WATER AND WASTEWATER
Year:2007 | Volume:18 | Issue:3 (63)|Papers Count:13

Metals discharged into coastal areas of marine environments are likely to be scavenged by particles and removed to the sediments. The sediments, therefore, become large repositories of toxic heavy metals. This research examined the concentrations of heavy metals (Al, Cd, Cu, Pb, Ni, Zn) in the near shore sediments in the alongshore direction of the Iranian coast of the Caspian Sea. Fourteen samples were collected and granulometric compositions were determined. The consideration of three grain size fractions (0.355 mm, 0.212 mm and 0.075 mm), plus fourteen bulk samples required analyzing 56 samples for the presence of heavy metals. Laboratory analysis of the samples was accomplished using the Cold Acetic Protocol, followed by Inductively Coupled Plasma Optical Emission Spectroscopy. Preparation of the samples involved the utilization of the Cold Acetic Acid Extraction Protocol established by the Great Lakes Institute for Environmental Research (GLIER), Canada. The results provided evidence of large differences in total metal concentrations in the sediment samples from the fourteen sites. Box and Whisker plots demonstrated that metal concentrations were not homogeneously distributed, and that there were large spatial variations in the median concentrations of heavy metals at each sample site. The statistical technique of discriminate analysis revealed that the six heavy metals had distinct and statistically significant concentrations at various locations along the coast. Concentrations reflected metal loadings from anthropogenic sources located at and in the vicinity of the sampling sites.

The efficiency of a pilot dissolved air flotation (DAF) unit is evaluated. It is the objective of the present study to determine the removal efficiency of DAF in removing turbidity and organic matter from the Karoon River feeding a water treatment plant. Water quality investigations over the study period revealed that, thanks to the self-purification process in the river, the Karoon water quality is acceptable with respect to total organic carbon (TOC) (never exceeding 2.89 mg/l) but its turbidity has great fluctuations (from as low as 42 to 1,000 NTU) due to the nature of the river. Its true color is in desirable conditions. Suspended solids removal efficiency of the pilot DAF unit varied from 38% to 95%, with an average level of 72%. The results from this study indicate that DAF removal efficiency is inversely related to the volume of inflow of solids into the system so that increasing TSS decreases removal efficiency. The high turbidity level in the absence of a primary sedimentation unit causes the flotation system to lose its desired efficiency. FAD cannot be, therefore, recommended for water treatment plants fed by the Karoon water unless a pretreatment unit is used. Furthermore, as FAD's TOC removal efficiency varies by up to 82%, and since part of the organic content includes volatile organic matter causing odors and undesirable taste, FAD is recommended as a complementary process in the treatment of high quality water.

Studies of turbidity removal in the past led to the development of coagulation and filtration processes. New processes are, nowadays, under development for improving upon impurity removal from water. In the present study, a DAF pilot plant and the jar test were used to investigate the optimum conditions for Turbidity, COD, HPC, and MPN removal. The goal of this study was to evaluate continuous inflow DAF performance on a pilot scale in improving the quality of spent filter backwash water in Isfahan Water Treatment Plant (WTP). The results showed that the continuous flow DAF using PACl as coagulant for removal of a turbidity level above 1000 NTU recorded efficiency levels of 97%, 72%, 75%, and 99% for COD, HPC, and MPN, respectively.Statistical analyses indicated that increasing saturation recycle rate led to improved removal of impurity and that the optimum saturation pressure was 4-5 atm for a recycle rate of 20-25 percent. It is concluded that the continuous flow DAF can be an efficient method for turbidity, COD, and bacterial removal from filter backwash water in Isfahan WTP. The turbidity and bacterial removal efficiencies in the coagulation method with sedimentation were reported to be up to 70 and 65 percent, while in this study, using DAF with PACI as coagulant, turbidity, COD, and bacterial removal efficiencies were as high as 97, 72 and 72 percent, respectively.A DAF system is, therefore, recommended for Isfahan WTP filter backwash water recovery and the designs and operation of this system should be a first concern for Isfahan WTP authorities.

Sonochemical degradation which combines destruction of the target compounds by tree radical reaction and thermal cleavage is a recent advanced oxidation process (AOP) with the potential to be effective for removing low concentrations of organic pollutants from aqueous streams. AOP s typically involve the generation and use of the hydroxyl tree radical as a strong oxidant to destroy compounds. The decomposition rate of pollutants by ultrasound depends on various factors. In this study, the effects of pH, initial concentration, hydrogen peroxide addition, and TSS concentration on the decomposition of organics in the secondary effluent have been investigated. COD analysis was taken as the index for organic concentration and two ultrasonic frequencies of 35 kHz and 130 kHz were used for treatment of wastewater samples. Results indicated that increases in organic concentration within the range of 20-60 mg/L would decrease organic removal efficiency from wastewater (p<0.05). But this efficiency may be improved by increasing TSS and H2O2 concentration levels. However, the effect of H2O2 depends on its concentration such that no considerable increase was detected in organic removal efficiency with £ 5mg/L of this chemical. Higher organic removal efficiencies can be expected only when H2O2 is added at a concentration level of 20 mg/L (p<0.01).Changes in pH level had no detectable effect on organic removal and for either methods of treatment (the ultrasound or the combined ultrasound/ H2O2), the efficiency of organic treatment did not increased neither at an acidic pH (=3) nor at a basic pH (=11). This result clearly shows the independence of the treatment on pH. Finally, it is noteworthy that increased TSS level (30 mg/L) has a positive effect on ultrasound treatment so that a nearly 40 percent improvement was observed in organic removal efficiency in this experiment. It may be concluded that increased TSS and H2O2 both increase the effectiveness of the ultrasound whereas, organic removal efficiency may decrease in this method as a result of increased concentration levels of these pollutants. Furthermore, pH variation was found to have no considerable effect on the treatment process.

This study was conducted to determine the qualitative parameters of the wastewater from the Olefin Unit of Bandar-e-Imam Petrochemical Complex in an attempt to identify the problems and to develop solutions. All the oily wastes generated in the unit under study are directed to the CPI and DAF systems where they are deoiled, diverted into the Eastern Pond, and, finally, discharged into the sea after a primary treatment process. In this study, information was collected on the process and on the effluent contaminant spreading sources in order to determine the sampling spots. Sampling was performed over 6 months and the effluent quality parameters (pH, TDS, BOD, COD, Oil, SO4=, PO4º, and NO-) were measured. Changes in the parameters were recorded on monthly, weekly, and daily bases. Combined samples were additionally used to ensure measurement accuracy. The results showed that the concentration levels of the parameters BOD, COD, oil, and phosphate ion in the effluent from the CPI system were beyond the national standards. Pollution load estimations for the relevant parameters also confirmed these results. Investigations revealed that COD and oil removal efficiencies in the CPI system were 17% and 10%, respectively, which cannot be desirable (paired sample Hest).Another problem observed was the effluent from the caustic wash tower. This effluent, which contains considerable quantities of caustic, polymer, yellow oil, and water, is discharged into the waste neutralization pond to leave the complex without further neutralization.

Increasing water demand with the peculiar climatic conditions in Iran has caused water scarcity and the subsequent social and political tensions. Efficient practices are, therefore, required for the allocation and optimal use of water resources. Water pricing and adoption of suitable tariffs may serve as instruments for demand management to achieve the required water management practices. Along these lines, the current tariffs used by the municipal drinking water sector and the consumption patterns of consumers in Neyshabour were studied over six two-month periods per year during 1380- 1383. Results show that average per capita consumption is 135 lit/day, which increases as we move from the first to the third period, and then decreases toward the sixth period. Moreover, the highest percentage of connections had a consumption level of about 5 to 22.5 m3/month while a very low percentage had a consumption level of over 65 m3/months. Examination of current tariffs against water consumption patterns revealed that current tariffs are too low to be capable of controlling consumption. In addition to high losses to water & sewage companies, an inevitable outcome of the current tariffs seems to be encouragement of more water consumption, none of which is compatible with water pricing policies and objectives.

Assessment of monitoring networks of surface waters and determination of main and tributary stations is an important step in the development and improvement of these networks and in increasing their efficiency. In this study, Principal Components Analysis, PCA, and Factor Analysis, PFA, techniques were employed to evaluate water quality monitoring stations on the Karoon River. From among the monitoring stations available, eight were selected and the measured data from 2002 to 2004 were used to determine the main and tributary stations. Finally, results were validated employing the regression analysis technique. Based on the results obtained in this study, only one monitoring station (Bandemizan) was identified as the main one among the eight stations selected. Also a similar study was conducted to determine main and tributary quality variables; however, the results of the KMO factor did not confirm using PFA and PCA for this part of study.

There are many natural and human subsystems in a watershed with their special interrelationships. These interrelationships must be duly considered for the integrated and comprehensive management of the water resources in a water basin. One example of such interrelationships includes upstream water development and utilization projects which adversely affect downstream water quality and quantity.Within the framework of an integrated water resources management, various water resources development and operation policies must be analyzed to select the most convenient one securing the benefits of all the stakeholders in the watershed. In this study, various operation policies in the Urmiah Lake Basin and the Aji Chai River Basin on the east of the lake are analyzed to determine their impacts on the water level in the lake. For this purpose, the Aji Chai Basin is subdivided into three sub-basins and the System Dynamics, which is a feedback-based object-oriented simulation approach, is used to develop the dynamic model of the region. To investigate the present scenarios, the ARMA (1, 1) model is used to generate 10 different time series for each sub-basin and the lake water level is accordingly determined for each case.

The lake in the protected Bakhtegan zone is the shelter to wildlife and very important from an ecological and environmental viewpoint. The lake has a unique diversity in terms of Halophilic and Halotolerant bacteria. Based on our experiments, from among the six genera ofHalobacteriaceae, only the four Halobacterium, Haloarcula, Halococcus, and Haloferax genera were isolated, the greatest frequency (mean: 54%) belonging to Halobacterium and the least frequency (mean: 4%) belonging to Haloferax among the isolated genera. The Halotolerant bacteria isolated included Pseudomonas sp., Flavobacterium sp., Micrococcus sp. and Bacillus sp. genera. The greatest number of Halotolerant bacteria isolated from the lake water was Pseudomonas (mean: 72%). Furthermore, the number of total coliforms was greater than the number of fecal coliforms. Statistical analysis revealed that Halophilic and Halotolerant colonies had the same mean numbers only at Tashk and Gomban sampling sites but that the mean numbers obtained at Dehzir sampling site was significantly different from those obtained at the former two. It was also found that increasing salt concentration and pH level increased the number of halophilic colonies while increased levels of dissolved oxygen decreased their numbers.Salt concentration, pH level, and DO level had similar effects on the number of total and fecal coliform colonies.

Stabilization pond is a sewage treatment method. Being rich in organic matter, sewage is a favorable habitat for a variety of aquatic insects. Given the importance of these insects in the organic transformation cycle, this stabilization was carried out in 2005 in order to identify the aquatic insects living in the stabilization ponds of Kashan University of Medical Sciences. For the purposes of this descriptive study, 9 series of sampling were performed and 1032 of larva, nymphs, and adults were collected from the four corners of each pond and sent to the laboratory for identification. The samples were identified using stereo-microscope and morphological identification keys. The species identified included Diptera (52%), Hempitera (24%), Ciclopodidade (12%), Hydroacarina (9.5%), Coleptera (0.77%), Aranida (0.67%), Hymenoptera (0.58%), and Odonata (0.48%). The families identified in the samples from the stabilization ponds under study involved Chironomidae and Culicidae from the Diptera order; Corixidae, Notonectidae, Cupepodae, and Copepodidae from the order Hemiptera; Hydrophilidae from the order Coleptera; Aranidae from the order Aranida; Vospidae from the order Hymenoptera; and Ashnidae the order Odonata.