| A single rectangular horizontal flow secondary clarifier at Gold Bar Waste Water Treatment Plant was selected for study. Research was conducted to obtain a good understanding of the existing design and operation, in terms of activated sludge properties, sludge settling characteristics and hydrodynamics of the existing unit. Extensive literary study was conducted and based on the findings performance of the selected clarifier was evaluated. Clarifier operational problems like sludge rising and formation of density waterfall and density current were identified and appropriate recommendations were made. Attempt was made to establish seasonal trends on different physical properties and settle-ability of incoming sludge, return sludge and clarifier effluent. Different mathematical models, describing sludge settling velocity, were tested using batch settling data and the most accurate model response was reported. Existing design and flow distribution of the selected clarifier was studied and based on the acquired data a pilot-scale hydraulic model was designed and manufactured. The design of the pilot-scale unit was validated and the unit was prepared for further study and enhancement in design. |
