The Study On Long Term And Steady Biological Nitrogen Removal Of High Ca～(2+) High COD And High N Gelatin Wastewater

The typical gelatin production technique has main working procedure of degrease,washing and neutralization, pickling, lime and extracting glue. The contaminationmainly comes from lime procedure and washing and neutralization procedure whichform large amount of the alkaline wastewater for gelatin plant (1400t/t gelatin, pH>11)of high concentration of Ca2+( 800~930mg/L) and protein ( COD1000~2000mg/L,TN140-300mg/L). Presently, the treatment of wastewater for gelatin plant exist a few problems asfallow: ①It has few workingonreducingcontamination. ②It has few working and studying on nitrogen removal. The reported treated waterNH4 -N was still high (~140mg/L). + ③The specialty of gelatin wastewater is high concentration of Ca2+ and protein.The study on biological treatment of it was neglected because Ca2+ is nontoxic and mainorganic pollute is protein which is nontoxic too. Reported references were almost aboutengineer reports. The problem in biological treatment were not be found and solved.Biological treatment setting built by gelatin plant almost leave unused in china becausetreated water COD can't reach the emission standard. The reports about punishment ofgelatin plant were seen frequently in china. Aimed at above problems, following works were done in this thesis: ①The study on clean production technique about pollution reducing andwastewater reducing: The clean production technique of recovering calcium phosphate, which canreduce pollution for gelatin wastewater in pH and suspended COD has been proposed.Based on the seeing about wastewater amount and pollution resource, the forming oflarge amount wastewater of high concentration of Ca2+ and COD was demonstrated, Itwas founded that insoluble protein degrading by waste lime into soluble protein oramino acid would increase pollution, so the wastewater reducing technique of avoidingof above pollution increasing was proposed. ② The discussing, finding and demonstrating of key factors of biologicaltreatmentof wastewater for gelatin plant: The effect of two key factors, CaCO3 accumulating and lack of P on biological III英文摘要treatment of wastewater for gelatin plant was discussed and then found anddemonstrated by three experiments. At first, in isochronous domestic active sludgetreatment experiment, it was found that CaCO3 produced and accumulated by CO2combining with Ca2+ in the wastewater made that the treated water COD was difficultyto fall bellow 200mg/L. And then, the effects of CaCO3 accumulation and lack of Pwere confirmed by two repeated experiments of asynchronous domestic active sludgetreatment experiment done in autumn to winter and in spring to summer for 120 days. Itwas found by above two repeated experiments that: In initial stage of treatment experiment, because the lack of P not seriously, Nremoval was effective but not steady that a majority of treated water can reached thefirst emission standard of NH4 N<15mg/L but occasionally it over 50mg/L of the +-second emission standard. Because the lack of P turned more and more seriously withthe increasing of runtime, nitration turned more and more weak, and then disappeared inanaphase of treatment experiment ( >44 day in autumn to winter experiment, >77 day inspring to summer experiment) that treated water NH4 -N was over the second standard +of 50mg/L in anaphase. In initial stage of treatment experiment, the COD removal was effective thattreated water COD can reach the second emission standard of <200mg/L. But inanaphase( >53 day in autumn to winter experiment, >104 day in spring to summerexperiment), because the CaCO3 accumulation reached high( ~70% in sludge) and theserious lack of P that COD removal was not effective as before, the treated water CODwas difficult to reach the second emission standard of <200mg/L。 ③ The eff...