Protozoa of a rotating biological contactor treatment plant in Mexico

A protozoological analysis of the biofilm developed on the discs of an RBC unit was performed using light microscopy; the species found belonged to 2 phyla: Sarcomastigophora with 23, and Ciliophora with 30 species. All isolates were free-living with the exception of Tritrichomonas fecalis. Most abundant species were: Euglena gracilis, Paramecium multimicronucleatum, Tetrahymena pyriformis, Polytoma uvella, Didinium nasutum, Bodo caudatus, Vorticella microstoma, Cyclidium glaucoma, Sathrophilus agitatus, Antophysa vegetans, and Urothrica farcta. Ciliates predominated over the flagellates in number and diversity. According to their locomotion most abundant species were free-swimming, followed by the attached, and crawling forms. In relation to their nutrition most frequent species were bacterivorous, saprozoic, and carnivorous. Values of the saprobic index calculated for each sampling station indicated that α-mesosaprobic conditions prevailed along the contactor with a zone of overlap with polysaprobic conditions at station IV. The RBC received an influent flow that varied from 1.5 to 13.5 L s^?1 and a soluble BOD₅ which range from 46 to 170 mg L^?1. The contactor studied showed an overall BOD₅ removal of 86% and a COD removal of 74%. DO levels influenced the values obtained for the saprobic index and the kind of protozoan populations and communities present. The biological findings (indicator species of the saprobic system), clearly reflected and agreed with the physicochemical results obtained simultaneously; the results showed that the system performed efficiently.     

BOD,COD and TOC studies of petroleum base cutting fluids

The biological oxidation criteria of 21 oil-in-water metal working lubricants have been examined using classical Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) analyses. The O₂ required by unacclimated sewage microorganisms ranged from 14 000 to 297 000 mg O₂ l^?1 lubricant. Based on the initial COD and/or TOC, the extent of biological oxidation ranged from 1.6 to 35.0% over the five day test period.     

Utilization of created wetlands to upgrade small municipal wastewater treatment systems

Created wetlands offer a low cost, low maintenance, and practical alternative for upgrading secondary municipal wastewater treatment systems. The removal efficiencies, effects of seasonal temperature variations, and effects of increased loading rates on contaminant removal within such a system was studied by Auburn University researchers at a created wetland site in Hurtsboro, Alabama. The 0.16 ha system consisted of a two cell wetlands planted with cattails (Typha latifolia), bulrush (Scirpus validus), arrow duck potatoes (Sagitaria latifolis), burr reeds (Spargaminum eurycarpun), water pennywort (Hydrocotyl ranunculoides), and parrotfeather (Myriophyllum brasiliense). Testing occurred from January through September of 1988 at hydraulic loading rates of 169, 289, and 345 m³ ha^?1 d^?1. The monthly average total suspended solids influent: effluent mg L^?1 concentration ratio during the study period was 135:19 while the monthly average total BOD₅ influent: effluent mg L^?1 concentration ratio was 38:8. Once the system stabilized, the monthly average total BOD₅ effluent concentration remained essentially constant over the range of average BOD₅ loading rates employed in this study. Total Kjeldahl N removal was more effective at loading rates of 2.6 kg ha^?1 d^?1. The monthly average influent: effluent TKN mg L^?1 concentration ratio was 15:4.     

养殖水中总有机碳与化学需氧量和生化需氧量相关性的研究

总有机碳能较全面地反映水体有机物的污染程度,总有机碳的测定具有操作简单、分析快速、结果准确等特点。研究了养殖水中的总有机碳与化学需氧量和生化需氧量相关性,总有机碳与化学需氧量的相关系数为０.９９１８,总有机碳与生化需氧量的相关系数为０.９３６２,可以用总有机碳来估算和衡量水体的污染情况。     

Mobilization of heavy metals from river sediments of Northern Greece by complexing agents

The influence of NTA, EDTA, STPP, Triton X100, PO _inf4 ^sup3 and NO _inf3 ^sup? on the mobilization of Pb, Cd, Cu, Cr and Mn from sediments of two rivers located in Northern Greece was studied. The release caused by all examined complexing agents was higher in deionized water than either Axios or Aliakmon river water due to the lack of competition of Ca and Mg cations with the heavy metals for the studied complexing agents, and the decrease of ionic strength. From all examined agents NTA and EDTA showed the greater mobilization ability. Copper showed the greater tendency for remobilization by all examined agents, (according to the order: EDTA?NTA, Triton X1004 PO _inf4 ^sup3? > NO _inf3 ^sup3? ?STPP) while Cr and Mn the smallest following the orders: NTA, PO _inf4 ^sup3? >> NO _inf3 ^sup? , Triton X1004 EDTA, STPP and STPP > EDTA > NTA > Triton X 100 ? PO _inf4 ^sup3? NO₃, respectively. An increase in mobilization was noticed with an increase of agent concentration and time of shaking.     

Titanium oxide nanoparticle effects on composition of soil microbial communities and plant performance

We examined the effect of TiO₂ nanoparticles (NPs) on the growth of maize and soybean plants and associated soil microbial communities. Plants were grown in a greenhouse, and low levels of undoped or nitrogen-doped TiO₂ NPs were applied. Plant growth and nutrient content were determined, and effects of NPs on composition of soil microbial communities were examined using terminal restriction fragment length polymorphism analysis (TRFLP) of rDNA. We found no significant effects of TiO₂ NPs on plant growth, nutrient content, or the composition of bacterial communities within the rhizosphere. However, arbuscular mycorrhizal fungal communities were affected by application of undoped and nitrogen-doped TiO₂ NPs. This observation may be partially attributed to the small but significant TiO₂ NP uptake levels in the root tissues of both plants. Our results suggest that even low concentrations of TiO₂ NPs may influence some important groups of soil microbes, such as mycorrhizal fungi, but changes in the composition of microbial communities may not affect plant growth under conditions of adequate moisture and nutrients.     

The experimental phytotoxicology of germanium in relation to silicon

The common belief that the sensitivity of plants to Ge is evidence for a Si requirement has been examined experimentally using barely, wheat, cucumber and radish cultivars. All 4 test plants were inhibited by Na₂GeO₃ (metagermanate) at 1 mM or less, including germination, shoot height, root length, and first leaf growth in barley and wheat. The application of Na₂SiO₃ (metasilicate) counteracted Ge-inhibition only in barley. Further, only barley growth was stimulated by the application of Na₂SiO₃. Necrotic lesions were characteristic of Ge-toxicity only in barley leaves, and were reduced when Na₂SiO₃ was supplied.     

Pyro- and tripoly-phosphate contents of sediments

A method to determine pyrophosphate (PP) and tripolyphosphate (TPP) in sediments was developed. Sediment was extracted with 2% EDTA + 0.1 M NH₄F followed by a second extract of 2% EDTA + 1 N NaOH. Orthophosphate (OP), PP, and TPP were separated by anion exchange chromatography, the fractions collected, and P determined after extraction into isobutanol. The limit of detection of the method was 0.5 μg P g^?1 sediment. Fourteen sediments were tested and the highest TPP found was 1.8 μg P g^?1 sediment. Thirteen of the sediment samples contained less than 1 μg P g^?1 as TPP. Only three of the 14 samples contained more than 1 μg P g^?1 as PP. The highest level of PP (8.5 μg P g^?1) was found in sediment from an animal waste lagoon. Estimates of error and reproducibility were made from analysis of samples with added PP and TPP. The error for samples containing 36.9 μg P g^?1 as PP was ± 7.6, and for TPP at 12.3 μg P g^?1 the error was ± 3.3. The values for PP and TPP were underestimated by 6 and 36%, respectively.     

Simulation of flow patterns and ion-exchange in soil percolation experiments

An increased understanding of ion-exchange processes in raw-humus was obtained by simulations using quantitative mathematical models. The work is based on a series of percolation experiments with a water flow of about 1 mm min^?1 through raw-humus samples of 4 cm thickness. For the input solutions consisting of 10^?3 N H₂SO₄, HNO₃, HCl and NaCl the results indicate that cation-exchange reactions are the most important processes for the chemical composition of the run-off. Since a large part of the water flows quickly through the soil, both the water residence time and the ion-exchange kinetics must be taken into account. As a basis for the chemical model, a hydrologic sub-model reproducing the residence time distribution of the flow in the soil is used. Considering the ions H⁺, M⁺ (monovalent metal ions) and M²⁺ (divalent metal ions), four different chemical models were tried but only one of them gave satisfactory agreement with the experimental results. This model has 5 independent parameters and consists of first and second order chemical processes.     

Comparative evaluation of NTA and EDTA for extractive decontamination of Pb-polluted soils

Nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA) were compared for their ability to solubilize Pb from a highly-contaminated (PbT 21%) soil collected from a battery recycling facility. For chelant concentrations below 0.04 M (representing a 1:1 chelant-to-Pb_T molar ratio), EDTA released 10 to 30% more Pb than NTA. NTA-to-Pb T ratios greater than 1:1 reduced Pb recovery because of readsorption of Pb(NTA)₂ ^4? onto positively-charged oxide soil components at pH < 8.5. For the EDTA system, however, complexation completely bound all coordination sites of Pb and EDTA, leaving no functional groups available for surface adsorption. Thus, Pb recovery progressively increased with higher EDTA concentrations, although the additional Pb release with each EDTA increment became smaller. For pH < 5 and EDTA/Pb of 2:1, Pb recovery exceeded 90%. The addition of 0.5 M NaC1O₄ enhanced Pb recovery by EDTA for pH 5 to 12, but substantially suppressed recovery by NTA for pH < 11. Because Pb release by NTA was diminished by high ionic strength and chelant-to-metal ratios, NTA may be limited as a soil washing reagent. Stronger complexation and consistent Pb desorption behavior by EDTA favors its use.     

A mechanism for hydrochloric acid production in cloud

A theoretical model describing the general interaction between atmospheric trace gases, such as S0₂, NH₃, C0₂ and 0₂, chemical reactant gaseous product H₂SO₄ and hydrometeors containing NaCl is proposed to study a possible mechanism for HCl production in non-precipitating cloud and the determination of the pH value of cloud droplets. Four different cloud droplet distributions have been used to estimate the upper limit of the amount of gaseous HCl released into the atmosphere resulting from the evaporation of cloud droplets. It is shown that the acid production and the amount of HCl released depend on the following factors: (a) the temperature of the cloud; (b) the oxidation rates; (c) the ambient concentration of SO₂, NH₃, and H₂SO₄; (d) the life cycle of the cloud; and (e) the liquid content of the cloud. This proposed chemical model also predicts a pH value spectrum depending on the cloud droplet distribution. Field measurements for the dependence of pH value on particle size and spatial distribution of gaseous HCl are recommended.     

Response surface methodology to understand the anaerobic biodegradation of organochlorine pesticides (OCPs) in contaminated soil—significance of nitrate concentration and bioaccessibility

Purpose

Problems associated with Organochlorine pesticide (OCP)-contaminated soils have received wide attention. To understand the anaerobic biodegradation process constraints, innovative mathematical analysis methods are effective.

Materials and methods

Response surface methodology (RSM) and Tenax TA extraction method combined with the first-three-compartment model were employed to systematically investigate the role of nitrate concentration and bioaccessibility enhancer (methyl-β-cyclodextrin, MCD) in the anaerobic biodegradation of OCPs in contaminated soil.

Results and discussion

The sole addition of either KNO₃ or MCD could facilitate the anaerobic biodegradation of OCPs. The highest biodegradation for total OCPs, hexachlorocyclohexanes, endosulfans, and chlordanes were 71.6, 82.1, 68.3, and 55.6 %, respectively, when 20 mM KNO₃ and 3.0 % (w/w) MCD were applied simultaneously. As predicted by RSM, the theoretical maximum biodegradation for total OCPs ranged from 60 to 80 % when 20 to 25 mM KNO₃ and >2.5 % (w/w) MCD were applied simultaneously. Tenax TA extraction method demonstrated the enhancement of OCP bioaccessibility caused by MCD addition. Changes in the soil microbial activities also suggested the positive effects of adding suitable amounts of KNO₃ as a cosubstrate to facilitate the anaerobic biodegradation of OCPs.

Conclusions

The amount of KNO₃ and MCD are crucial in influencing OCP biodegradation. RSM was demonstrated to be a powerful tool to estimate and predicting the optimal OCP biodegradation under KNO₃ and MCD application simultaneously.     

Biochemical Oxygen Demand Relationships in Typical Agricultural Effluents

Understanding the variables controlling biochemical oxygen demand (BOD) of effluents from agricultural systems is essential for predicting and managing the water quality risks associated with agricultural production. In this study, short- and long-term oxygen demand behaviors of waters from primarily agricultural sources and their relationships with other parameters were evaluated. A total of 46 water samples were generated from diverse organic sources commonly associated with agricultural activities and analyzed for BOD and other various water quality parameters. Short-term BOD (BOD₂ and BOD₅) were significantly correlated with total organic carbon (TOC), particulate organic carbon (POC), and dissolved organic carbon (DOC) (R ²?=?0.62–0.77, p?<?0.001), likewise to total nitrogen, total Kjeldahl nitrogen, and nitrite–nitrogen (NO₂–N) (R ²?=?0.40–0.55, p?<?0.001). Long-term BOD (BOD₆₀) was generally poorly correlated with these C and N fractions. Phosphate (PO₄–P) exhibited a positive and linear relationship with both short- and long-term BOD, whereas chloride (Cl) tended to inhibit oxygen demand. Multivariate combinations of each of TOC, POC, and DOC with NO₂–N, and Cl or PO₄–P improved the predictions of both short- and long-term BOD. The ultimate BOD (BOD_u) derived from the first-order kinetics was highly correlated with BOD₆₀ (R ²?=?0.81, p?<?0.001) whereas BOD₆₀ was correlated with BOD₅ (R ²?=?0.60, p?<?0.001). Overall the results indicated that C and N forms along with PO₄–P and Cl were the dominant factors controlling the oxygen demand behaviors of agricultural effluents.     

Influence of wetlands and coal mining on stream water chemistry

Comparisons of stream water chemistry over a 2 yr period in East Fork, which drains an entirely forested watershed, and Big Run, which drains a forested watershed 8 % of which is occupied by Big Run Bog, indicated that Big Run Bog had no effect on stream water H⁺ or Cl^? concentrations, but with increasing stream discharge the wetland was a source of Ca⁺⁺ Mg⁺⁺, K⁺, Na⁺, NO₃ ^?, and SO₄ ^?, and a sink for Fe^{+ +}. Further comparisons with Tub Run, which drains a forested watershed, 13 and 12% of which is occupied by Tub Run Bog and an abandoned, unreclaimed coal surface mine, respectively, suggested that Tub Run Bog removes H⁺, Ca ++, Mg⁺⁺, Fe⁺⁺, and 50₄ ^? from inputs of acid mine drainage. Wetland areas on the landscape contribute to the regulation of stream water chemistry in ways that are different from upland areas, and wetlands may have considerable applied potential for minimizing the impact of the mine drainage on stream water quality.     

Mobility of chlorofluorocarbons in deposits of shredder wastes from plastic and metal utilizing industries

Chlorofluorocarbons (CFCs) are used as propellants in spray cans, as refrigerants and as blowing agents for plastic foams, which are finally dumped together with solid wastes in landfills. We found shredder waste from plastic and metal utilizing industry to be highly contaminated with F12 (CF₂Cl₂) and less with F11 (CFCl₃). By means of model calculations with one dimensional diffusion models, we were able to estimate the amount and rate of outgassing of CFCs. The models were validated with measured vertical gas concentration profiles. From our results we conclude that deposition of shredder wastes containing CFCs results in a quick loss of these substances to the atmosphere with halflifes of ～ 2 d. In order to reduce CFC emission from landfills, contaminated wastes should be covered with compacted adsorbing layers (e.g., sewage sludge) immediately after their deposition.     

Application of the ‘fast’-method to a long term interregional air pollution model

The Fourier Amplitude Sensitivity Test (FAST) is applied to an interregional Air Pollution Model which simulates SO₂/SO₄-concentrations and -depositions as an annual average. The results are discussed and problems connected with the application of the FAST-method are reported.     

Air quality impact of the nanticoke industrial development

This paper discusses the results of the air quality monitoring activities, especially for three of the Ontario Ministry of the Environment's criteria pollutants (SO₂, O₃, and total suspended particulates). In the early 1960's Nanticoke Hamlet, located on the northern shore of Lake Erie, was selected for a large industrial development program. The first phase saw the commissioning of a 4000 MW Ontario Hydrothermal generating station, a 100 000 bbl day^?1 Texaco refinery and a Stelco steel plant with an initial annual capacity of 1.7 × 10⁶ tonnes. Favorable climatological data was one of the criteria used for selecting this site. Extensive monitoring of ambient air and water quality was carried out prior to the construction phase of the program. Post operation monitoring has also been done on a continuous basis. The data collected to date indicate that the impact of the industrial activity on air quality in the Haldimand-Norfolk region has been very small, with less than 20 exceedances per year of the hourly air quality criterion for SO₂ (250 ppb) being observed across the network, and total suspended particulates being similar to other rural locations in Ontario. Only 03 has a substantial number of exceedances of the criterion (80 ppb hourly average) during the summer months, primarily due to long-range transport into the area from across Lake Erie.     

Structural Influence on Photooxidative Degradation of Halogenated Phenols

The influence of structure on degradation of five halogenated phenols (XPs) by UV/H₂O₂ process was investigated. The combined influence of type or number of substituents and UV/H₂O₂ process parameters (pH and [H₂O₂]) on the degradation kinetics of 2-fluorophenol (2-FP), 2-chlorophenol (2-CP), 2-bromophenol (2-BP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) was studied using modified miscellaneous 3³ full factorial design and response surface modeling (RSM). Studied XPs obey first-order degradation kinetics within the investigated range of process parameters. Determined degradation rate constants (k _obs) were correlated with process and structural parameters by the quadratic polynomial models. Analysis of variance (ANOVA) demonstrated RSM models’ accuracy and showed that, in addition to pH and [H₂O₂], model terms related with the pollutant structure are highly influential. k _obs of mono-XPs follow the decreasing order 2-FP, 2-CP, and 2-BP, while CPs follow the decreasing order 2-CP, 2,4-DCP, and 2,4,6-TCP. Biodegradability (biochemical oxygen demand (BOD)₅/chemical oxygen demand (COD)) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals. The observed differences are correlated with the structural characteristics of studied XPs.     

Application of henriksen's ‘acidification indicator’ and ‘predictor nomograph’ to two adirondack lakes

During the period 1977–1980 we studied the effects of highly acidic precipitation (mean pH 4.1 to 4.2) on the chemistry of three Adirondack lakes: Woods Lake, Panther Lake, and Sagamore Lake. Two of these lakes (Woods and Panther) are enough like those lakes of southern Sweden and Norway studied by Henriksen that they should constitute a valid test of his ‘acidification indicator’ and ‘predictor homograph’. In our comparison we used data from weekly samples taken near the surface of the lakes during unstratified summer and fall conditions over a 3 yr period. The acidification indicator and predictor nomograph were developed using data from lake samples taken under similar conditions in Scandinavia. Our principal finding is that with regard to the empirical line of the acidification indicator (that Henriksen found separated data from lakes receiving precipitation greater or less than pH 4.6) and with the precipitation pH axis of the predictor nomograph, these two methods of evaluation are not directly applicable ‘as is’ to our lakes. The reason for this is that the chemistry of precipitation in the Adirondacks is significantly different from (and for) which the acidification indicator and predictor nomograph were developed. In the Adirondacks, acids other than H₂SO₄ play a much greater role in the overall acidity of the precipitation. This causes relationships between precipitation pH and lake chemistry in the two regions to be different.     

The origin and deposition history of polycyclic aromatic hydrocarbons in the finger lakes region of New York

Studies aimed at determining the deposition history of energy related, potentially carcinogenic, polycyclic aromatic hydrocarbons (PAHs) deposited in the sediments of Cayuga Lake, in the Finger Lakes Region of central New York State, are described. PAH fluxes in the 1850's were at least an order of magnitude less than the maximum rates in the period of 1940 to 1955. PAH fluxes began to decline before the Milliken coal fired power plant, located on Cayuga Lake, started service in 1955. Correlation between the PAH flux into the sediments and fossil fuel usage and emissions for the states of New York, Ohio and Pennsylvania and the United States as a whole, suggests that modern, high efficiency fossil fuel fired power plants are minor sources of PAHs compared to coal related residential heating and industrial combustion. Similar comparisons with historic emissions data do not support the hypothesis that PAH flux is a useful indicator of the combustion sources which produce the `acidifying' compounds SO₂ and NO_x for the Finger Lakes region.