A review on spectroscopic methods for determination of nitrite and nitrate in environmental samples

Development of a simplified spectrophotometric method for nitrite determination in water samples

A new mechanism for the abiotic production of molecular iodine (I2) from iodate (IO3–), which is the most abundant iodine species, in dark conditions was identified and investigated. The production of I2 in aqueous solution containing IO3– and nitrite (NO2–) at 25 °C was negligible. However, the redox chemical reaction between IO3– and NO2– rapidly proceeded in frozen solution at −20 °C, which resulted in the production of I2, I–, and NO3–. The rapid redox chemical reaction between IO3– and NO2– in frozen solution is ascribed to the accumulation of IO3–, NO2–, and protons in the liquid regions between ice crystals during freezing (freeze concentration effect). This freeze concentration effect was verified by confocal Raman microscopy for the solute concentration and UV–visible absorption spectroscopy with cresol red (acid–base indicator) for the proton concentration. The freezing-induced production of I2 in the presence of IO3– and NO2– was observed under various conditions, which suggests this abiotic pr...

/pdf/nitrite-induced-activation-of-iodate-into-molecular-iodine-4uy2h4bgjk.pdf

Nitrite-Induced Activation of Iodate into Molecular Iodine in Frozen Solution

Rapid determination of ammonia nitrogen concentration in biogas slurry based on NIR transmission spectroscopy with characteristic wavelength selection

In order to improve the prediction accuracy of BP neural network model for chaotic time series,a prediction method for chaotic time series of optimized BP neural network based on genetic algorithm(GA) is presented.The GA is used to optimize the weights and thresholds of BP neural network,and the BP neural network is trained to search for the optimal solution.The efficiency of the proposed prediction method is tested by the simulation of several typical nonlinear systems and time series of real traffic ?ow.The simulation results show that the proposed method has better fitting ability and higher accuracy.

Chaotic prediction for short-term traffic ?ow of optimized BP neural network based on genetic algorithm

The invention discloses a method used for determining total nitrogen concentration in river water body via fluorescence spectrum. According to surface water classification, the lowest dissolved oxygen concentration is 2mg/L, so that relatively high dissolved oxygen concentration is needed to be maintained in surface water body restoration process. In polluted rivers, dissolved organic matters (DOM) are the main pollutants, when dissolved oxygen concentration of water body is relatively high, it is found via fluorescence spectrum scanning of DOM that correlation of fluorescence intensity of tyrosine analogs with high excitation wavelength with total nitrogen concentration is relatively high, and when dissolved oxygen concentration is 5.5mg/L, the correlation coefficient r =0.953, so that water body total nitrogen concentration can be determined rapidly via fluorescence spectrum scanning. The method is capable of solving problems of chemical determination method of total nitrogen concentration that time consumption and energy consumption are high, and secondary pollution is caused.

Method used for determining total nitrogen concentration in river water body via fluorescence spectrum

The invention discloses a constructed wetland treatment method for ammonia-nitrogen wastewater. Packing of a vertical flow constructed wetland A successively comprises a natural soil layer, a furfural residue layer, an oxygenation brick powder particle layer and a crushed stone layer from top to bottom, and canna is planted on the natural soil layer; and packing of a vertical flow constructed wetland successively comprises a natural soil layer, an activated carbon layer and a sepiolite layer from top to bottom, and iris is planted on the natural soil layer. Secondary constructed wetland treatment is adopted, ammonia nitrogen, total phosphorus and heavy metal ions are removed effectively, the crushed stone layer is placed at the bottom and prevents the constructed wetland from being blocked, and oxygen introducing is facilitated; the canna and the iris can effectively adsorb ammonia nitrogen pollutants, so that ammonium-nitrogen removal rate is greatly increased; and blockage can be prevented effectively while the adsorption efficiency of activated carbon is high.

Constructed wetland treatment method for ammonia-nitrogen wastewater

The invention discloses a method for efficiently removing phosphorus by a constructed wetland. A vertical flow constructed wetland is composed of an inflow pipe, an outflow pipe, a vent pipe, a filter layer of multilayer filler, a bottom watertight layer and aquatic plants having certain purifying function; the multilayer filler includes a sandy soil covering layer, a steel slag layer, an aeration brick powdery particle layer and a vermiculite layer sequentially from top to bottom; the constructed wetland of the invention is much higher than other methods in phosphorus removal adsorbing capacity and speed, service cycle of the filler is greatly prolonged, high exchange cost due to frequent filler exchange is avoided, the ability of a wetland system to degrade wastewater is improved, and the service life of the wetland is prolonged.

Method for efficiently removing phosphorus by constructed wetland

The invention discloses a treatment system for high-carbon-and-nitrogen wastewater. The treatment system for the high-carbon-and-nitrogen wastewater comprises a regulating pool, a lifting pump, a coagulative precipitation pool, a hydrolysis-acidification pool, another lifting pump, an IC (internal circulation) reactor, a two-stage contact oxidation pool, a secondary precipitation pool, a sludge concentration tank, a mud pump, a plate-and-frame filter press, a sludge reflux pump, a sludge outward transport cart, a reflux pump and a fan room, wherein the high-carbon-and-nitrogen wastewater passes through the coagulative precipitation pool to be subjected to pretreatment, so as to decrease the concentration of a water quality, and to reduce the treatment burdens of subsequent units; the hydrolysis-acidification pool intercepts non-dissolved-state organic matters in the wastewater and gradually converts the non-dissolved-state organic matters into dissolved-state organic matters, macromolecular sSubstances are converted into micromolecular substances, so that the biodegradability and the degradation speed of the wastewater are obviously improved, and the subsequent biological treatment is facilitated. The treatment capacity to a high-concentration COD (chemical oxygen demand) and the advantage of converting organic nitrogen into ammonia nitrogen are effectively improved by utilizing a novel anaerobic reactor IC reactor; the two-stage contact oxidation pool further degrades the COD and converts the ammonia nitrogen, the nitrogen removal by denitrification is realized, and discharge water is enabled to be up to a state-specified discharge standard.

Treatment system for high-carbon-and-nitrogen wastewater

The invention discloses a vacuum pump wastewater treatment system and a use method thereof. The treatment system comprises an equalizing tank, an elevator pump, an air floatation oil removal tank, a waste oil recovery tank, an aeration micro-electrolysis device, a two-stage bio-contact oxidation tank, a sedimentation tank, a water collection tank, an efficient filtration tank, a reuse water storage tank, a sludge tank, a plate-and-frame filter press, a sludge outward transportation truck, a water elevator pump, a reuse water pump, a sludge return pump, a sludge elevator pump and a fan room; waste oil generated by the air floatation oil removal tank can be treated and then is reused as a raw material; treated vacuum pump wastewater can be recycled to a vacuum pump system; aeration micro-electrolysis adopted in the invention effectively changes the biodegradability of wastewater to create favorable conditions for subsequent aerobic treatment; and the two-stage bio-contact oxidation tank can realize rapid starting and reach a treatment effect. The vacuum pump wastewater treatment system and the use method thereof have the advantages of good treatment effect, standard reaching of the quality of outlet water, small sludge output, realization of recycling of wastewater, and water cost saving.

Vacuum pump wastewater treatment system and use method thereof

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