of the same clean quality but would be deposited as moist confetti in the skip.
Grit Capable:
Fine screens located upstream of traditional grit traps will invariably draw out grit as stones or fine grit out of the raw sewage flow. LISEP packages are designed to cater for grit, minimizing the impact on the operation and reliability of the plant. Automatic grit removal from the conditioning tank is available, or a manual solution exists for less grit prone sites via a bund.
Control Systems:
LISEP packages are designed to run automatically given a standard set of operating principles. The system is self-regulating to accommodate variable wash water supply for example during storm flows. Haigh has a full electrical control panel design and make capability. Packages can be supplied with or without integrating control systems.
HIGH PERFORMANCE SCREENINGS HANDLING FOR MEDIUM TO LARGE SIZED WASTE WATER AND SEWAGE TREATMENT WORKS
HOW IT WORKS
Screenings arrive into a conditioning tank via a launder flow channel from the screens. This can be a common launder or individual launder. Screenings handling are normally diluted using the screen wash water to provide the launder flow.
The level in the conditioning tank will rise to a preset start level, at which point the duty macipump(s) will start up. These are rated to beat the incoming launder flow so that the level in the tank will start to drop. The Macipump (s) will run until a preset stop level is reached and then change control to a 20-30 second run-on timer - this ensures that floating debris is drawn in or mixed and basically kept in suspension.
The Macipump is a disintegrator running on the same shaft as a centrifugal pump. Screenings are drawn into the pump through the cutterhead (headstock and shearplate design) so that the rag etc is disintegrated to a 10mm maximum particle size. They are then pumped away as a dilute mix (max 2% ds) to the liquid separating stage. In the solids disintegration and pumping action, the rag and paper is subjected to some severe agitation (washing) and greases, faecal matter are washed out of the rag, broken up and put into suspension.
Washed and disintegrated screenings are pumped into the liquid separator (LISEP) which uses centrifugal action to separate water from solids. The LISEP consists of a pair of conical sewage screens, with a rotor running inside but not in contact with. The rotor throws the dilute medium to the inner surface of the screen so that water and faecal matter is forced through (this decant liquor is piped back to the main channel or to a local drain point). The inner surface of the screen is swept clear by the rotor, moving the solids gradually up and out to the skip. There is a small compactor included on the discharge of the LISEP to further reduce the volume of screenings and to maximise dryness.
The LISEP can be positioned wherever convenient within 50 metres of the inlet with connecting pipework as required.
