بررسي اثر مواد افزودني طبيعي بر روي ته نشين پذيري لجن فعال

چكيده انگليسي :

AbstractWastewater controlling has became necessary in modern societies these days The activated sludgeprocess is the most common biological wastewater treatment method in the world The final aim ofbiological wastewater treatment is removal of dissolved organic matters Sludge bulking is one ofthe most common problems relateing to activated sludge wastewater treatment and this causespoor settling of sludge in secondary sedimentation tank Although very extended researches havedone on the sludge bulking this problem hasn t eliminated completely yet The natural additivesare materials that exist in the environmen and frequently enter the to the environment as solidwastes Assessment of probable influence of natural waste materials on the wastewater settlingproperties was the principal aim of this research Sludge settling problems exist in most wastewatertreatment plants in Iran and maybe using natural additives can be one of the solutions for bettersludge settling SVI is one of the operating parameters that used for secondary sedimentation tanksdesign and control A SVI value equal to 100 mL g is typically associated with good settlingsludge The ZSV is the settling velocity of the sludge water interface Vi at the beginning of thesludge settleability test Second phase of Shahinshahr Wastewater Treatment Plant was selected forwastewater sampling and conducting experiments of this research All experiments were done withthree iterations Experiments in this research conducted in four separated stages 1 determinationof optimum dosage for different natural additives 2 determination of zone settling velocity in pilotscale 3 determination of influence of sludge return on activated sludge settling properties and alsodetermination of some quality parameters in supernatan 4 determination of influence of differentmixing velocities and times on SVI values Natural additives used in this research includes maizestalk almond shell activated carbon coconut shell walnut shell hazelnut shell egg shell peanuthull silt and clay and pine bark SVI tests were done in a 1 Lit graduated cylinders Settlingcolumn used for determining of ZSV was a 200 cm high plexiglass cylender 190 cm of thiscolumn was filled with wastewater samples 20 cm diameter and 60 L volume Average values ofSVI for control sample was 823 mL g Optimum dosage for different natural additives is defined asthat reduced SVI to 100 mL g 88 percent decrease Average values of ZSV for control samplewas 1 222 m h Different natural additives increased ZSV of control sample to 2 to 3 times Thissignificant in ZSV is important because as a consequence of that the surface overflow rate OFR will increase 2 to 3 times too In this research influence of sludge return on activated sludgesettleability was also evaluated It was observed that this caused an improvement on sludgesettleability characteristics The results of jar tests shows that natural additives act as ballastingagents therefore this mechanism is the main responsible of decreasing SVI value of sludge

حسين لو، روح اله

بررسي اثر مواد افزودني طبيعي بر روي ته نشين پذيري لجن فعال

تصفيه بيولوژيكي فاضلاب , SVI