Effect of water treatment process on organochlorine pesticide residue levels in Ahvaz water treatment plant 2

1 Central Lab. of Isfahan Water & Wastewater Company; tel/fax: +983116693405 2 Dept. of Pharmacology&Toxicology, Pharmacy School, Ahvaz Jundishapour University of Medical Sciences, fax:+986113361544 3 Dept. of Food Science & Medical Hydrology, Pharmacy School, Ahvaz Jundishapour University of Medical Sciences 4 Central Lab. of Ahvaz Water & Wastewater Company 5* (Corresponding Author) Zenderood Environmental Research Center, Isfahan, Iran. E-mail: ordibehesht.m7@gmail.com Submitted: 26.10.2017. Accepted: 09.12.2017


Introduction
Over the past fifty years, pesticides have been an integral part of the world of agriculture.In the United States alone, production of pesticides reaches hundreds of millions in kilograms.Extensive use of pesticides in the areas of agriculture and public health in developing countries has resulted in environmental pollution.Studies of the creatures in the wild have clearly revealed that these pesticides have caused extensive contamination of the fish and bird species.With an abundance of healthy fruit and vegetables made available at low prices, no one entertains the doubts about the performance of pesticides in order to protect agricultural products.However, there is no such thing as "safe pesticide".Due to the non-alarming nature of such pesticides as the carcinogenicity potential of delayed poisoning of the nerves and fertility, experts and political leaders have shifted focus on pesticides to be the biggest concern of World Health Organization.Out of all the pesticides, chlorinated pesticides receive the most attention due to their lipophyllic nature, low biological decomposition, capability of biological concentration and introduction into the food chain.The key route of man's contact with these pesticides is water and food.Nowadays, WHO and FAO's main target is to pay attention to the traces of these poisons in water, food, and environment, especifically, the risks due to long-term contact even with small amounts of poisons and consequently their chronic poisoning.Of the total 1795.34Million cubic meters of located polluting wastewater produced and dumped yearly into the Karoun River, 1452.62 million cubic meters (81% of the total) is dumped into the upstream water hole of the treatment plants in Ahvaz.Of this quantity, 1412.75 million cubic meters (79% of the total) produced yearly is agricultural waste.Due to the heavy quantity of agricultural wastewater dumped into the Karoun River and the research findings indicating the poisons in the river, the study of the performance of treatment processes in reducing chlorinated organic poisons has become the target of this research.

Material and Methods
All glassware used in this analysis were carefully washed with soapy water, rinsed with distilled water ethanol, acetone and pesticide grade n-hexane respectively.All the solvents used (n-hexane, petroleum ether.diethyl ether, acetone) were pesticide residue analysis grade purchased from Merck Com.The Organochlorine pesticides standards were obtained from Dr. Ehrenstorfer GmbH (Augsburg, Germany) and the working solutions were prepared in hexane at 1 μg ml −1 .The sorbent material used, which was activated after drying at 150 C for 12 h before use, was Florisil 60-100 mesh obtained from Sigma-Aldrich.Collection sample In order to investigate the statue of qualification and quantification of the contamination in three point (entering waters into (AWTP)No.2-afterclarification & treated water) by selected organochlorine pesticides [(α, β, γ, δ )HCH, heptachlor, alderin, dielderin, (op', pp') DDT, (α, β) endosulfan and metoxychlor], 15 to 20 litter grab water samples were collected monthly at different hours during the day.After combining the 15-20 samples and preparing a mix, sample "in situ" water was acidified by sulfuric acid to pH 2 to eliminate biological activity in water.Then, 2.5 litters were filled into an amber bottle and then transported to laboratory for subsequent extraction and analysis.Liquid-liquid extraction 250 ml of water was extracted three times with 20ml n-hexane.The extract was combined and concentrated using a rotary vacuum evaporator to 10 ml.

Purification:
Extracts were purified by passing them through a glass column (20 cm, 0.8 mm id) packed with Florisil (10 cm) and Na2SO4 (2 cm), which was then eluted with ether: hexane solution: 200 ml at 6:94 v/v, followed by 15:85 v/v and 50:50 v/v.Thereafter, elutes were evaporated to dryness using a rotary vacuum and the residues were dissolved in 10ml hexane for gas chromatography analysis.The spiked matrix samples were analyzed as part of QA/QC.For this purpose adequate amount of the analysts of interest were spiked into the sample.Also, another aliquot of the samples was analyzed without spiking.Apparatus Analyses were done using an Agilent 6890N (HP) with a micro-cell electron capture detector (µ-ECD).A DB-5 column 30 mm ×0.25mm i.d containing 5% phenyl-methylpolysiloxane with a phase thickness of 0.25μm was used.The temperature program used for the analysis was: 210C to 275 C (13min) at 4C min −1 .The injector and detector were set to 300°C and 320°C in the split less mode.Nitrogen was used as the carrier at 0.7 ml min −1 and the make-up gas at 35 ml min − 1. Identification of peaks was based on the comparison of the retention times of compounds in the standard solutions.Quantification of the analyzed compounds was performed using the internal standard method.The concentration of pesticide residues in water ranged from 84% to 98% compared to the mean concentration of chlorinated organic poisons throughout the treatment process.

Results and Discussion
Comparison of the mean concentration for 12 chlorinated organic pesticides under this study has been drawn using ANOVA for T-Independent sample test and the results obtained have been included in Graphs 1-4 and Table 1.

Conclusion
The results of the study indicate traces of chlorinated organic poisons in the raw water of Treatment Plant # 02, Ahvaz and their considerable decrease throughout the process (Graphs 1-3).Table 01 indicates that reduction changes throughout the treatment process and also with the type of poison.During α-HCH coagulation and settlement, γ -HCH filtration and, on balance, throughout the entire treatment process, α-HCH, γ -HCH, Aldrin and Endosulfan indicated the greatest rate of reduction.A correlation coefficient of 97.75 % for reduction of organic materials (KMNO4 value) and reduction of poisons (Graph # 04) indicate the significance of the test for determining the value of organic materials based on the KMNO4 value in the study of the performance of the treatment process in the reduction of organic contaminants.The most significant result that can be derived from the 50 % reduction in the total poison concentration (Table # 01) is the importance of the common treatment processes (coagulation, settlement and filtration) in reducing the chemical contaminants.Hence, by optimization of such processes as coagulation, settlement and filtration, it is possible to not only reduce physical contaminants (turbidity), but also to improve the chemical desirability of water.With respect to the difficulties, that using such modern technologies as ozonation and reverse osmosis create in developing countries increased efficiency in the common treatment processes can pose as a higher priority.Researchers propose that in the future we study the efficiency of such techniques as Enhanced Coagulation in the reduction of contaminants.

Fig. 1 .
Fig. 1.Average concentration of 12 organochlorine pesticides in raw water samples of Ahvaz water treatment plant 2

Fig. 2 .
Fig. 2. Average concentration of 12 organochlorine pesticides in clarified water samples of Ahvaz water treatment plant 2

Fig. 4 .
Fig. 4. Correlation between variation in concentration of poisons and total organic matter (KMnO4 value).

Table . 1
. Average concentration and reduction percentage of organochlorine pesticides in different stage of treatment process.