Influence of nitrate and COD on phosphorus, nitrogen and dinitrotoluene (DNT) removals under batch anaerobic and anoxic conditions

In this study, the effects of COD to NO(3)-N ratio in the feed on PO(4)-P removal was investigated. Maximum PO(4)-P uptake was obtained in the anoxic reactor when the COD to NO(3)-N ratios were between 2 and 3.75. With the influent COD of 800-1500 mg COD/L a total of the maximum removable PO(4)-P was 56 mg PO(4)-P/L through 20 days of anaerobic/anoxic incubation, indicating 98% P removal in the anoxic reactor. Similarly, for the COD to NO(3)-N ratios varying between 2 and 3.75 maximum denitrification was observed. Through anoxic operation the poly-P bacteria are capable of removing NO(3)-N using VFA, COD as carbon source and NO(3)-N as the electron acceptor after methanogenesis has been completed. High NO(3)-N concentrations stopped significantly the P uptake. A total of 97-99% dinitrotoluene removal efficiencies in the reactors containing COD to NO(3)-N ratio of 2 and 3.75 after 20 days of incubation period. For maximum NO(3)-N and PO(4)-P removals optimal COD to NO(3)-N ratios, COD and NO(3)-N concentrations were 2-3.75, 2000-4000 mg COD/L and, 800-1500 mg NO(3)-N/L, respectively.     

Effects of ammonia and phosphate limitation on the activated sludge treatment of calcium-containing chemical waste

Laboratory-scale biotreaters were used to study the effects of NH(3)-N and PO(4)-P nutrients on the activated sludge treatment of a chemical waste containing soluble calcium (1300 mg/L). Units receiving high or low levels of NH(3)-N and PO(4)-P were similar in their ability to remove organic compounds from the waste. Adaptation of sludges to low PO(4)-P levels (<0.1 mg/L effluent) resulted in a marked accumulation of CaCO(3) in the biosolids, whereas those receiving high PO(4)-P (2-4 mg/L effluent) had little CaCO(3). Microscopic observations of CaCO(3) containing sludges showed substantial amounts of CaCO(3) crystals imbedded in the biomass. These flocs also appeared to be enriched with nonfilamentous bacterial species in contrast to flocs devoid of CaCO(3) which had a floc structure of filamentous and nonfilamentous organisms. Scanning electron micrographs of flocs grown under low NH(3)-N showed a microbial fibrillar network of exocellular material interconnecting cells in the floc matrix. The sludges adapted to low NH(3)-N also produced higher amounts of extractable polysaccharide. CaCO(3) containing biosolids were more dense, larger, and settled better (low SVI, high ISV) than flocs devoid of the precipitates. It is not known from our experiments whether PO(4)-P or some inorganic or organic polymer produced by the floc bacteria are involved in inhibiting CaCO(3) precipitation in the activated sludge treatment of calcium-containing wastes.     

Uptake rates of nitrogen and phosphorus in the water by Eichhornia crassipes and Salvinia auriculata

The main goal of this research was to survey information about the physiology of Eichhornia crassipes and Salvinia auriculata and their capacity to remove nitrogen and phosphorus from the environment, after quantifying the concentrations of the nitrogen (NO3-N, NH4-N and total-N) and phosphorus (PO4-P and total-P) compounds in the water. The macrophytes were incubated in the laboratory in plastic vials of approximately 1.5 litters containing a previously prepared solution of NH4NO3, NH4Cl and KH2PO4. Eichhornia crassipes exhibited the highest rates of nutrient reduction and the concentrations of NO3-N, NH4-N and PO4-P in the water influenced the uptake rates of nitrogen and phosphorus of the E. crassipes and S. auriculata. This information can help to reach adequate management strategies for aquatic macrophytes in order to reduce the eutrophication process in Imboassica lagoon.     

Growth of Dalbergia sissoo in desert regions of western India using municipal effluent and the subsequent changes in soil and plant chemistry

Increasing demand for fodder and fuelwood and the scarcity of a good quality water in arid areas has resulted in a search for an alternative source of water for biomass production. An experiment utilizing municipal effluent in growing Dalbergia sissoo was conducted. Five treatments included T1, municipal effluent at 1 PET (Potential evapo-transpiration) (without plant); T2, municipal effluent at 1/2 PET; T3, municipal effluent at 1PET; T4, municipal effluent at 2 PET; and T5, canal water at 1 PET. Observations included plant height, collar diameter at one-month intervals and plant mineral composition, mineral uptake and changes in soil properties at 24 months of plant age. Application of municipal effluent produced better growth in D. sissoo seedlings. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were greater in seedlings irrigated with municipal effluent than those of the seedlings irrigated by the treatment T5, and positively related with the quantity of irrigation. The concentrations were greatest in foliage compared to the other parts of seedling, with the exception of Cu concentration. Application of municipal effluents resulted in a 2- to 3-fold increase in the concentrations of soil K, Cu, Fe, Mn and Zn, whereas NH4-N and PO4-P availability increased by 8.1- and 4.5-fold, respectively. The increase in soil organic carbon was only observed in treatments T3 and T4. The accumulations of soil NO3-N, Na, Cu, Fe, Mn and Zn were more in lower soil layers but the other soil parameters showed their greatest values in the upper soil layer. Irrigation using municipal effluent did not result in toxicity to the seedlings before the age of 24 months. The results suggest that municipal effluent could be utilized, as an important source of water and nutrients in growing D. sissoo to increase biomass production in the needs of suburban dwellers. However, a preliminary treatment to reduce excess NH4-N and PO4-P will be required before application to the plantation.     

PS1沼泽红假单胞菌对集约化对虾养殖废水的净化作用

应用光合细菌PS1——沼泽红假单胞菌（Rhodopseudomonas palustris）净化集约化对虾养殖废水,探讨不同温度、不同菌浓度下PS1对养殖废水的净化效果。研究结果表明：PS1可有效降低对虾养殖废水中的COD、NH4^＋-N、NO3^-N、PO4^3--P,但对NO2^--N无降解效果,反而使之持续升高;PS1对养殖废水96h的降解率受温度和添加菌浓度的影响显著（P〈0．05）。当温度为26℃时,PS1对废水的降解活性较好;不同菌浓度组间的净化效果差异明显（P〈0．05）,综合净化效果,以12．5×10^5 CFU／ml的菌浓度为宜。     

Effect of carbon source on biological nutrient removal in a sequencing batch reactor

Sequencing batch operation was used for nutrient (COD, NH4-N, NO3-N, PO4-P) removal from synthetic wastewater by using different carbon sources. Operation consisted of anaerobic, anoxic, oxic, anoxic and oxic (An/Ax/Ox/Ax/Ox) phases with durations of 2/1/4.5/1.5/1.5 h. Glucose, acetate and a mixture of glucose/acetate were used as carbon source to yield a COD/N/P ratio of 100/5/1.5 in the feed. Sludge age was kept constant at 10 days. COD, NH4-N, NO3-N and PO4-P removal efficiencies were maximum at the levels of 96%, 87%, 81% and 90% respectively, when a mixture (50/50) of glucose and acetate was used.     

广东大中型供水水库的氮污染与富营养化分析

20 0 0年丰水期和枯水期对广东大中型水库的氮污染和富营养化现状进行了调查。结果表明 ,在调查的 2 0个大中型供水水库中 ,水质现状总体较好 ,70 %的水库处于中营养状态以下 ,30 %的水库开始出现富营养化现象。水库的总氮浓度普遍偏高 ,氮污染成为水库富营养化的重要原因。水库的总氮和DIN浓度存在地区性差异和季节性差异。枯水期水库的总氮及DIN浓度与叶绿素a的相关性极显著 ,而丰水期则无明显相关性。NO3 N是水体无机氮的主要组成部分 ,平均占DIN的 72 6 % ,而水库的NH3 N含量明显低于NO3 N ,平均占DIN的2 5 5 %。NO2 N的含量一般很低。水库的总氮、DIN和有机氮含量是判断水库营养状态的重要指标 ,而NO3 N和NH3 N在DIN中所占比例则是推测污染物来源的重要依据     

Transpiration, potassium uptake and flow in tobacco as affected by nitrogen forms and nutrient levels

BACKGROUND AND AIMS: Ammonium can result in toxicity symptoms in many plants when it is supplied as the sole source of N. In this work, influences of different nitrogen forms at two levels (2 and 15 mm N) on growth, water relations and uptake and flow of potassium were studied in plants of Nicotiana tabacum 'K 326'. METHODS: Xylem sap from different leaves was collected from 106-d-old tobacco plants cultured in quartz sand by application of pressure to the root system. Whole-shoot transpiration for each of the treatments was measured on a daily basis by weight determination. KEY RESULTS: Total replacement of NO(3)(-)N by NH(4)(+)-N caused a substantial decrease in dry weight gain, even when plants grew under nutrient deficiency. Increasing nutrient concentration resulted in a greater net dry weight gain when nitrogen was supplied as NO(3)(-) or NH(4)NO(3), but resulted in little change when nitrogen was supplied as NH(4)(+). NH(4)(+)-N as the sole N-source also caused reduction in transpiration rate, changes in plant WUE (which depended on the nutrient levels) and a decrease in potassium uptake. However, the amount of xylem-transported potassium in the plants fed with NH(4)(+) was not reduced: it was 457 % or 596 % of the potassium currently taken up at low or high nutrient level, respectively, indicating a massive export from leaves and cycling of potassium in the phloem. CONCLUSIONS: Ammonium reduces leaf stomatal conductance of tobacco plants. The flow and partitioning of potassium in tobacco plants can be changed, depending on the nitrogen forms and nutrient levels.     

Evidence for paralytic shellfish poisons in the freshwater cyanobacterium Lyngbya wollei (Farlow ex Gomont) comb. nov.

Lyngbya wollei (Farlow ex Gomont) comb. nov., a perennial mat-forming filamentous cyanobacterium prevalent in lakes and reservoirs of the southeastern United States, was found to produce a potent, acutely lethal neurotoxin when tested in the mouse bioassay. Signs of poisoning were similar to those of paralytic shellfish poisoning. As part of the Tennessee Valley Authority master plan for Guntersville Reservoir, the mat-forming filamentous cyanobacterium L. wollei, a species that had recently invaded from other areas of the southern United States, was studied to determine if it could produce any of the known cyanotoxins. Of the 91 field samples collected at 10 locations at Guntersville Reservoir, Ala., on the Tennessee River, over a 3-year period, 72.5% were toxic. The minimum 100% lethal doses of the toxic samples ranged from 150 to 1,500 mg kg of lyophilized L. wollei cells-1, with the majority of samples being toxic at 500 mg kg-1. Samples bioassayed for paralytic shellfish toxins by the Association of Official Analytical Chemists method exhibited saxitoxin equivalents ranging from 0 to 58 micrograms g (dry weight)-1. Characteristics of the neurotoxic compound(s), such as the lack of adsorption by C18 solid-phase extraction columns, the short retention times on C18 high-performance liquid chromatography (HPLC) columns, the interaction of the neurotoxins with saxiphilin (a soluble saxitoxin-binding protein), and external blockage of voltage-sensitive sodium channels, led to our discovery that this neurotoxin(s) is related to the saxitoxins, the compounds responsible for paralytic shellfish poisonings. The major saxitoxin compounds thus far identified by comparison of HPLC fluorescence retention times are decarbamoyl gonyautoxins 2 and 3. There was no evidence of paralytic shellfish poison C toxins being produced by L. wollei. Fifty field samples were placed in unialgal culture and grown under defined culture conditions. Toxicity and signs of poisoning for these laboratory-grown strains of L. wollei were similar to those of the field collection samples.     

微型生态系统中浮游动物正磷酸盐排泄率的估算

在考查罗非鱼或鲢、鳙下行影响的微型生态系统实验后期,对其唯一的浮游动物──大型的特定正磷酸盐(PO4-P)排泄率按不同大小级别和培育时间进行了测定,同时估算了该浮游动物种群的PO4-P排泄率。结果表明,大型的特定PO4-P排泄率依其体重的增长呈指数式下降,并且随着培育时间的增加而大大降低。有鱼系统中大型种群的PO4-P排泄率及其与浮游植物PO4-P摄取率的比值都显著地小于无鱼系统,而放养罗非鱼或鳙的系统之二项估算值又明显地比鲢单养系统低。看来,大型种群的磷排泄在鲢单养系统的PO4-P再生中起有一定的作用,而在放养罗非鱼或鳙的系统中所起的作用很小。       

An internal carbon source for improving biological nutrient removal

This study investigates the potential of mechanically disintegrated surplus activated sludge (SAS) to be used as an internal carbon source for biological nutrient removal (BNR) using two laboratory tests. In the phosphorus release test, the addition of disintegrated sludge as a carbon source was able to enhance phosphate (PO(4)-P) release by 14.9 mg l(-1) PO(4)-P when compared with acetate (7.9 mg l(-1) PO(4)-P), considering the 4.3 mg l(-1) PO(4)-P released in the control vessel, without carbon addition. Similarly, in the denitrification test, the nitrate (NO(3)-N) consumption rate was improved after the addition of disintegrated sludge (14.9 mg NO(3)-Ng(-1)VSS h(-1)) compared with acetate (7.0 mg NO(3)-Ng(-1)VSS h(-1)), taking in consideration the rate obtained in the control vessel (6.9 mg NO(3)-Ng(-1)VSS h(-1)). Two to five minutes of SAS disintegration time in the deflaker (2300-6200 kJ kg(-1) total solids) is recommended for this application.     

真江蓠(Gracilaria verrucosa)对网箱养殖海区的生态修复及生态养殖匹配模式

2006年8～9月,在浙江象山港花鲈(Lateolabrax japonicus)养殖网箱中吊养真江蓠(Gracilaria verrucosa)对网箱养殖造成的水体富营养化进行生态修复研究.通过45d内的平面监测、定点跟踪监测和断面监测,结果表明:该网箱养殖区水体呈严重富营养化状态,营养状态指数(E)为32.00,其营养盐分布由高浓度的中心区向周围150m非养殖水域扩散;真江蓠对养殖区的富营养化海水具有较好的修复效果:江蓠生态修复区及其相邻网箱中水体PO4-P、NO2-N、NH4-N和NO3-N含量显著低于非修复区(P＜0.01),修复区海水PO4-P、NO2-N、NH4-N和NO3-N浓度比非修复区分别降低22%～58%、24%～48%、22%～61%和24%～47%.养殖真江蓠45d后,修复区水体DO浓度和透明度显著高于非修复区(P＜0.05),DO平均提高28%,透明度平均提高30%;而修复区水体Chl-a浓度显著低于非修复区(P＜0.05),平均降低49%.通过建立基于N平衡的鱼藻生态养殖模式,每收获1kg花鲈至少需要匹配江蓠4.7 kg wet wt才可实现对鱼类排放N的完全吸收.因此网箱内栽培江蓠的混合生态养殖模式,可平衡因经济动物养殖所带来的额外营养负荷,有利于实现动物养殖环境的自我修复.     

Ammonia-nitrogen and orthophosphate removal by immobilized Scenedesmus sp. isolated from municipal wastewater for potential use in tertiary treatment

Scendesmus sp. isolated from municipal wastewater, entrapped in calcium alginate as algal sheets was employed to remove inorganic nutrients (N and P) from artificial and real domestic secondary effluents in parallel-plate bioreactor after starvation. The key factors affecting the removal efficiency (NH4+-N and PO4(3-)-P), system stability and reuse efficiency of screens were studied and discussed. It has been shown that cell density in the mixture of algal gel was the key factor compared with the thickness of the gel and the cell density of the reactor. A complete removal of NH4+-N and PO4(3-)-P was achieved within 4h of treatment in parallel bioreactors with the optimal cell density in the mixture of algal (2 x 10(8) algae mL(-1)) and 3mm gel sheets after second cycle. Nine cycles of wastewater treatment in 21 days were accomplished, holding higher removal efficiency. NH(4)(+)-N removal efficiency was 99.1% after 105 min, 100% after 135 min, PO4(3-)-P removal efficiency was 100% after 15 min in domestic secondary effluents. Immobilized Scendesmus sp. is shown to have great potentialities for removal of inorganic nitrogen and phosphorus from treated effluents.     

氮磷营养因子对赤潮异弯藻生长的影响

研究了N、P营养浓度对赤潮异弯藻(Heterosigma akashiwo)生长的影响.结果表明,该藻的生长速率与N、P营养因子浓度的关系符合Monod公式.在NO₃^--N浓度达到7.5 mg·L^-1时,赤潮异弯藻开始生长;浓度为3.75～75 mg·L^-1时,赤潮异弯藻的比生长速率与NO₃^--N浓度成正比关系.N营养充足时,赤潮异弯藻的最大生长速率μ_m-n=0.3475·d^-1,K_s-n=18.91 mg·L^-1.PO₄^--P浓度为0～1.0 mg·L^-1时,赤潮异弯藻的比生长速率与P浓度成正比关系;P营养充足时,赤潮异弯藻的最大生长速率μ_m-p=0.3024·d^-1,K_s-p=0.4086 mg·L^-1.N/P达到25后藻细胞浓度达到最大,表明N/P为25时最适合赤潮异弯藻生长.赤潮异弯藻最适合在N 37.5～225.0 mg·L^-1、P 5.0～50.0 mg·L^-1、N/P=25条件下生长.     

Growth and mineral accumulation in Eucalyptus camaldulensis seedlings irrigated with mixed industrial effluents

Effects of mixed industrial effluents on growth, dry matter accumulation and mineral nutrient in Eucalyptus camaldulensis seedlings were studied. The objective was to evaluate the adaptability of E. camaldulensis to effluent, tolerance to excess/deficiency of mineral elements and ultimately to determine suitable combinations of industrial/municipal effluent for their use in biomass production in dry areas. Different irrigation treatments were: T(1): good water; T(2): municipal effluent; T(3): textile effluent; T(4): steel effluent; T(5): textile effluent+municipal effluent in 1:1 ratio; T(6): steel effluent+municipal effluent in 1:2 ratio; T(7): steel+textile+municipal effluent in 1:2:2 ratio; and T(8): steel+textile effluent in 1:2 ratio. High concentrations of metal ions and low concentrations of Ca, Mg, K, Na, N and P in soil and seedlings of T(4) resulted in mortality of the seedlings within a few days. Addition of the textile/municipal effluent increased the survival time of the seedlings for two to three months in T(6), T(7) and T(8) treatments. Among the remaining treatments, the seedlings of T(2) attained 131 cm height, 1.97 cm collar diameter, 19 total branches and produced 158 g seedling(-1) of dry biomass at the age of 10 months. The seedling of T(3) produced the least growth and biomass. Growth equivalent to that of the seedlings of T(1) treatment was achieved when municipal effluent was mixed with textile effluent (T(5)). There was a decrease in soil pH, EC, SOC, NH(4)-N, NO(3)-N, PO(4)-P and basic cations and increase in the concentration of Cu, Fe, Mn and Zn with T(4) treatment. The reverse trend was observed in T(3) where a high concentration of Na might have reduced Mg and micronutrient concentration in seedlings potentially affecting root and leaf growth. Mixing of effluents may be useful in tree irrigation to increase biomass productivity, which is evidenced by improved growth in T(5) and survival in T(6), T(7) and T(8) treatments. Further, reduction of toxic concentration of metal ions in effluents may be helpful for a long-term field application.     

中国南极长城湾1994年1~2月间海水初级生产初析

 对中国南极长城湾内水体夏季的初级生产力于1994年1～2月间作了估计。发现其初级生产碳量约为0.7998·m-3·d-1。2月份高于1月份。表层、中层和下层相比,下层的日产量仍高。意味着该湾水体处于真光层范围内。水柱上下均有相应的初级生产。水温提高似有利于初级生产。初级生产的粗生产量与叶绿素a(Chl-a)、NH4-N、总N、ΣN/P的变化较为一致。营养盐相当充足。而与NO2-N、PO4-P 较不一致。与异养菌数也相悖。推测异养菌有较强的分解有机质能力和矿化作用活动。     

三峡大坝截流前后长江中上游江段水化学特性的初步调查

1997-1998年,在三峡大坝截流前后,对长江中上游地区十多个江段及若干个支流进行了多次的水质监测分析。结果表明:长江中上游水资源丰富,但污染较严重。从多项数据指标分析结果和多项资料表明,目前污染源主要为沿江工业和城市生活污水。长江干流污染远高于支流(嘉陵江除外).而大江截流对长江中上游的水质近期影响较小,可以忽略不计。       

Characterization of microalgae and associated bacteria collected from shellfish harvesting areas

Marine algal toxins are an important cause of seafood-associated outbreaks. Some marine bacteria living in association with algae are able to produce channel-blocking substances similar to PSP and TTX toxins and a role of these bacteria in the toxicity of dinoflagellates has been hypothesized. The aim of this study was to monitor, over a period of 2 years, areas used in shellfish production in the northern Adriatic Sea, through the determination of phytoplankton and the characterization of bacteria isolated from algae. Toxicity tests on bacterial extracts were performed using in vivo (mouse) and in vitro (cell culture) tests and by HPLC. The Dinophysis genus was detected throughout the year, while the Alexandrium genus was present in winter and spring. Sixteen bacteria isolated from algae, out of 61 bacterial strains tested by in vitro assay, were found to be producers of toxic substances that could block sodium channels in cells. HPLC analysis for the detection of PSP and TTX toxins always gave negative results, but their presence in concentrations undetectable by HPLC, and/or the production of chemically different substances with similar biological action, could not be excluded.     

长江口地区大气湿沉降中营养盐的初步研究

为了解大气湿沉降对于赤潮发生的影响,2000年5月至2001年4月在嵊泗群岛采集了64个雨水样品,并分析了其中的N、P、Si等营养盐的浓度．结果表明,营养盐月平均浓度之间相差较大,与风向即不同的污染物来源和降水量等因素有关;营养盐季节通量分布不均,季节性明显．除冬季外,其他3个季节均能成为赤潮的诱发因子;NO3--N、NH4+-N、NO2--N、PO4^3-P和SiO3^2-Si的年均浓度依次为20．23、30．14、0．1l、0．045和3．43μmol·L-1,年通量分别为2．67×10^8、3．98×10^9、0．014×10^8、0．0059×10^8和0．45×10^8mol,与河流输入量相比,湿沉降对营养盐的年输入量较小．     

Settleability and kinetics of a nitrifying sludge in a sequencing batch reactor

A physiological study of a nitrifying sludge was carried out in a sequencing batch reactor (SBR). Pseudo steady-state nitrification conditions were obtained with an ammonium removal efficiency of 99% +/- 1% and 98% +/- 2% conversion of NH4+-N to NO3 - -N. The rate of biomass production was negligible (1.3 +/- 0.1 mg microbial protein-N.L(-1).d(-1)). The sludge presented good settling properties with sludge volume index values lower than 20 mL.g(-1) and an exopolymeric protein/carbohydrate ratio of 0.53 +/- 0.34. Kinetic results indicated that the nitrifying behavior of the sludge changed with the number of cycles. After 22 cycles, a decrease in the specific rate of NO3- -N production coupled with an increase in the NO2- -N accumulation were observed. These results showed that the activity of the nitrite oxidizing bacteria decreased at a longer operation time. Ammonia oxidizing bacteria were found to exhibit the best stability. After 4 months of operation, the specific rates of NH4+-N consumption and NO3- -N production were 1.72 NH4+-N per microbial protein-N per hour (g.g(-1).h(-1)) and 0.54 NO3- -N per microbial protein-N per hour (g.g(-1).h(-1)), respectively.