In the activated sludge process, activated sludge is separated in the secondary clarifier. The efficiency of the secondary clarifier with regard to solids separation depends, among other things, on the volume of wastewater fed to the secondary clarifier and, on the other hand, on the settling properties of the activated sludge. If a secondary clarifier is hydraulically overloaded and/or the settling properties of the sludge flocs have deteriorated, there will be a temporary or permanent increase in the amount of solids discharged.
Reliable compliance with effluent values
In conventional municipal wastewater treatment plants, the final settling tank is the last stage of the wastewater treatment process. The purpose of the secondary clarifier is to allow the activated sludge flocs and the finest suspended solids to settle and to discharge the clarified wastewater into the receiving water as free of solids as possible.
Increasing hydraulic loads and changes in the settling behaviour of the activated sludge are the reason why wastewater treatment plants often do not reliably meet today's minimum requirements for solids retention in the effluent.
An increased solids content in the effluent inevitably causes an increased COD, BOD and phosphorus load in the effluent. This in turn results in higher effluent charges and oxygen-consuming pollution of receiving waters.
Proven and reliable solutions for solids retention in the outlet of wastewater treatment plants
Reliable Solutions for Solids Retention
HUBER offers proven and reliable solutions for solids retention in the outlet of wastewater treatment plants. Depending on the requirements and general conditions, one of the following solutions can be applied:
Microscreening:
The HUBER Disc Filter RoDisc® consists of several rotatably arranged, disc-shaped microscreen elements. A filter cloth made of stainless steel or polyester from 10 μm is used as screening medium.
Sand Filtration:
The HUBER Sandfilter CONTIFLOW® is a deep-bed type upflow filter where the filter bed is cleaned without interrupting the filtration process. The filter medium is sand.
Cloth filtration / Pile cloth media filter:
The HUBER Pile Cloth Media Filter RotaFilt® consists of several rotatably arranged, disc-shaped filter elements. Particulate matter is reliably retained in the three-dimensional pile fabric structure.
In addition to the retention of solids, phosphorus elimination and micropollutant removal are playing an increasingly important role in the field of advanced wastewater treatment.
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