An automatic method for the determination of ammonia in sea water

A method is described for the determination of ammonia in sea and estuarine water employing an autoanalyzer. The manifold design allows for the determination of ammonia concentration in the range of 0.2–20 μg at NH₄-N/l over a salinity range of 35-10‰ with negligible interference from amino acids.     

Nutrient discharges to Biscayne Bay, Florida: trends, loads, and a pollutant index

Changes in land use, management practices, and environmental conditions may all lead to detectable differences in nutrients transported to aquatic systems. Biscayne Bay, an oligotrophic estuary in southeastern Florida, requires minimal phosphorus and nitrogen inputs and here we quantified the effects of continued watershed development. Nutrient (nitrate/nitrite-nitrogen [NO_X-N], total ammonia nitrogen [NH₃-N], and total phosphorus [TP]) water quality data (1992-2006) from six monitoring sites were evaluated using trend analysis, load estimation, and a new Pollutant Empower Density (PED) index. The PED index assesses the effect of discharged pollutants relative to the background productivity of aquatic environments. NO_X-N, NH₃-N, and TP concentrations declined or exhibited no change at most sites, with only six instances of significantly (p < 0.1) increasing trends. Load estimates revealed higher NO_X-N loads in the southern, agricultural section of the watershed and higher NH₃-N and TP loads in the urbanized northern and central areas. NO_X-N loads from site MW04 (south) were the highest for all sites while site LR06 (north) had the highest NH₃-N and TP loads. Of the evaluated canal discharges, PED index values also suggested that canal discharges from these two sites (MW04 and LR06) had the greatest potential for impact in the bay. Overall, water quality is generally improving but canal discharges are coupled with land use activities in adjacent drainage areas. Trend analysis, load estimation, and the PED index can be used together to provide a more holistic interpretation of water quality, which is necessary for optimizing resources to meet watershed management goals.     

A simple and rapid method for the determination of lead and cadmium in sediment by graphite furnace atomic absorption spectrometry

A simple and rapid method has been proposed for the routine determination of Pb and Cd in sediment by graphite furnace atomic absorption spectrometry. 0.5 g of dry sediment is digested for 1 h at 140 C with a mixture of 10 ml of HF, 4 ml of HNO₃ and 1 ml of HClO₄ in the Teflon-lined bomb. Pb and Cd in this solution are measured by graphite furnace atomic absorption spectrometry, using an automatic sampling device. Several major elements such as Na and K in the solution give severe interferences in the determination of Pb and Cd, but these interferences can be successfully overcome by the addition of 1% (NH₄)₃PO₄ solution in the same volume of the sample solution for Pb and of 1%, (NH₄)₂SO₄ for Cd as the matrix modifiers to the sample solution respectively. Average contents of Pb and Cd in 36 sediments from 13 reservoirs in remote areas of Japan are 35 and 0.40 ppm, respectively.     

An automated procedure for the determination of total Kjeldahl nitrogen

A procedure for the determination of total Kjeldahl nitrogen in surface fresh waters and organic wastes is described. Organic nitrogen compounds are converted to ammonium sulphate by a catalytic (red mercuric oxide) acid-sulphate digestion. The digest time is 3 h and allows for a maximum of 36 samples, 2 blanks and 2 standards to be processed simultaneously. There is no pH adjustment required following the digestion. Calibration curves covering the ranges (i) 0.5–100 μg NH₃---Nl⁻¹ and (ii) 10–1000 μg NH₃---Nl⁻¹ were linear within ±2%. The detection limit of the method is 0.5 μg TKNl⁻¹. The concentration range of TKN for which the method is suitable is 0.5 μg Nl⁻¹–40 mg Nl⁻¹. The method displayed a high tolerance to interferences from copper, iron, mercury and hardness. Digest procedure gave a high recovery and reproductibility over a wide range of nitrogen compounds tested.     

Nitrogen pollution and source identification in the Haicheng River basin in Northeast China

A survey was conducted in the Haicheng River near Liaodong Bay to analyze the characteristics and sources of the in-stream nitrogen pollution throughout the year 2010. The results indicated that the total nitrogen (TN) concentrations in the river water all exceeded the GB3838-2002 standard for Class V guideline of 2.0 mg/l at all sampling sites during the sampling seasons. Ammoniacal nitrogen (NH₃-N) dominated TN during the spring season, while nitrate nitrogen (NO₃-N) dominated during the summer and autumn seasons. Different forms of nitrogen had significant seasonal variations (p < 0.01 or p < 0.05). Only NH₃-N and NO₃-N displayed distinct spatial differences at p < 0.05 and p < 0.001, respectively. Most forms of nitrogen were interrelated with physicochemical parameters during different seasons, displaying nitrification and denitrification processes that occurred in the river rather than seasonal biological demand. Based on the nitrogen parameters, the 30 sampling sites were divided into three clusters, by which the pollution sources from chemical nitrogen fertilizers, animal wastes, domestic sewage, and industrial wastewater were identified. Generally, the Haicheng River basin provided about 700 tons of the annual TN flux, contributing to the eutrophication of the Liaodong Bay and Bohai Sea.     

Characterization of bottom sediments in lakes using hydroacoustic methods and comparison with laboratory measurements

The acoustical properties of bottom sediments in two lakes were shown to be strongly correlated with clay content, organic C and total N concentrations, and other important sediment properties. The fractal dimension of the bottom echo was more strongly correlated with sediment physical and chemical properties than energy-based measures. The fractal dimension was also related to rates of PO₄-P and NH₄-N release from intact sediment cores and sediment oxygen demand. Measurements made at 430-kHz were more sensitive to differences in sediment properties than 201- or 38-kHz. Hydroacoustic measurements allow rapid assessment of properties important in lake restoration and water resource management.     

Inter-relationships between nitrogen balance, pH and dissolved oxygen in an oxidation ditch treating farm animal waste

The pathways of N in aerobic farm waste treatment systems are discussed in relation to the dissolved oxygen (DO) and pH of the mixed liquor. The change in pH, DO, oxygen uptake rate and nitrogen balance were monitored under steady, and non-steady, state conditions in an oxidation ditch treating undiluted pig waste. A kinetic analysis of the mass balance for nitrogen allowed an interpretation of the fate of nitrogen under different prevailing conditions. Undesirable accumulations of nitrite were noted in the presence of high levels of free NH₃ and HNO₂. The process was self-promoting and was encouraged by the influx of raw waste. Concentrations of 500 mg 1⁻¹ NO₂-N and 1200 mg 1⁻¹ NO₃-N were the maximum values observed and were considered to be the concentrations at which product inhibition arrested nitrifying activity. Attainment of these levels prevented complete nitrification despite an adequate retention time. pH and DO were inversely related probably through nitrification, but pH appeared to be lowered by accumulation of nitrite and nitrate anions, and thus by the balance between nitrification and denitrification. Considerable N loss through denitrification was found to occur despite apparently aerobic mixed liquors. At low DO simultaneous nitrification-denitrification could eliminate 90 per cent of the soluble-N. NH₃ desorption in laboratory cultures was found to be first order in free NH₃ but was not a significant mode of N loss under field conditions.     

Long term partial nitritation of anaerobically treated black water and the emission of nitrous oxide

Black water (toilet water) contains half the load of organic material and the major fraction of the nutrients nitrogen and phosphorus in a household and is 25 times more concentrated, when collected with a vacuum toilet, than the total wastewater stream from a Dutch household. This research focuses on the partial nitritation of anaerobically treated black water to produce an effluent suitable to feed to the anammox process. Successful partial nitritation was achieved at 34 °C and 25 °C and for a long period (almost 400 days in the second period at 25 °C) without strict process control a stable effluent at a ratio of 1.3 NO₂-N/NH₄-N was produced which is suitable to feed to the anammox process. Nitrite oxidizers were successfully outcompeted due to inhibition by free ammonia and nitrous acid and due to fluctuating conditions in SRT (1.0-17 days) and pH (from 6.3 to 7.7) in the reactor. Microbial analysis of the sludge confirmed the presence of mainly ammonium oxidizers. The emission of nitrous oxide (N₂O) is of growing concern and it corresponded to 0.6-2.6% (average 1.9%) of the total nitrogen load.     

Adsorption of ammonium to activated sludge

The adsorption of ammonium (NH₄⁺) to the sludge floc matrix has been investigated in two activated sludge treatment plants. When activated sludge was extracted in 1 N KCl the extractable amounts were between 0.5 and 1.3 mg NH₄⁺-N/l higher than the dissolved ammonium concentration at dissolved ammonium concentrations between 1 and 6 mg NH₄⁺-N/l. The difference between the extractable and the dissolved ammonium, the exchangeable ammonium, thus represented 18–30% of the dissolved ammonium concentration. A part of this, around 0.5–0.6 mg NH₄⁺-N/l was not exchangeable under the actual operational conditions in the treatment plants due to a slow desorption kinetics, but seemed to be accessible for nitrification under prolonged aeration. The highest observed amount of adsorbed ammonium corresponded to 0.4–0.5 mg NH₄⁺-N/gSS. Adsorption of ammonium should be investigated in more details and included in models for nitrogen mass balances for activated sludge.     

Electrochemical determination of pollutants in sea water: Toxic substances and nutrients

Coastal marine waters have a wide variety of important human uses and therefore must be protected against contamination. The main sources of their pollution (by toxic substances and nutrients) are the discharge of municipal sewage and runoff from agricultural areas. Excessive nutrient enrichment in the form of inorganic nitrogen (NH₄⁺, NO₂^?, NO₃^?) may be directly estimated by the use of ion selective electrodes (ISE), whereas the inorganic phosphorus can only be estimated indirectly. The total content of N, P and heavy metals may be estimated after decomposition of organic substances, using the ISE method in the case of P and N determination and the differential pulse anodic stripping voltammetry (DPASV) method for determining the heavy metals.     

Treating landfill leachate using passive aeration trickling filters; effects of leachate characteristics and temperature on rates and process dynamics

Biological ammoniacal-nitrogen (NH₄⁺-N) and organic carbon (TOC) treatment was investigated in replicated mesoscale attached microbial film trickling filters, treating strong and weak strength landfill leachates in batch mode at temperatures of 3, 10, 15 and 30 °C. Comparing leachates, rates of NH₄⁺-N reduction (0.126-0.159 g m^− 2 d^− 1) were predominantly unaffected by leachate characteristics; there were significant differences in TOC rates (0.072-0.194 g m^− 2 d^− 1) but no trend relating to leachate strength. Rates of total oxidised nitrogen (TON) accumulation (0.012-0.144 g m^− 2 d^− 1) were slower for strong leachates. Comparing temperatures, treatment rates varied between 0.029-0.319 g NH₄⁺-N m^− 2 d^− 1 and 0.033-0.251 g C m^− 2 d^− 1 generally increasing with rising temperatures; rates at 3 °C were 9 and 13% of those at 30 °C for NH₄⁺-N and TOC respectively. For the weak leachates (NH₄⁺-N < 140 mg l^− 1) complete oxidation of NH₄⁺-N was achieved. For the strong leachates (NH₄⁺-N 883-1150 mg l^− 1) a biphasic treatment response resulted in NH₄⁺-N removal efficiencies of between 68 and 88% and for one leachate no direct transformation of NH₄⁺-N to TON in bulk leachate. The temporal decoupling of NH₄⁺-N oxidation and TON accumulation in this leachate could not be fully explained by denitrification, volatilisation or anammox, suggesting temporary storage of N within the treatment system. This study demonstrates that passive aeration trickling filters can treat well-buffered high NH₄⁺-N strength landfill leachates under a range of temperatures and that leachate strength has no effect on initial NH₄⁺-N treatment rates. Whether this approach is a practicable option depends on a range of site specific factors.     

Nitrogen inputs to stream water from forests along an elevational gradient in New Mexico

Studies of nitrogen inputs in precipitation and outputs in stream water for a number of terrestrial ecosystems support the hypothesis that undisturbed communities have the ability to reduce losses of nitrogen via stream water. In spite of different levels of biomass, productivity and stream discharge for these communities, net losses of nitrogen were similar. Maintaining nitrogen in an organic or cation form (NH₃, NH₄⁺) is an important factor in minimizing loss. This may be accomplished by slow rates of mineralization, rapid plant uptake, and denitrification through the electron sink pathway. Denitrification by the dissimilatory pathway may also be important.     

Element dynamics of oak ecosystems on acid-sulphurous mine soils in the Lusatian lignite mining district (Eastern Germany)

Seepage water chemistry and input–output budgets of major ions are investigated within an oak chronosequence (Quercus petraea Liebl., 3 years; Quercus rubra L., 26 and 37 years) on acid-sulphurous soils of lignite mining. Due to declining intensity of weathering and deep percolation, the leaching rates of Fe, Al, Mn, Mg, Ca, NH₄ and SO₄-S from soil decline drastically within 34 years. Moreover, an enrichment of NH₄-N, NO₃-N, PO₄-P and K can be noticed, resulting from the accumulation of living biomass.     

Observations of nitrogen and phosphorus biogeochemistry in a surface flow constructed wetland

Free surface water constructed wetlands (CWs) provide a buffer between domestic wastewater treatment plants and natural waterways. Understanding the biogeochemical processes in CWs is crucial to improve their performance. In this study we measured a range of water and sediment parameters, and biogeochemical processes, in an effort to describe the processing of nutrients within two wetland cells in series. As a whole the studied CW effectively absorbed both nitrogen (N) and phosphorus (P) emanating from the waste treatment plant. However the two individual cells showed marked differences related to the availability of oxygen within the water column and the sediments. In one cell we speculated that the prevalence of surface plant species reduced its ability to function as a net nutrient sink. Here we observed a build-up of sediment organic matter, sediment anoxia, a decoupling of nitrification-denitrification, and a flux of N and P out of the sediments to the overlying water. The availability of DO in the surface sediments of the second studied cell led to improved coupling between nitrification-denitrification and a net uptake of both NH₄⁺ and PO₄³⁻. We hypothesise that the dominance of deeply rooted macrophytes in the second cell was responsible for the improved sediment quality.     

Chemical oxygen demand of some nitrogenous heterocyclic compounds

Chemical oxygen demands of fourteen nitrogenous compounds were determined by the dichromate method. Only pyridine and its derivatives were resistant to oxidation. Heterocyclic compounds containing one atom of nitrogen in a molecule, e.g. quinoline, pyrrole, proline, and indole were 90–100 per cent oxidized. Nitrogen is split off these compounds as NH₃. Heterocyclic compounds containing two or more atoms of nitrogen in a molecule are also easily oxidized. However, only a part of the nitrogen is split off as NH₃. On the basis of the results obtained it is possible to make the following generalization: nitrogen in amino groups is split off mostly as NH₃; quinoline, pyrrole, pyrrolidine, and indole nitrogen is split off as NH₃; from imidazole and pyrimidine rings, one atom of nitrogen is split off as NH₃ and one as N₂; from the purine configuration, two atoms of nitrogen are split off as NH₃ and two atoms as N₂; from isoalloxazine, three atoms of nitrogen are split off as NH₃ and one as N₂.     

Factors affecting nutrient loads in some Iowa streams

The export and concentration of inorganic nitrogen and total phosphorus from 34 watersheds in a northwestern Iowa lake district were measured during March 1971–August 1973. Annual nutrient losses were approximately 0.35 kg ha⁻¹ P. 6.7 kg ha⁻¹ NO₃-N, and 1.0 kg ha⁻¹ NH₃-N. A statistical analysis of the relationship between land-use and plant nutrients was used to determine differences among streams. Animal units in feedlots were significantly correlated with phosphorus and ammonia nitrogen (mg l⁻¹ and kg ha⁻¹ yr⁻¹). Nitrate nitrogen was negatively correlated with the percentage of watershed in marshland. Tile drainage and surface runoff from grasslands, feedlots, cornfields, and soybean fields were analyzed for nitrogen and phosphorus in spring 1974: mean values are given.     

A voltammetric electronic tongue as tool for water quality monitoring in wastewater treatment plants

The use of a voltammetric electronic tongue as tool for the prediction of concentration levels of certain water quality parameters from influent and effluent wastewater from a Submerged Anaerobic Membrane Bioreactor pilot plant applied to domestic wastewater treatment is proposed here. The electronic tongue consists of a set of noble (Au, Pt, Rh, Ir, and Ag) and non-noble (Ni, Co and Cu) electrodes that were housed inside a stainless steel cylinder which was used as the body of the electronic tongue system. As a previous step an electrochemical study of the response of the ions sulphate, orthophosphate, acetate, bicarbonate and ammonium was carried out in water using the electrodes contained in the electronic tongue. The second part of the work was devoted to the application of the electronic tongue to the characterization of the influent and effluent waters from the wastewater treatment plant. Partial Least Squares analysis was used to obtain a correlation between the data from the tongue and the pollution parameters measured in the laboratory such as soluble chemical oxygen demand (CODs), soluble biological oxygen demand (BODs), ammonia (NH₄-N), orthophosphate (PO₄-P), Sulphate (SO₄-S), acetic acid (HAC) and alkalinity (Alk). A total of 28 and 11 samples were used in the training and the validation steps, respectively, for both influent and effluent water samples. The electronic tongue showed relatively good predictive power for the determination of BOD, COD, NH₄-N, PO₄-P, SO₄-S, and Alk.     

Recovery of nitrogen and phosphorus from alkaline fermentation liquid of waste activated sludge and application of the fermentation liquid to promote biological municipal wastewater treatment

In previous publications we reported that by controlling the pH at 10.0 the accumulation of short-chain fatty acids (SCFA) during waste activated sludge (WAS) fermentation was remarkably improved [Yuan, H., Chen, Y., Zhang, H., Jiang, S., Zhou, Q., Gu, G., 2006. Improved bioproduction of short-chain fatty acids (SCFAs) from excess sludge under alkaline conditions. Environ. Sci. Technol. 40, 2025-2029], but significant ammonium nitrogen (NH₄-N) and soluble ortho-phosphorus (SOP) were released [Chen, Y., Jiang, S., Yuan, H., Zhou, Q., Gu, G., 2007. Hydrolysis and acidification of waste activated sludge at different pHs. Water Res. 41, 683-689]. This paper investigated the simultaneous recovery of NH₄-N and SOP from WAS alkaline fermentation liquid and the application of the fermentation liquid as an additional carbon source for municipal wastewater biological nitrogen and phosphorus removal. The central composite design (CCD) of the response surface methodology (RSM) was employed to optimize and model the simultaneous NH₄-N and SOP recovery from WAS alkaline fermentation liquid. Under the optimum conditions, the predicted and experimental recovery efficiency was respectively 73.4 and 75.7% with NH₄-N, and 82.0 and 83.2% with SOP, which suggested that the developed models described the experiments well. After NH₄-N and SOP recovery, the alkaline fermentation liquid was added to municipal wastewater, and the influence of volume ratio of fermentation liquid to municipal wastewater (FL/MW) on biological nitrogen and phosphorus removal was investigated. The addition of fermentation liquid didn't significantly affect nitrification. Both SOP and total nitrogen (TN) removal were increased with fermentation liquid, but there was no significant increase at FL/MW greater than 1/35. Compared to the blank test, the removal efficiency of SOP and TN at FL/MW = 1/35 was improved from 44.0 to 92.9%, and 63.3 to 83.2%, respectively. The enhancement of phosphorus and nitrogen removal was mainly attributed to the increase of influent SCFA, or rather, the increase of intracellular polyhydroxyalkanoates (PHA) which served as the carbon and energy sources for denitrification and phosphorus uptake. The addition of alkaline fermentation liquid to municipal wastewater, however, increased the effluent COD, which was caused mainly by the increase of influent humic acid, not protein or carbohydrate.     

The question of nitrification in the Passaic River, New Jersey: Analysis of historical data and experimental investigation

Historical NH₄⁺ and NO₃⁻ data from six stations on the Passaic River, New Jersey, were analyzed. The data for five of the stations span 1963 to 1976, and for the sixth station 1947 to 1976. Some of the conclusions reached are as follows:

1. (1) The concentration of NH₄⁺ fluctuated widely, but the trend was towards an increase with time.

2. (2) The concentration of NH₄⁺ was elevated during a period of extreme drought (1963 to 1966).

3. (3) The concentration of NO₃⁻ tended to increase smoothly with time.

4. (4) The concentration of NH₄⁺ increases longitudinally (with downstream travel).

5. (5) The loads (concentration × stream-flow) of both nitrogen species tended to increase with time.

6. (6) Substantial NO₃⁻ enters the stream from non-point sources.

7. (7) The potential for instream nitrification is not fully realized, as represented by elevated levels of NH₄⁺.

Item (7) was puzzling because conditions in the Passaic, especially in the summer, appear to be favorable for nitrification. The point was clarified, in part through an experimental investigation.River water samples, with and without added NH₄Cl, were incubated, and the course of the first step of nitrification was followed through the appearance of NO₂⁻. (The second step of nitrification was inactive during the experimental period.) The added NH₄Cl enhanced nitrification in samples from the uppermost stations (native NH₄⁺-N approximately 0.1 mg l⁻¹, but had little or no effect in samples from the middle and lower reaches (native NH₄⁺-N > 0.5 mg l⁻¹). Consequently, it was inferred that over most of the river's mainstem the growth of NH₄⁺-oxidizing bacteria was not substrate limited. There was also no indication of other nutrient limitations or of the presence of any inhibitors. This led to a projection of a 60-fold increase in the population density of planktonic NH₄⁺-oxidizers over a certain stretch of the river. However, no increase in the most-probable-number (MPN) of NH₄⁺-oxidizing bacteria was observed, which is consistent with item (7). In fact, at the end of a quiescent segment of the river the MPN's were anomalously low. This is attributed to the removal of cells from the water column through settling. This reasoning is extended to suggest that, throughout the river, settling may be the mechanism preventing a response of planktonic nitrifiers to the enrichment with NH₄⁺ from pollution sources. In turn, this could prevent a full expression of the potential for nitrification.The analyses are discussed from a regulatory perspective. It is concluded that the nitrification component of the Passaic's self-purification capacity is overburdened, and first became so in 1953.     

臭氧湿式氧化氨氮的降解过程研究

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