Phytoplankton and zooplankton modeling of pishin reservoir by means of an advection-diffusion drought model

Phytoplankton and zooplankton concentrations in Pishin reservoir are predicted employing a three-dimensional numerical model in this paper. Modeling is performed using a numerical model based on mass transport equation. Advection, diffusion and source/sink processes are considered as separate subroutines for predicting the concentrations of phytoplankton and zooplankton in the reservoir. Finite volume method is used for solving the governing equations of water quality and water flow. The model is adopted for drought periods and dry climates. Water flow in the reservoir is simulated by Fluent software that is a finite volume numerical model. The model also uses a sub-model for compatibility providing of geometry between software and water quality model. A one-year period of experimental works and sampling is done in the study area. Phytoplankton and zooplankton cycles are used to determine the sources and sinks. Standard methods are chosen for experimentation. The concentrations of phytoplankton and zooplankton are calculated and measured in a one-year period. The concentrations of phytoplankton and zooplankton decrease in the depth of water and the decease rate is not linear. Also the concentrations are increase in the times after the maximum floods because of the inflows contain high amounts of nutrients. The calculated values by the model are in good agreement with measured values of laboratory works. It was concluded that the model can be used for water quality prediction in such aquatic environments

Determination of biokinetic coefficients for activated sludge processes on municipal wastewater

Biokinetic coefficients and efficiency for three activated sludge processes including conventional, extended aeration, and contact stabilization were determined in pilot-scale for six months in Isfahan south municipal wastewater treatment plant. These systems were operated under two different MLSS concentrations in aeration tank. For each MLSS, five periods were considered in base of flow rate and sludge retention time [SRT]. The samples from the influent wastewater, reactor and effluent were collected periodically and experimented by the Standard Methods. The data were analyzed by the Excel and SPSS softwares. The investigation showed that the yield coefficient [Y], decay coefficient [kd], maximum specific growth rate and saturation constant [Ks] for conventional activated sludge process were in the range of 0.48-0.8 mgVSS/mg sCOD, 0.0189-0.026 1/day, 0.95-0.98 1/day and 52-71 mg sCOD/L, extended aeration: 0.6174-1.2512 mgVSS/mg sCOD0.0198-0.0309,1/day 1.96-3.17, 1/day and 311.7-508 mg sCOD/L and for contact stabilization: 0.6322-0.713 mgVSS/mg sCOD1 0.0172-0.0387, /d0.23-1 0.42/d and13.8-50.8 mg sCOD/L, respectively. In the conventional and contact stabilization processes values of the coefficients were within the range of those reported in the literature. However, in the extended aeration process, values of Ks and Y in MLSS of 5000mg/L were out of ranges. The sensitivity analysis of changes in the biokinetic coefficients showed direct relationship of kd and Ks with the concentration of the effluent substrate. Whereas micro [max] is inversely related to concentration of the effluent substrate. In addition, regardless of the type of substrate and MLSS concentration, the effluent substrate concentration is more sensitive to micro [max] than kd and Ks. The results also showed a COD removal efficiency ranging for conventional process between 83 and 92.5%, for extended aeration process between 88 and 93.8%, and for contact stabilization process 77 and 92%. The effluent COD was simulated using the biokinetic coefficients determined during the study

Effects of sludge from wastewater treatment plants on heavy metals transport to soils and groundwater

Heavy metals accumulation in soils under the application of sewage sludge and effluent from wastewater treatment plants is a major environmental concern. Transport of heavy metals through the soils may eventually lead to the groundwater contamination and their accumulation in soils and crops. Silt loam soils covered by sludge and effluent of Tehran wastewater treatment plant were used in this study. The vertical and horizontal distributions of sludge-borne Cd, Cr, Zn, Pb, Fe, Cu and Ni were studied within four plots. Measured loadings of heavy metals to the plots from the sludge application were Fe, 284.75, Pb, 90.28, Zn, 109.5, Ni, 60.28, Cu, 27.76 Cr, 28.58 and Cd, 4.5 mg/kg. Two hundred and forty soil samples were taken from areas within the plots and up to 100 cm depth on each side of the plots. Leachate water from the plots which contaminates groundwater was collected and the concentrations of heavy metals were measured. The determined concentration of sludge-borne in leachate Cr, Ni, Zn, Fe, Pb, Cu and Cd were 0.803, 0.785, 0.532, 0.439, 0.110, 0.180 and 0.019 mg/l respectively. The results of this study can be used for the management of effluent and sewage application in agricultural lands and crop production. The groundwater quality can be monitored and improved as well

Prediction of daily suspended sediment load using wavelet and neuro-fuzzy combined model

This study investigated the prediction of suspended sediment load in a gauging station in the USA by neuro-fuzzy, conjunction of wavelet analysis and neuro-fuzzy as well as conventional sediment rating curve models. In the proposed wavelet analysis and neuro-fuzzy model, observed time series of river discharge and suspended sediment load were decomposed at different scales by wavelet analysis. Then, total effective time series of discharge and suspended sediment load were imposed as inputs to the neuro-fuzzy model for prediction of suspended sediment load in one day ahead. Results showed that the wavelet analysis and neuro-fuzzy model performance was better in prediction rather than the neuro-fuzzy and sediment rating curve models. The wavelet analysis and neuro-fuzzy model produced reasonable predictions for the extreme values. Furthermore, the cumulative suspended sediment load estimated by this technique was closer to the actual data than the other one. Also, the model could be employed to simulate hysteresis phenomenon, while sediment rating curve method is incapable in this event

Pesticide transport and transformation modeling in soil column and groundwater contamination prediction

Pesticide transport and transformation were modeled in soil column from the soil surface to groundwater zone. A one dimensional dynamic mathematical and computer model is formulated to simulate two types of pesticides namely 2,4-dichlorophenoxy acetic acid and 1,2-dibromo 3-chloro propane in soil column. This model predicts the behavior and persistence of these pesticides in soil column and groundwater. The model is based on mass balance equation, including convective transport, dispersive transport and chemical adsorption in the phases such as solid, liquid and gas. The mathematical solution is obtained by finite difference implicit method. The model was verified with experimental measurements and also with analytical solution. The simulation results are in good agreement with measured values. The major findings of this research are the development of the model which can calculate and predict the concentration of pesticides in soil profiles, as well as groundwater after 4, 12, 31 days of pesticide application under steady state and unsteady water flow condition. With the results of this study, the distribution of various types of pesticides in soil column to groundwater table can be predicted

Autism and celiac disease: failure to validate the hypothesis of a possible link

Autism is a heterogeneous condition and the possible pathogenic role of several different factors was postulated. Previous studies reported the existence of a linkage between autism and celiac disease [CD]. The aim of this study was to determine the association between autism and CD by anti-gliadin [AGA], anti-endomysial [AEA] and tissue transglutaminase [tTG] antibodies. Thirty four consecutive autistic children [18 boys and 16 girls] aging 9.2 +/- 4.1 years [range 4-16 years] and thirty four age- and sex- matched healthy anonymous blood donors [18 boys and 16 girls] aging 10.8 +/- 4.0 years [range 4-16 years] were included. None of the patients and controls had symptoms [or positive family history] suggestive of specific gastrointestinal diseases. AGA and AEA antibodies [lgG and IgA], and lgA-tTG were detected by ELISA. The individuals with positive serology were offered duodenal biopsies. lgG-AGA was found in 4 patients [11.8%] and 2 controls [5.9%], while IgA-AGA was found in none of the patients and controls. All patients presented normal values of lgG and lgA-AEA similar to the control group. There was no significant relationship between the levels of AGA and AEA antibodies and the severity of autism in the patient group. The levels of lgA-tTG in four patients [but no controls] were in the borderline range and two of them were found to have mild villous changes with chronic inflammatory cells. However, characteristic histological features of CD were absent. No evidence was found that children with autism were more likely to have celiac disease than children without autism

Conceptual hydrosalinity model for prediction of salt load from wastewater flows into soil and ground water

Dynamic hydrosalinity models are available, but are not used extensively on a large scale soil which receives wastewater from industrial areas, partly because adequate database are expensive to be obtained. Thus, for this reason, there is an urgent need to assess the salt and other pollutant loads collected in wastewater flows into the soil and/ or ground water systems. A conceptual hydrosalinity model was used on two major underlying principals of mass balance and steady state. This model was initially tested on the 4,117 km[2] plains west of the Yazd-Ardakan district in the central part of Iran. This model was used at a time when the soil and ground water salinity problem was serious due to the high shortage of water. It was possible to calibrate the model with +/- 2% of the flow volume and total dissolved solids of the industrial wastewater discharge from over 2,000 factories. The verification results were 98% of the measured values. Moreover, this model was tested for the verification of the model data from the analysis of 36 wells' water in the area where industrial wastewater discharge was used. The results showed that most of the indices of total dissolved solids, total suspended solids, biological oxygen demand and chemical oxygen demand are above standard levels. The results of the model can be used for the management practice of the reduction of salt pollutant load in the area to achieve sustainable development for location of industries in the study area

Optimization of motor vehicle industries wastewater treatment methods with the aim of heavy metals removal and water reuse in pilot scale

The waste of motor vehicle industries is mainly the result of washing, coloring and various stages of chassis manufacturing, which include oil, grease, dyestuff, chromium, phosphate and other pollutants. In the present research, extended aeration activated sludge biological treatment plant is being considered and evaluated, for the removal of heavy metals and pollution load from industrial wastes and sanitary wastewaters, and on the pilot scale for optimization of waste treatment method for motor vehicle industries. To accomplish the pilot experiments, the natural waste of Bahman motor vehicle factory is used. Effective factors on efficient removal of heavy metals and pollution load such as concentration of biological mass [MLVSS], COD, BOD, pH in the extended aeration activated sludge biological treatment system, in different ratios of the mixing of industrial waste to sanitary wastewater have been experimented and evaluated. The performance of the above system, in the best of conditions, removes about 90% of pollution load and 65% of heavy metals existing in the industrial wastes. After analyzing the experiments, it is concluded that the removal of heavy metals through biological methods is possible and moreover it is feasible to biologically treat the mixing of motor vehicle industries effluent and sanitary wastewater up to the ratio of one to one, if guided exactly and scientifically

Results and complications of endoscopic ultrasound guided-FNA in patients with pancreatic and gastrointestinal submucosal lesions

Linear endoscopic ultrasonography [EUS] is a proven modality for the diagnosis and treatment of different gastrointestinal lesions. The aim of this study was to describe the role of EUS-FNA in the evaluation of pancreatic and submucosal lesions. Over a 1-year period, in a prospective descriptive study, patients referred to Naft Hospital, underwent linear EUS. Of the 40 linear EUS performed, 32 [80%] patients had pancreatic lesions which 26 [81%] of these cases were referred for pancreatic tumor biopsy. The most of these tumors [73%] were in the head of pancreas. EUS-guided fine-needle aspiration biopsy was performed in all 26 patients successfully without complications, which in 16 [61.5%] of them the diagnosis of pancreatic malignancy confirmed cytopathologically. Sensitivity and specificity of this method in pancreatic lesions were 84% and 100%, respectively. Eight patients [20%] were referred because of submucosal upper gastrointestinal lesions which in 7 [87.5%] of them GIST were diagnosed. Sensitivity and specificity of EUSFNA in submucosal lesions was 100%. No adverse effect of EUS-FNA was observed. EUS-FNA is a safe method with an acceptable accuracy in the evaluation and diagnosis of pancreatic and submucosal lesions. The results of this study are similar to that reported previously from other countries. Performing this new method requires more gastroenterologists and pathologists experience as well as more support from different societies [such as gastroenterology and surgery]

Modeling contaminant transport in soil column and ground water pollution control

A mathematical and computer model for the transport and transformation of solute contaminants through a soil column from the surface to the groundwater is presented. The model simulates selenium species such as selenate, selenite, and selenomethionine as well as pesticides and nitrogen. This model is based on the mass balance equation including convective transport, dispersive transport, surface adsorption, oxidation and reduction, volatilization, chemical and biological transformation. The governing equations are solved numerically by the method of implicit finite difference. The simulation results are in good agreement with measured values. The major finding in the present study indicates that as the time of simulation increases, the concentration of different selenium species approaches the measured values