|
SCREEN FOR WASTEWATER TREATMENT PLANT
Screens separate solid material from liquid streams. Wastewater is passed through a series of constrictions (the screen) and objects that are too large to pass through (screenings) are retained. Screens can be constructed from metal bars, metal mesh, wedge wire, perforated metal or plastic or polypropylene sacks. |
|
|
|
|
|
LAMELLA CLARIFIER
A Lamella Clarifier is used to separate organic and inorganic solids from liquid. The solid material, which is denser than the liquid, falls under the influence of gravity to the base of the tank, which is often sloping or conical, from where it is pumped away as a sludge.
|
|
|
|
|
|
SUBMERGED AERATED FILTER
A submerged aerated filter is designed to reduce the amount of BOD and ammoniacal nitrogen in settled sewage and industrial effluents. Aerated effluent is made to flow through submerged media which acts as a physical support for the growth of microorganisms. The media may be high voidage corrugated crossflow PVC, coarse sand, expanded shale, pozzolanic material or buoyant plastic. Submerged aerated filters can be seeded with bacterial cultures to accelerate start-up.
Submerged aerated filters can operate as mixed or plug-flow reactors. The effluent may flow downwards through one or more cells, counter-current to the rising air, or liquid and air may flow co-currently upwards and downwards through alternate cells. Air is introduced from perforated pipes, from nozzles or from fine bubble diffusers located below the media support structure. Submerged aerated filters have no internal moving parts.
With rigid plastic media the biomass is sloughed continuously and a settlement stage or a fine filtration system is required. Where inert granules or buoyant support is used, the effluent is relatively free from suspended solids but the biomass accumulates until a wash cycle is initiated. Then excess biomass is removed by air scouring or water back flushing or both. Wash liquors are returned to the primary settlement stage.
|
|
|
|
|
|
SUBMERGED MEMBRANE BIO REACTOR
Submerged Membrane Bio Reactor process is a suspended growth biological reactor integrated with a flat plate microfiltration membrane system. Essentially, the microfiltration system replaces the solids separation function of secondary clarifiers and sand filters in a conventional activated sludge system.
The SMBR microfiltration membranes are immersed in an aeration tank, in direct contact with mixed liquor. Through the use of a permeate pump, a vacuum is applied to a header connected to the membranes. The vacuum draws the treated water through the flat plate microfiltration membranes. Permeate is then directed to disinfections or discharge facilities. Intermittent airflow is introduced to the bottom of the membrane module, producing turbulence that scours the external surface of the hollow fibers. This scouring action transfers rejected solids away from the membrane surface.
The SMBR technology effectively overcomes the problems associated with poor settling of sludge in conventional activated sludge processes. The SMBR technology permits bioreactor operation with considerably higher mixed liquor solids concentrations than conventional activated sludge systems that are limited by sludge settling. The SMBR process is typically operated at a mixed liquor suspended solids (MLSS) concentration in the range of 8,000 to 10,000 mg/L. Elevated biomass concentrations allow for highly effective removal of both soluble and particulate biodegradable material in the waste stream. The SMBR process combines the unit operations of aeration, secondary clarification and filtration into a single process, producing a high quality effluent, simplifying operation and greatly reducing space requirements.
|
|
|
|
|
|
SLUDGE THICKNER
Sludge thickener is usually cylindrical. A picket fence is used to assist settlement and allow degassing and the removal of thickened sludge may be assisted by scrapers. |
|
|
|
|
|
