Thermophilic Anaerobic Method For Ammonium Sulfite Black Bamboo Liquor Treatment

Bamboo resources are abundant in the south of our country and quality of bamboo pulp paper is superior to straw pulp paper, so the bamboo is becoming one of the main raw materials of small paper mill. Thouth ammonium sulfite method pollute environment seriously, because of simple craft, it is adopted extensively in small paper mill. Small paper mill are prohibited but incessant. So it is important to look for a method to treat pollution of small paper mill. Thermophilic anaerobic treatment is a low cost method. But the method for ammonium sulfite black bamboo liquor treatment is reported little. The possibility of dealing with black liquor by thermophilic anaerobic method is studied.Based on the characteristic of black liquor and anaerobic sludge, black liquo(?) pretreatment and sludge acclimation are done and the effect of pretreatment are studied. The toxicity test of producing methane is done.The analysis result shows that the COD and BOD5 of black liquor are 27800mg/L and 7518mg/L respectively; the ratio is 0.27 that is close to critical value of biochemical treatment. The content of un-biodegradable lignin in COD is 56%, the concentration of ammonia nitrogen and inorganic sulfur compound is very high in black liquor. All these are disadvantageous factors of anaerobic treatment.The pretreatment that remove ammonia nitrogen and lignin from black liquor isstudied. When pH was 12 by adding Ca(0H)2, the flow time of N2 was 20min, the electrode method test result shows that removing efficiency of ammonia nitrogen was 74% and the ultraviolet spectrophotometry test result shows that degradation efficiency of lignin was 52%.Sludge is acclimated by compound of dextrose and black liquor. Experimental conditions are as follows: the range of the total concentration of COD was from 8000mg/L to 9000mg/L, the range of pH was from 7.0 to 7.5, initiative blending ratio and ultimately blending ratio of dextrose and black liquor was 10:1 and 3:1 respectively, acclimation time is 20d in the ultimate condition. The total acclimation time is 60~65d.The toxicity test of producing methane of ammonia nitrogen, sulfite, sulfate and black liquor are done. The result shows that the 50%IC of ammonia nitrogen, sulfite, sulfate, black liquor is 1009mg/L, 174mg/L, 10627mg/L, 4675mgCOD/L respectively. Concentration of nitrogen, sulfite and black liquor exceed 50%IC. It indicates the toxicity of black liquor is serious. But entering concentration may increase when sludge is adapted to black liquor for a long time.The effect of anaerobic treatment for pretreated black liquor is studied. When the time of anaerobic treatment is 3 > 6^ 9, 12d, the removing efficiency of COD and the cumulative methane production increase 57.4%, 67.9%, 143%, 169% and 38.8%, 39.5%, 89.5%, 104% respectively. The result proved that the pretreatment method is efficacious.In conclusion, it is possible to deal with the black liquor by thermophilic anaerobic treatment on condition that black liquor is pretreated and anaerobic sludge is acclimated for long time.