Papers by Keyword: Active Barriers Capping

Abstract: Abstract: Active barrier system (ABS) capping zeolite with large surface area and strong adsorption ability is an effective way to control eutrophication of lake since it can remove ammonia in the lake released by sediment. Influence of the initial nitrogen concentration on eliminating nitrogen load of europhia sediment capping with active barrier system (ABS) were studied through an investigation of the repairment results of serious pollution period (total nitrogen concentration up to 25.33 mg/L), moderate pollution period (14.39 mg/L) and the slight pollution period (3.47 mg/L) of the ancient Canal of Yangzhou. The results showed that: (1) zeolite F1 inhibition effect is stronger than zeolite F2. More TN were removed as the initial TN concentration increased and longer rapid inhibit period were presented with the increased initial TN concentration. (2) The ammonia nitrogen in sediment could be rapidly released into the overlying water, and with lower initial TN concentration in source water, more ammonia would be released from the sediment. Long time treatment was necessary to inhibit the release of ammonia completely if the water showed a high initial TN concentration. (3) After covering zeolite, the total nitrogen in the overlying water were removed mainly through nitrification and denitrification. At the initial TN concentration of 3.47 mg/L, 14.39 mg/L, 25.88 mg/L, 61%, 45% and 52% of TN were removed by the conversion of ammonia to nitrogen gas, however, others left in water as nitrate nitrogen and nitrite residues, and 90% was nitrate nitrogen.

Abstract: Abstract: The application of an active zeolite barrier was investigated to improvement of eutrophication in the ancient Canal. For this, four types of zeolites (diameter: 1～2 mm) were applied in order to investage effect of the type of zeolite on N removal. The dosage of the zeolites was 1.46 kg.m-2 and the ammonium concentrations in overlying water were 3.47 mg/L. It is found that the capacity of elimination total N of the four zeolites was significant and decreased with the following order: Haiyu zeolite F1 > Aolin zeolite F2 > Natural zeolite F3 > Calcium zeolite F4. In addition, the results show that zeolite F1 and F2 belong to N inhibiting type as TN concentration of overlying water quickly reduced to 2.53 mg/L, 3.7 mg/L, and the corresponding removal efficiency of TN is as high as 56% and 35.6% after covering zeolite F1 and F2. The results indicated that the consumption rates of ammonia nitrogen in this system is greater than or equal to release rates of ammonia from sediment. However, TN concentration of overlying water still rise to high level (1.57 times of initial TN) when covering zeolite F3 and F4 (N non-inhibited type). Therefore, it is considered that the Haiyu zeolite should be the best barrier materials to clean sediment of the ancient Canal.