Nitrate Waste Research Articles

Analyses and Retrospectives for a Profitable Agriculture

The work focused on assessing an overview of the agricultural economy in terms of the sustainability of agricultural systems adapted to climatic disturbances that allow ecological agricultural practices. Changing paradigms in agriculture with climate change involves adapting agricultural systems to the risks of using fertilizers in soil treatment, the interdependence of plant-soil water in agricultural practice, and the reduction of nitrate waste are also highlighted in the paper. Expectations regarding the reduction of greenhouse gases in the agricultural system have a long concern, what we propose in this study is that, at the same time, local traditions, the balance of the biosphere must be maintained with local nutrient needs based on climatic and soil characteristics. In the research, we analyzed some of the vulnerabilities, in the sense that, the agricultural practice and tradition must have a denominator in terms of fertilizers considering the risks of pollution or waste.

(Invited) Probing the Reaction Mechanism of the Electrocatalytic Reduction of Nitrate

The nitrogen cycle is extremely important for the environmental health of the earth. Anthropogenic fixation of nitrogen such as for ammonia production through the Haber-Bosch process is causing an imbalance in the nitrogen cycle as oxidized nitrogen species such as nitrate builds up. This nitrate pollution from agricultural and industrial waste poses an immediate threat to environmental and human health. Although there are numerous methods to treat this nitrate, the cost of treatment is often prohibitive, which could potentially be addressed by converting the waste nitrate to a valuable product such as ammonia, bypassing or minimizing the need for the challenging molecular nitrogen fixation reaction. In this work we discuss the use of electrocatalysis to convert nitrate to ammonia, where renewable electricity can be used to drive the reaction, minimizing the issue of emissions of carbon dioxide associated with providing ammonia. A major challenge with electrocatalytic nitrate reduction is decreasing the overvoltage of the reaction and increasing the reaction rate without losing faradaic efficiency towards the desired product. Through the use of kinetic studies, in situ spectroscopy, microkinetic modeling, and density functional theory calculations, we show how the adsorption energetics of nitrate and hydrogen can be used to understand the rates of nitrate reduction on metals and metal sulfide surfaces. We will discuss how X-ray absorption spectroscopy can allow us to probe the electrocatalyst surface under reaction conditions to identify the competing effects of nitrate and adsorption coverage and explain the potential-dependence of the reaction. We will also show that using adsorption energies as descriptors, we can use density functional theory to make predictions of new electrocatalysts with higher activity for nitrate reduction. By tuning the adsorption energies with alloying, as shown by alloying Pt with Ru to increase the nitrate adsorption energy, we experimentally validate our computational predictions, and show an increase in the rates of nitrate reduction at low Ru content. We also show that the nitrate reduction rate is decreased when the Ru content is too high, and nitrate binds to the catalyst too strongly, also confirmed by our computational predictions. Our measurements of the product distribution show that this alloying does not significantly change the high faradaic efficiency towards ammonia production (>90%). By comparing the electrocatalytic results to thermal nitrate catalytic reduction (i.e., using molecular H2 rather than an applied potential to reduce nitrate) we identify numerous similarities between electrocatalysis and thermal catalysis, but also specific factors unique to electrocatalysis that impact the rate of reaction. We will discuss how these may be used in the future to take advantage of electrocatalysis to produce ammonia from nitrate waste. Figure 1

Electrochemical Synthesis of Glycine from Oxalic Acid and Nitrate.

In manufacturing C-N bond-containing compounds, it is an important challenge to alternate the conventional methodologies that utilize reactive substrates, toxic reagents, and organic solvents. In this study, we developed an electrochemical method to synthesize a C-N bond-containing molecule avoiding the use of cyanides and amines by harnessing nitrate (NO3- ) as a nitrogen source in an aqueous electrolyte. In addition, we utilized oxalic acid as a carbon source, which can be obtained from electrochemical conversion of CO2. Thus, our approach can provide a route for the utilization of anthropogenic CO2 and nitrate wastes, which cause serious environmental problems including global warming and eutrophication. Interestingly, the coreduction of oxalic acid and nitrate generated reactive intermediates, which led to C-N bond formation followed by further reduction to an amino acid, namely, glycine. By carefully controlling this multireduction process with a fabricated Cu-Hg electrode, we demonstrated the efficient production of glycine with a faradaic efficiency (F.E.) of up to 43.1 % at -1.4 V vs. Ag/AgCl (current density≈90 mA cm-2 ).

Electrochemical Synthesis of Glycine from Oxalic Acid and Nitrate

AbstractIn manufacturing C−N bond‐containing compounds, it is an important challenge to alternate the conventional methodologies that utilize reactive substrates, toxic reagents, and organic solvents. In this study, we developed an electrochemical method to synthesize a C−N bond‐containing molecule avoiding the use of cyanides and amines by harnessing nitrate (NO3−) as a nitrogen source in an aqueous electrolyte. In addition, we utilized oxalic acid as a carbon source, which can be obtained from electrochemical conversion of CO2. Thus, our approach can provide a route for the utilization of anthropogenic CO2 and nitrate wastes, which cause serious environmental problems including global warming and eutrophication. Interestingly, the coreduction of oxalic acid and nitrate generated reactive intermediates, which led to C−N bond formation followed by further reduction to an amino acid, namely, glycine. By carefully controlling this multireduction process with a fabricated Cu–Hg electrode, we demonstrated the efficient production of glycine with a faradaic efficiency (F.E.) of up to 43.1 % at −1.4 V vs. Ag/AgCl (current density≈90 mA cm−2).

Uranium ions extraction from the waste solution by thiosemicarbazide anchored cellulose acetate

ABSTRACT The adsorption of uranium from nitrate waste solution was undertaken by the synthesised thiosemicarbazide functionalised cellulose acetate (TSCCA) adsorbent, which prepared via a condensation reaction of oxidised cellulose acetate (OCA) and thiosemicarbazide (TSC). TSCCA was examined using Brunauer–Emmett–Teller (BET) surface area analyses, Fourier Transformation Infrared (FTIR) spectroscopy, and Field Emission-Scanning Electron Microscopy (FE-SEM) characterisation approaches. The thermal analysis was performed through Therrmal Gravimetric Analysis (TGA) showing much stable chemical configuration at about ≥ 400 ◦C. Batch tests were conducted to assess the routine of TSCCA in uranium extraction. The influence of pH, the TSCCA amount, contact time, uranium concentration and temperature were scrutinised. The removal capacity of U(VI) after 90 min. using TSCCA adsorbent at 25 ◦C was estimated as 125 mg/g at pH 2. Langmuir and Freundlich adsorption models were evaluated for experimental equilibrium data. The Langmuir adsorption model was best fitted with experimental assessments. The kinetic data was analysed, and a pseudo-first order design was decided to fit all applications. The calculated thermodynamic parameters illustrates the adsorption of uranium ions onto TSCCA is endothermic, non-spontaneous and random. The regeneration efficiency of TSCCA was found to be 99% using 0.1 M Na2CO3. The removal efficiency didn’t change significantly when eight adsorption-desorption cycles were experimentally conducted.

Electrochemical removal of nitrate from a Donnan dialysis waste stream.

The objective of this work was to investigate electrochemical removal of nitrate from a high salinity waste stream generated by Donnan dialysis. Donnan dialysis for nitrate removal is a promising technique. It produces a distinctive composition of a high salinity waste stream of NaCl or Na2SO4 that requires a viable disposal method. The waste stream has the full anionic composition of contaminated groundwater, but the only cation is sodium. Experiments were conducted in a batch system setup. A copper cathode was chosen over brass, aluminum and graphite cathodes. A dimensionally stable anode (DSA), Ti/PbO2, was selected over a Ti/Pt anode. Electrochemical denitrification of high salinity Donnan dialysis nitrate wastes was successfully achieved, with different behavior exhibited in high salinity NaCl solution than in high salinity Na2SO4 solution. NaCl inhibited nitrate removal at high salinities while Na2SO4 did not. The maximum removals after 4 h operation in the high salinity wastes were 69 and 87% for the NaCl and Na2SO4 solutions respectively.

Palladium Isolation and Purification from Nitrate Media: Efficient Process Based on Malonamides

ABSTRACTSolvents based on malonamides have been described to be very efficient and selective for liquid-liquid extraction of Pd(II) from nitrate media. The present study details the possibility to selectively extract Pd(II) over common metallic cations, Cu(II), Ni(II), Co(II), Zn(II), Nd(III), Fe(III) and Al(III) using N,N’-dimethyl,N,N’-dibutyltetradecylmalonamide (DMDBTDMA) in toluene. The lowest selectivity was obtained considering Fe(III) and Nd(III), the extraction of all other cations being negligible. Pd(II) distribution and selectivity regarding Fe(III) have been fine-tuned using the aqueous HNO3 concentration as the sole parameter, so that extraction, scrubbing and stripping steps can be simply designed without the need for other specific metal chelating reagents and/or aqueous media and without the extensive generation of aqueous effluents. DMDBTDMA was also benchmarked with other classical Pd(II) extractants such as tributylphosphate (TBP), dihexylsulfide (DHS), tetraoctyl diglycolamide (TODGA) and bis(2-ethylhexyl)sulfoxide (BESO) in toluene and in n-heptane. Overall, this study reveals that malonamides are very well positioned and should be considered for further processing of aqueous nitrate wastes containing Pd contaminated with common base metals.

Aquaponic Integration and Automation – A Critical Evaluation

Aquaponics is technology developed from the aquaculture industry that integrates intensive farming of fish and utilizes plants (integrates hydroponics) in a continuous closed loop to clean the water for the fish. The plants clean the water of nitrate (waste form is initially ammonia) which has been converted into a form that is not toxic to fish by bacteria and is accessible to plants. Hydroponics technology is a technique used to grow plants and vegetables that does not incorporate soil, but nutrients that are dissolved in water and plants are either floated or treated with a nutrient film delivered to the roots by a variety of processes. These technologies are becoming more popular with communities and governments as the preservation of water becomes more of an issue in environments where water is becoming restricted in supply and has to be supplemented by mechanical means such as desalination, which comes at additional cost to consumers. The technologies have had a great amount of research interest to find parametres and ranges that the systems require to function successfully yet also remain productive with certain crop varieties. The successful diversification of crop varieties could increase the viability of commercial aquaponics, which could be achieved with the use of optimized advanced process control strategies.

Chemical recycling of cellulose nitrate waste

A chemical degradation technology for processing cellulose nitrate (CN) waste with any initial moisture content, which provides a high level of process safety, has been developed. Under exposure to chemical reagents, CN waste is converted to fireproof water-soluble nontoxic biodegradable products. Regression equations to relate the reaction conditions and the degree of degradation of CN have been derived.

Thermoanalytical investigation of the reactions causing the transuranic waste drum breach that occurred in the Waste Isolation Pilot Plant

In February 2014, an energetic gas-producing chemical reaction occurred in remediated plutonium processing waste emplaced in the Waste Isolation Pilot Plant causing the drum’s seal to fail and release radioactive material into and outside of the plant. This article provides results of our probative study using simultaneous thermogravimetric and differential thermal analysis and accelerating rate calorimetry to determine the thermal sensitivities of selected simulated characteristic remediated wastes such as hydrogen- and hydrogen, metal-triethanolamine nitrates and nitric acid solidified and stabilized with wheat-based pet litter. These studies found that these nitrate wastes were chemically unstable and susceptible to gas-producing thermal runaway reactions. If undried or partially dried, self-sustaining or accelerating-exothermic reactions were delayed in nitrate- and organic-containing materials to above 100°C while air-dried nitric acid and pet litter began self-heating exothermic reactions near 30°C that led to thermal runaway. Caution must be exercised when managing nitrate-containing wastes.

Extraction of zirconium from simulated acidic nitrate waste using liquid membrane in hollow fiber contactor

Extraction of zirconium from simulated acidic nitrate waste using liquid membrane in hollow fiber contactor

Utilization of cellulose nitrate waste

A two-step procedure for utilization of cellulose nitrate waste accumulated at industrial enterprises of the Russian Federation was suggested and experimentally checked. The procedure involves hydrolysis of cellulose nitrate in alkaline medium and incineration of hydrolysis products. The best reagents for complete hydrolysis of cellulose nitrate are aqueous solutions of sodium hydroxide and sodium carbonate. As demonstrated by thermal analysis and thermodynamic calculations, incineration of cellulose nitrate base hydrolysis products can be performed without using hydrocarbon fuel.

In the Lab: Uranium Capture From High Sulfate and Nitrate Waste Streams with Modified Silica Polyamine Composites

In the Lab: Uranium Capture From High Sulfate and Nitrate Waste Streams with Modified Silica Polyamine Composites

Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors

A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420mgL(-1) nitrate-N (2710mgL(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420mgL(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354mgL(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420mgL(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy.

A Review on Alternative Carbon Sources for Biological Treatment of Nitrate Waste

Huge amount of wastewater containing nitrogen is produced by various chemical and biological industries. Nitrogen is present in the form of ammonia, nitrate and nitrite. This review deals with treatment of nitrate based effluent using biological denitrification. Because of its adverse effect on aquatic life and human health, treatment of nitrate bearing effluents has become mandatory before discharge. Treatment of such wastes is a liability for the industries and incurs cost. However, the economics of the process can be controlled by selection of proper method and reduction in the operating cost. This paper reviews the advantages and disadvantages of different methods of nitrate removal with emphasis on biological denitrification. The cost of biological denitrification is controlled by the carbon source. Hence, use of alternative carbon sources such as agricultural wastes, industrial effluent or by products is reviewed in this paper. Policies for reducing the cost of nitrate treatment and enhancing the efficiency have been recommended.

Denitrification of high strength nitrate waste from a nuclear industry using acclimatized biomass in a pilot scale reactor.

This work investigates the performance of acclimatized biomass for denitrification of high strength nitrate waste (10,000 mg/L NO3) from a nuclear industry in a continuous laboratory scale (32 L) and pilot scale reactor (330 L) operated over a period of 4 and 5 months, respectively. Effect of substrate fluctuations (mainly C/NO3-N) on denitrification was studied in a laboratory scale reactor. Incomplete denitrification (95-96 %) was observed at low C/NO3-N (≤2), whereas at high C/NO3-N (≥2.25) led to ammonia formation. Ammonia production increased from 1 to 9 % with an increase in C/NO3-N from 2.25 to 6. Complete denitrification and no ammonia formation were observed at an optimum C/NO3-N of 2.0. Microbiological studies showed decrease in denitrifiers and increase in nitrite-oxidizing bacteria and ammonia-oxidizing bacteria at high C/NO3-N (≥2.25). Pilot scale studies were carried out with optimum C/NO3-N, and sustainability of the process was checked on the pilot scale for 5 months.

Performance and microbial diversity of an expanded granular sludge bed reactor for high sulfate and nitrate waste brine treatment

The disposal of waste brines has become a major challenge that hinders the wide application of ion-exchange resins in the water industry in recent decades. In this study, high sulfate removal efficiency (80%–90%) was achieved at the influent sulfate concentration of 3600 mg/L and 3% NaCl after 145 days in an expanded granular sludge bed (EGSB) reactor. Furthermore, the feasibility of treating synthetic waste brine containing high levels of sulfate and nitrate was investigated in a single EGSB reactor during an operation period of 261 days. The highest nitrate and sulfate loading rate reached 6.38 and 5.78 kg/(m3·day) at SO2−4-S/NO–3-N mass ratio of 4/3, and the corresponding removal efficiency was 99.97% and 82.26% at 3% NaCl, respectively. Meanwhile, 454-pyrosequencing technology was used to analyze the bacterial diversity of the sludge on the 240th day for stable operation of phase X. Results showed that a total of 9194 sequences were obtained, which could be affiliated to 14 phyla, including Proteobacteria, Firmicutes, Chlorobi, Bacteroidetes, Synergistetes and so on. Proteobacteria (77.66%) was the dominant microbial population, followed by Firmicutes (12.23%) and Chlorobi (2.71%).

Denitrification of synthetic concentrated nitrate wastes by aerobic granular sludge under anoxic conditions

The aim of the present work was to determine the denitrification potential of aerobic granular sludge for concentrated nitrate wastes. We cultivated mixed microbial granules in a sequencing batch reactor operated at a superficial air velocity of 0.8 cm s −1. The denitrification experiments were performed under anoxic conditions using serum bottles containing synthetic media with 225–2250 mg L −1 NO 3–N. Time required for complete denitrification varied with the initial nitrate concentration and acetate to nitrate–N mass ratio. Complete denitrification of 2250 mg L −1 NO 3–N under anoxic conditions was accomplished in 120 h. Nitrite accumulation was not significant (<5 mg N L −1) at initial NO 3–N concentrations below 677 mg L −1. However, denitrification of higher concentrations of nitrate (⩾900 mg N L −1) resulted in buildup of nitrite. Nevertheless, nitrite buildups observed in present study were relatively lower compared to that reported in previous studies using flocculent activated sludge. The experimental results suggest that acetate-fed aerobic granular sludge can be quickly adapted to treat high strength nitrate waste and can thus be used as seed biomass for developing high-rate bioreactors for efficient treatment of concentrated nitrate-bearing wastes.

Biological denitrification of high-nitrate wastewater in a modified anoxic/oxic-membrane bioreactor (A/O-MBR)

A modified anoxic/oxic-membrane bioreactor has been applied to the denitrification of a high strength nitrate waste (about 3600 mg/L nitrate-N) generated from an initiating explosive factory. Nitrate removal efficiency and nitrite accumulation in the treated water were investigated under various conditions set by several factors including the type of carbon source used, ratios of carbon to nitrogen, pH and hydraulic retention times (HRTs). The results of the preliminary experiments, which were carried out in parallel CSTR systems, demonstrated that sodium acetate had shown the best performance as the external carbon source. The optimal reaction parameters in the anoxic/oxic-membrane bioreactor were pH 7.5–8.5, C/N 1.56 and HRT 30 h, with over 99.9% of nitrate removed and without accumulation of nitrite. Explicitly high average-specific denitrification rate of 324 mg NO 3 −-N/g VSS/h could be attained under these conditions. The aerobic process and membrane module used subsequently could remove the residual COD, excessive biomass and soluble microbial products generated during the denitrification process.

Long‐term stability of biological denitrification process for high strength nitrate removal from wastewater of uranium industry

AbstractThe aim of the present study was to biologically denitrify uranium nitrate raffinate (UNR) from nuclear industry, which is a principle source of high strength nitrate waste. To denitrify the high nitrate waste, a pilot‐scale continuous stirred tank reactor was designed with two inbuilt settlers. Acclimatization of mixed culture with synthetic waste was carried out prior to the inoculation of the acclimatized sludge into the reactor. Initial concentration of nitrate in uranium raffinate was 77,000 mg/L NO3. It was diluted and used as a feed to the reactor. Concentration of nitrate in feed was increased gradually from 10,000 mg/L NO3 to 40,000 mg/L NO3 with hydraulic retention time (HRT) maintained at 34.4 h. Complete denitrification of 40,000 mg/L NO3 was achieved in a specified HRT.To facilitate understanding of the treatablity and long‐term stability of biological denitrification of UNR, study was carried out for 211 days by periodical perturbation of the system. Furthermore, to find the volume ratio of reactor to settler required for the full‐scale design of the denitrification plant, settling of acclimatized sludge was carried out. © 2008 American Institute of Chemical Engineers Environ Prog, 2008