Investigation to improve the coagulation process at Lillevik WWTP, Larvik
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- Master i teknologi 
Original versionKibiakova, H. Investigation to improve the coagulation process at Lillevik WWTP, Larvik. Master thesis, Telemark University College, 2014
Investigation to improve the wastewater treatment, focusing on the coagulation process, at Lillevik WWTP has been performed. Four activities were carried out for this purpose: 1. Investigate variations and correlations for all plant process data. 2. Study coagulation process in Jar test experiment. 3. Analysis of decentralized food processing wastewater treatment possibility theoretically and experimentally with biogas potential test and by economic feasibility estimation. 4. Theoretically evaluate the option of adding a biological contact process to the main treatment process. The existing data from the full scale plant since January 2012 show insufficient organics removal (measured as BOD and COD). It is seasonal and related to food processing wastewater, so local treatment of such was investigated. Local biological wastewater treatment can be efficient at a few companies to reduce COD inlet at Lillevik WWTP. Economic feasibility estimation suggests it as a reasonable solution. Jar tests using the coagulants presently in use gave consistent results showing that the method can be used to investigate chemical coagulation process improvements such as using different coagulants. The coagulation efficiency was reduced by the long distance from rapid mixing to flocculation. The chemical addition spot should therefore be moved closer to the flocculation. Adding a biological contact process to the main treatment process by aerobic treatment of the sludge reject water before it is returned to the coagulation appears to be an efficient measure. It can be a good way to improve the coagulations since active biomass can absorb dissolved organics before they are removed as sludge by coagulation. Since none of above mentioned measures alone is expected to enhance wastewater treatment as needed to always fulfil discharge requirement, integration of some of these solutions can be sufficient and should be further investigated.