Assessment of runoff nutrients loss in Phyllostachys praecox cv. prevernalis forest land under simulated rainfall conditions.

The loss regularity of nitrogen (N), phosphorus (P), and chemical oxygen demand (CODMn) of runoff under different rainfall intensity and different management practices in Phyllostachys praecox cv. prevernalis forest land was studied. The total nitrogen (TN) and CODMn concentration in runoff were significantly correlated with the rainfall intensity under the three management modes named as control, fertilization, and cover. Moreover, N mainly lost in the form of nitrate (NO3--N). Generally, the relationship between total and dissolved phosphorus (TP and DP) loss in the three management modes was estimated in following orders: coverage > fertilization > control. The loss of P was mainly in the granular state, and the loss of DP only accounted negligible amount of the TP loss. The loss of CODMn was closely related to the magnitude of rainfall intensity. Results revealed that CODMn concentration in runoff under fertilization and cover management was significantly correlated with the rain fall intensity.

Development of model simulation based on BioWin and dynamic analyses on advanced nitrate nitrogen removal in deep bed denitrification filter.

A pilot-scale deep bed denitrification filter using quartz sand as the filter media was operated under filtration velocity of 5.23 m/h. Nitrate, nitrite, ammonia, and total nitrogen removal rates were relatively high at influent C/N ratios of 4:1 and 5:1. A model was developed using software to simulate the processes operating in the filter and improve the related parameters in the actual operations. The normalized sensitivity coefficient and the mean square sensitivity measure were used for the sensitivity analysis. Results showed that the stoichiometric parameters were the most sensitive, which were related to methylotrophs and biofilm. Measured data were consistent with the simulations. Moreover, the order of significance of factors affecting nitrate nitrogen removal was as follows: influent chemical oxygen demand, influent nitrate nitrogen, and hydraulic retention time. Last, the denitrification dynamic model was obtained at influent C/N ratio of 5:1.