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Downward movement of cadmium and phosphorus from phosphatic fertilisers in a pasture soil in New Zealand
1997
Loganathan, P. | Hedley, M.J. (Fertilizer and Lime Research Centre, Massey University, Palmerston North (New Zealand))
Effects of elevated CO2, nitrogen supply and tropospheric ozone on spring wheat-II. Nutrients (N, P, K, S, Ca, Mg, Fe, Mn, Zn)
1997
Fangmeier, A. | Gruters, U. | Hogy, P. | Vermehren, B. | Jager, H.J. (Institut fur Pflanzenokologie, Heinrich-Buff-Ring 38, D-35392 Giessen (Germany))
The influence of air pollutants on needles and stems of Scots pine (Pinus sylvestris L.) trees
1997
Kurczynska, E.U. | Dmuchowski, W. | Wloch, W. | Bytnerowicz, A. (Department of Biophysics and Cell Biology, Silesian University, ul. Jagiellonska 28, 40-034 Katowice (Poland))
Biological nutrient removal in suspended growth system
1997
Wisjnurapto, IR.
A series of experiments on biological nutrient removal using suspended growth bioreactor with a various reactor configuration have been conducted during the last five years. The first configuration applied a contact stabilization flowed by a denitrification processes in two sludge system. The two sludge systems mean that the aerobic sludge is recirculated in the aerobic circuit, and the anaerobic sludge is recirculated in the anaerobic circuit. The second configuration was conducted in a contact stabilization and denitrification processes in a one sludge system. The one sludge system meant that there are no separation between aerobic and anaerobic sludge; the aerobic and anaerobic processes are in the same circuit and all sludge are recirculated in the same circuit. The third configuration was performed in anaerobic-aerobic-anaerobic reactors and ended by the clarifier to clarify the biosludge before recirculated to the head of the circuit. This configuration was also using a one sludge system. In those three configurations, the hydraulic detention time in the reactors were varied from 2 to 6 hours, and the sludge age from 2 to 15 days. The results showed that the first configuration gave a very high performance in carbon and nitrogen removal. In terms of TOC [total oxygen concentration], the carbon removal achieved up to 92 percent or in terms of total COD [carbon oxygen demand] up to 80 percent, and 97 percent for total nitrogen removal. On the other hand, the phosphorus removal was only limited to the amount required for cells metabolism. More carbon removal were observed in the second configuration (94 percent of total COD) but less total nitrogen were removed (93), however, phosphorus were removed significantly (up to five times of the cells metabolism requirement). The best results in those three nutrients removal was achieved in the third configuration. No less than 95 percent of total COD and 96 percent of nitrogen removal were noticed, and phosphorus were removed at the level of more than six times of the cells metabolism requirement. The experiments concluded that the phosphorus removal was conducted by the aerobic microorganisms which are alternately treated in aerobic-anaerobic conditions. The degree of removal depended on how long the microorganisms were put in the aerobic and anerobic conditions. If the anaerobic condition was too long, the microorganisms would die, and no phosphorus removal took place. If it was too short, the removal would be less. For carbon and nitrogen removals in the system, the hydraulic detention time in the reactors and sludge appeared as the essential parameters in the process
Show more [+] Less [-]Ammonia stripping as a pretreatment for landfill leachate
1997
Cheung, K. C. | CHU, L. M. | Wong, M. H.
The effectiveness of ammonia stripping at different air flow rates (0, 1 and 5 L min⁻¹) and lime dosages (0 and 10 000 mg L⁻¹ calcium hydroxide) was investigated in aeration tanks in a laboratory as a pretreatment to remove ammoniacal-nitrogen and organic load (COD) in landfill leachate. Ammoniacal-nitrogen removal at 20 °C after one day was 70% for 0 L min⁻¹, 81% for 1 L min⁻¹ and 90% for 5 L min⁻¹ regardless of the origin of leachate. Ammonia loss was mainly due to desorption through water surface. The levels of phosphorus and COD were only reduced by lime precipitation, with 85% and 93% phosphorus removal and 24% and 47% COD removed for leachate from the Junk Bay Landfill (JB) and Gin Drinkers' Bay Landfill (GDB) respectively. The highly significant difference (P<0.05) of COD removal between JB and GDB might be due to the different age of the two landfills studied. Leachate quality and configuration of the treatment reactor were important factors affecting the efficiency of ammonia removal by stripping processes.
Show more [+] Less [-]Fluxes and mass balances of nutrients in a semi-intensive shrimp farm in north-western Mexico
1997
Paez-Osuna, F. | Guerrero-Galvan, S.R. | Ruiz-Fernandez, A.C. | Espinoza-Angulo, R. (Laboratorio de Quimica Marina, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico, Apdo. Postal 811, Mazatlan 82000, Sinaloa (Mexico))
Hydrochemistry of the aquifers in the Rio las Avenidas basin, Pachuca, Hidalgo, Mexico
1997
Huizar Álvarez, Rafael
Groundwater in the Rio de las Avenidas sub-basin corresponds to the bicarbonate-sodium and bicarbonate-calcium hydrochemical facies, which result from the mineralization of water passing through alkaline rocks (andesites) which prevail in this basin. However, the presence of high concentrations of Na⁺ and K⁺ reveals the existence of an external inflow of these elements: the registered mean values are respectively 94.3 and 19.0 ppm, with the Tèllez and Tizayuca areas standing out with reported values of up to 142 ppm. As for the concentration of soluble water cations, we find in decreasing order: Na⁺, Ca²⁺, Mg²⁺, K⁺, along with the anions HCO₃ ⁻, Cl⁻, SO₄ ²⁻, CO₃ ⁻, which combine to form the NaHCO₃, NaCl, Ca(HCO₃)₂, MgSO₄ and KCl salts. The presence of biological contaminants, P and detergents in the groundwater indicates that it may have been contaminated by waste water. In addition to the contaminants mentioned above, large quantities of Pb, B, Zn, Fe, Mn, Cr, Co were detected and although Fe, Pb, Zn, B, and Mn are closely related to the local lithology, the high concentrations of these elements along with the occurrence of Co, Cr, Cd, and Ni confirm the gradual degradation of the aquifers in the sub-basin. The water temperature indicates the existence of low temperature thermal processes in the area.
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