Ammonia Nitrogen Concentration In Water Research Articles

Feature multi-level attention spatio-temporal graph residual network: A novel approach to ammonia nitrogen concentration prediction in water bodies by integrating external influences and spatio-temporal correlations

Accurate prediction of ammonia nitrogen concentration in water is of great significance for urban water quality management and pollution early warning. In order to improve the prediction accuracy of ammonia nitrogen concentration in water, this study developed a novel model based on graph neural networks called Feature Multi-level Attention Spatio-Temporal Graph Residual Network (FMA-STGRN). The FMA-STGRN model utilizes external influencing factors such as meteorological factors and point of interest data, as well as the spatio-temporal correlation information of ammonia nitrogen concentration between water quality monitoring stations, to accurately predict the concentration of ammonia nitrogen in water. The model consists of four main components: feature multi-level attention module, spatial graph convolution module, temporal-domain residual decomposition module, and feature fusion and output module. Through the organic combination of these four modules, FMA-STGRN can more effectively explore the complex spatio-temporal correlation relationships between water quality monitoring stations and more accurately integrate and utilize external influencing factors, thereby improving the prediction accuracy of ammonia nitrogen concentration in water. Experimental results show that the FMA-STGRN model outperforms other benchmark models such as RF, MART, MLP, LSTM, GRU, ST-GCN, and ST-GAT in various aspects. In addition, a series of feature ablation experiments were conducted to further reveal the key contributions of meteorological factors and point of interest data to the model performance. Overall, our research provides a powerful and practical tool for water quality monitoring and urban water management, with broad application prospects.

Removal of low concentration ammonia nitrogen enhanced by hydraulic cavitation combined with ozonation

The combination of hydraulic cavitation and ozone oxidation improves the removal efficiency of low concentration ammonia nitrogen. Focusing on the treatment of low concentration ammonia nitrogen wastewater (about 25mg/L), the study discusses the treatment effect of cavitation combined with different gases (O2, O3) on low concentration ammonia nitrogen. The treatment effect of ozone 3L/min combined with cavitation on ammonia nitrogen is 33.07%. The treatment effect of oxygen (3mg/L) combined with cavitation on ammonia nitrogen was 16.91%. At the same time, the treatment efficiency of ammonia nitrogen at different PH values was compared. When the initial concentration was adjusted from 7 to 10, the treatment efficiency increased from 33.07% to 84.55%. When PH=10, the ammonia nitrogen concentration in water finally dropped to 3.5mg/L, reaching the Chinese first-level emission standard (15mg/L). In addition, the mechanism of treating ammonia nitrogen in water by hydraulic cavitation combined with ozonation was discussed. The results show that ozone combined cavitation is very effective for the treatment of low concentration ammonia nitrogen wastewater.

Growth Performance, Body Lipid, Brood Amount, and Rearing Environment Response to Supplemental Neutral Phytase in Zebrafish (Danio Rerio) Diet

The present study was to evaluate the effects of neutral phytase supplementation on growth performance, survival ratio (SR), body lipid, brood amount, and rearing environment in zebrafish. The control diet was not supplemented phytase, and three levels of phytase (500, 1000, or 1500 U kg(-1)) was added to the three other diets (named as PP500, PP1000, and PP1500). Triplicate groups (twelve 100-L tanks) of zebrafish (initial mean weight, 0.284±0.012 g) were fed twice daily (08:00 and 16:00 h) to satiation for 12 weeks. The results showed that supplemental phytase in the diet improved weight gain (60.49%, 86.63%, 99.06%, and 111.88% in control, PP500, PP1000, and PP1500) and the specific growth ratio of zebrafish (p<0.05). Dietary phytase addition increased the whole body lipid content of zebrafish. The brood amounts (116, 123, and 124 eggs in PP500, PP1000, and PP1500) of fish fed with phytase-supplemented diets were little higher than the control (mean egg was 112). The ammonia-nitrogen concentration in water of fish fed with phytase-supplemented diet was significantly lower than the control. The nitrite concentration in water was also decreased in water of fish fed with phytase-supplemented diet. The SR was increased with the increasing of dietary phytase despite no significant difference was observed among each group. The present study first suggested that neutral phytase could be applied in the zebrafish diet. Furthermore, phytase addition increased the growth, body lipid, brood amount, and SR of zebrafish, and meanwhile decreased the ammonia-nitrogen and nitrite concentrations in rearing water.

Comparison of Phenate and Salicylate Methods for Determination of Total Ammonia Nitrogen in Freshwater and Saline Water

A study was conducted to compare the precision and accuracy of the phenate method and the salicylate method for determining total ammonia nitrogen concentration in water over a wide range of salinities. The two methods provided results that were highly correlated (P &lt; 0.01) as follows: freshwater, n = 29, r = 0.996; low salinity (≫4 ppt), n = 17, r = 0.994; high salinity (≫24 ppt), n = 11, r = 0.981. Considering all samples the regression equation for the two methods was Y = 0.939X + 0.0038 where X = salicylate method (mg/L) and Y = phenate method (mg/L); the r value was 0.984 (P &lt; 0.01), the slope differed from 1.0 (P &lt; 0.05), but the intercept was not different from 0.0 (P &gt; 0.05). In replicate analyses of the same samples, the salicylate method often gave a higher mean concentration of total ammonia nitrogen than was obtained with the phenate method. Also, precision was usually better for the salicylate method. Accuracy, as determined by spike recovery, was slightly superior for the salicylate method. The findings suggest that the salicylate method is a preferable alternative to the phenate methods for use in freshwater and saline water aquaculture applications.