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Waste Water treatment world pulppaper82 a better adapted diet for the bacteria improves conditions for the biological degradation process. netFloc Lite treatment offers numerous benefits to biological treatment such as reduced P n and COD discharge. Figure 1. Typical flow sheet with A Primary sedimentation B Equalisation Anaerobic step C Active sludge D Secondary sedimentation E Tertiary treatment F Sludge treatment Figure 2. Particle size vs.degradation rate Primary seDimentatiOn Separation of suspended solids by primary sedimentation is often not effective at many pulp and paper mills. This leads to increased discharges of COD phosphorous and nitrogen into the recipient. Even with efficient separation some substances still have an adverse effect on the biological process which has to be taken care of. Bacteria are only capable of degrading small dissolved organic substances and have considerable difficulties with larger material and toxic substances from the wood or paper process. Therefore effluent fed from primary sedimentation to the biological treatment process often has an unsuitable composition. The larger fraction measured as suspended solids SS often simply passes directly through the primary sedimentation increasing the need for aeration and excess bio sludge-handling Figure 2. Treating the incoming primary effluent before the biological process highly reduces the high-molecular COD fraction leaving the low-molecular COD to be efficiently degraded in the subsequent biological treatment. Targeted types of additives such as those in the Kemira NetFloc Lite program will boost primary sedimentation performance thus retaining valuable prime-quality fibres and leaving only the low molecular COD for the biological treatment to degrade. Kemira NetFloc Lite is a cost efficient treatment that enables considerable improvements such as lower discharge of P N and COD and a decreased need for aeration. The application is simple and fast to install on the in-flow pipe with the treatment easily adjusted to give optimal results. Case stuDy netFloc Lite Enhanced primary treatment which improves conditions for the biological degradation process Grade Bleached Mechanical Pulp Challenge Mill wanted to lower WWTP operation cost and increase biodegradability. Especially production of bleached pulp grades was detrimental to the WWTP process stability solution Dosage of a special additive to boost primary sedimentation performance results More stable biological processes with lower P N and COD discharges to recipient Lower aeration cost Decreased amount of excess biological sludge to handle Reduced sludge dewatering costs and increased sludge energy value savings 20 total WWTP process costs saved including lower usage of energy and chemicals as well as improved sludge dryness BiOLOGiCaL aDvanCes Biological effluent treatment has for a long time been the state-of-the-art both in the pulp and paper industry and other sectors. The activated sludge process is the most widely used method worldwide. If operated under stable and favourable conditions treatment results are excellent with low concentrations of organic matter suspended solids and nutrients leaving the plant. The process is however sensitive to variations and disturbances4 and upsets are costly and difficult to predict and control. The effect of micronutrients on biological treatment has been studied by Kemira since the mid-1990s resulting in the development of the FennoNutri range of products. Ferric ions especially have a very positive effect on the microbial oxygen uptake and excess growth of detrimental filaments commonly found in the pulp and paper effluent plants. FennoNutri products enhance sludge separation and help bacteria to form more compact flocs Figure 3. Nowadays these products are used by many mills in some cases supported by small amounts of polymer in the secondary settling tank to prevent escaping biomass and decrease discharge values. Also in anaerobic treatment plants the usage of FennoNutri