A Laboratory Study Of Anaerobic Treatment For Saline Organic Wastewater

In this dissertation, a laboratory study on the feasibility and degradation mechanism of anaerobic treatment for saline organic wastewater was conducted. The capability of resisting salt of anaerobic sludge cultivated by no salt or different salinity was comparatively studied. Moreover characteristic of salt inhibition to anaerobic microorganisms was deeply discussed and a dynamic equation was attained. During treating actual industrial wastewater such as Methyl-chloride wastewater in this paper, the capability of degrading organism of anaerobic sludge cultivated by no salt or different salinity was studied. Moreover, the feasibility of anaerobic treatment to practical saline organic wastewater in Upflow StagedSludge Bed (USSB) was studied too. The result showed:(1) Using artificial glucose wastewater, the salt inhibition to anaerobic sludge cultivated by no salt was increased gradually with influent salinity added from 0g/1 to 50g/l. But the activity of this sludge can acquire some recovery with the HRT prolonged. When the salinity was higher than l0g/1, the effect of the sludge cultivated by 20g/l salt was better than that by no salt. If influent salinity was the same as the cultivated salinity, the salt inhibition to this sludge was the lightest, increasing or decreasing influent salinity were able to inhibit the activity of the sludge and reduce the COD removal efficiency. Moreover increasing influent salinity brings heavier inhibition than decreasing it. The methanogenic bacterium was more sensible than acetogenic bacterium.(2) When the influent salinity was below 20g/l, salt inhibition type of anaerobic biodegrade glucose wastewater with sludge cultivated by no salt was anti-competitive with the inhibitor constant of 7632.2mg/L. The inhibitory dynamic equation was expressed as:When the influent salinity equaled to 30g/l, salt inhibition type was mix-competitive.(3) Anaerobic sludge cultivated by no salt or low salinity (such as 5g/l or l0g/1) was used to treat actual Methyl-chloride wastewater, salt inhibition was increasing with the influent concentration. When the wastewater dilute times 4.8 (COD 8300mg/L) , the total COD 9560mg/L, the sludge's methanogenisis activity can attain some recovery. Moreover, sludge cultivated by salt was less inhibited and the methanogenisis activity in this sludge was able to recover faster than that cultivated by no salt.(4) Anaerobic sludge cultivated by l0g/1 salt had much more well dephosphorus effect than that cultivated by no salt, especially used to treat high concentration of pesticide wastewater, The total phosphorus (TP) and organic phosphorus (OP) removal efficiency of this system could reach more than 45% and 55.6% respectively.(5) The microorganism form of anaerobic sludge cultivated by different salt content, compared with that cultivated by no salt, had a distinct change. With the wastewater salinity increased gradually, the microorganism form of anaerobic sludge changed from multi-microorganism system made up of bacillus and coccus etc. to microorganism system mostly made up of coccus. Moreover all coccus of this system had a definite thickness outer membrane.(6)The sludge in the USSB reactor had been cultivated for 60days at mesophilic condition (35 2 ), then was used to treat real organic wastewater. The result showed that the COD removal efficiency of the reactor could reach more than 80% and even reach 92.5% with influent COD concentration 2188~5288mg/L,organic loading rate 2.4~6.9 kgCOD.m-3.d"1. TP removal rate could also reach more than 50.5%, the ratio of bicarbonate alkalinity and VFA was among 3.33 ~ 5.73. The reactor had stable operation performance.