| The paper studied on wastewater containing manganese from tailingproduced by beneficiation plant in phosphorus chemical company in Hubeiprovince. It took the method of coagulation andsedimentation-microfiltration to treat the wastewater and reuse it to thecirculating water system as supplementary water based on the analysis ofwastewater quality. In which way not only saves water, protects the waterenvironment, but also brings some environmental benefits, economic andsocial benefits.Experiments selected calcium oxide and polyacrylamide coagulation forsedimentation pretreatment. Single factor and orthogonal experiments resultsshow that the primary and secondary relationship between each factorsaffecting the treatment effect and the optimum combination conditions is asfollows: pH at10, the dosage of PAM is1mg/L, settling time is20min, thestirring speed is200r/min and stirring time is6min, under which conditionthe concentration of manganese ions in the water is0.28mg/L and removalrate of manganese ions is99.27%. Experiments results and theoreticalanalysis showed that chemical reaction of manganese ions and hydroxideions precipitate, the sweep netting and volume faction of manganesehydroxide generated in chemical reaction, adsorption and bridging faction ofadding coagulant and the certain coagulation effect of hydrous manganesedioxide produced by manganese hydroxide precipitate do great help to thetreatment effect.After the pretreatment by coagulation and sedimentation, it used themethod of microfiltration to treat the wastewater deeply. Throughconsidering the effects of water quality, sludge concentration, aerationintensity and the operating pressure on the removal rate of manganese ions,there came to the best technology for microfiltration: pretreating by calcium oxide together with polyacrylamide, sludge concentration is0.5g/L, theaeration intensity is0.15m3/h and the operating pressure keeping0.06MPa.By the method of microfiltration to treat the wastewater, the pH of thewastewater after treatment increased in a certain degree, the removalefficiency of turbidity is92.32%, the removal efficiency of COD is about20.97%, the removal effects of ammonia nitrogen is about2.18%, and theremoval effects of total hardness is1.73%. The quality of wastewater aftertreatment can meet the requirement of "recycled water circulating coolingwater quality standards"(HJ-T3923-2007).It was discovered from experiments comparison by the static rotarycoupon corrosion of carbon steel, stainless steel, brass and copper hanging inreclaimed water and tap water that the arrange order of corrosion resistancein descending is stainless steel, brass, copper and carbon steel. The corrosionrate of those four kinds of sheet metal hanging in reclaimed water are0.139、0.004、0.007and0.078mm/a respectively, while are0.114、0.001、0.001and0.034mm/a in tap water. The corrosion rate of those four kinds of sheet metalhanging in reclaimed water and tap water is little difference and can meet therequirements of excellent corrosion level, which indicates that thewastewater containing manganese after treatment can be used assupplementary water for circulating cooling water. |
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