STUDY ON WATER QUALITY INDICATORS AT TAIA TREATMENT PLANT HUNDEDOARA COUNTY

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1 STUDY ON WATER QUALITY INDICATORS AT TAIA TREATMENT PLANT HUNDEDOARA COUNTY Ramona Violeta CAZALBAŞU, Camelia CĂPĂŢÎNĂ, Cîrţînă DANIELA "Constantin Brâncuşi" University of Tg-Jiu, Faculty of Engineering, 3, Gorj, Romania; Abstract: Water is consumed in its natural form or in a processed one. It is a well-known fact that enterprises, institutions, energy and agriculture consume it as processed water whereas the population consumes it as drinking water or wastewater. This paper presents the study of water quality indicators from the treatment plant Taia in Hunedoara County. The following quality indicators were determined: turbidity,, alkalinity, chlorine oxide and organic substances. The determined quality indicators revealed that they fall within the limits set by legislation, with some exceptions. In each step of purification of organic substances there has been a continual reduction, this being carried out both biologically because of the biomass deposited on sand grains in the filter bed as well as especially during the oxidation step with active chlorine. Keywords: water treatment, indicators, Hunedoara. 1. INTRODUCTION The complexity revealed in the water molecule, its participation in the multitude of vital processes, should draw a tremendous attention to rational use of the resources. On the contrary, in fact, it is still prevalentan erroneous idea that water sources are inexhaustible, therefore no difficulty is encountered in this respect. Water "is everywhere" in the seas and oceans, the rivers, the glaciers, ponds and underground layers. However water does nolonger seem unlimited. Present and future needs require cautious interpretation of global quantitative data. Only a small part of the total amount is directly usable and precisely this amount is seriously threatened by pollution. Among the three main forms of existence of the water - air, surface and underground, there is a close relation due to a certain order of succession of the known natural phenomena: evaporation, condensation, infiltration and leakage. Solar energy occurs significantly to achieve the water cycle; it is the determining factor in the formation of atmospheric vapor and even part of the soil. A number of calculations have shown that in the course of a year, the land area of 1 m 3 receives about one million kcal of solar energy, heat, able to vaporise the water layer thickness of 1.30 m 1. After evaporation, the wind ensures the circulation and distribution of water vapor in the atmosphere. Depending on the temperature and degree of saturation of the air, the water can condense into very fine particles (mist) or coarser particles, liquids and solids (clouds). In favorable conditions, the clouds give rise to precipitation falling on the earth's surface as rain, hail or snow. A part of the water precipitations falls in rivers, seas and oceans, where the cycle starts again by evaporation, whereas the other part of the condensed water arriving on dry surface follows different paths. 243

2 Thus, about one-fourth of it forms streams or torrents, or it flows through streams and rivers into seas and oceans. Approximately half of the water from precipitation, after reaching the heated land, evaporates. This happens particularly where there is no possibility of being transported into seas or oceans (Sahara). To this evaporated water it is added that derived from animal and plant transpiration. Fig. 1. Water cycle in nature and in different fields of application Another part of the rain water fallen on the dry land (about 25%), penetrates into the soil, raising the level of underground waters or increasing the flow of underground sources. Also, in addition to the soil water that can be incorporated in the soil by capillary action or evaporation, it may form small underground rivers too. It should be remembered that a very small fraction of water precipitations falls on the ground as snow that melts or forms glaciers. Besides those from infiltration, groundwater can be fossil water, preserved in the geological water-tight and juvenile layers synthesized in the depth of the earth's crust. Taking into account the water use in various industries, its circuit is completed as shown in Figure 1. This paper presents the study of water quality indicators from the treatment plant Taia in Hunedoara County. EXPERIMENTAL Turbidity was determined experimentally with MicroTPI portable turbidimeter. PH was determined with the experimentally determined pattern portail Hanna meter (4) The alkalinity of water was determined experimentally by titration with 0.1 N HCl, in the presence of phenolphthalein or methyl orange indicators. The determination of chloride was carried out using the argentometric method. The determination of oxidizable organic substances in the water was performed using the KMnO4. 244

3 NTU turbidity HCL alkalinity ml / L Chloride mg / L Means org mg O 2 / L Total was determined by complexing the metal cationsca 2+ and Mg 2+, which forms the with the disodium salt of ethylene diamine at 10 in the presence of Eriochrome Black T indicator. RESULTS AND DISCUSSIONS In order to characterize the water treatment plant operation Taia the data presented in tables.1 şi.2 represent the average data for five months of the year on various monitored quality indicators. Table 1. Water quality indicators in months: December- February and March to April Raw water settled water filtered water Water Mains CMA Total NTU turbidity HCL alkalinity ml / L Chloride mg / L Means org mg O 2 / L Table 2. The quality indicators for the raw, decanted, filtered and network water Raw water settled water filtered water Water Network CMA , Total ,5 9,5 6,5 9,5

4 From the data obtained it is seen that in the case of higher turbidity of 20 NTU over conditions given in the reactive coagulants (Al sulphate and lime for adjustment) treatment efficiency is of 62.38% in comparison with the case where no positive coagulants is administered, and the efficiency is only 16.14%, which is 3.86 higher because of the influence of coagulants in the process of sedimentation (2). The differences remain in the other steps of treatment, and the total efficiency of the entire apparatus in the first case is 92.46%, while in the second case only 60.70%. It should be noted that in both cases the treated network water falls under quality requirements regarding its turbidity. The turbidity of raw water triggers off the frequency in the washing of filters. As the alkalinity measured by titration with hydrochloric acid is concerned it is noted that the process using solid content does not change so that the overall efficiency is only 5%. Chloride content gradually increases from the water source into the network water, which is particularly difficult to explain since, up to the disinfection with chlorination stage, hardly any chlorine based chemical is used. In these circumstances we believe there are experimental errors andtherefore the treatment efficiency could not be calculated properly. Free residual chlorine must be found only in the network water, being an indicator of water quality certifying the oxidative destruction of microorganisms. As for the content of organic substances in the raw water after each treatment step, measured in mg O 2 / L the treatment efficiency was calculated as follows: For worst case treatment efficiency is calculated in three steps, namely: Q T treatment efficiency in the settling step I: 1 2 5,56 2,30 D ,63% 5,56 1 F Q T treatment efficiency in the filtration step II: 2 3 2,30 1, ,86% 2,30 2 CL Q T treatment efficiency in the chlorination step III 3 4 1,13 0, ,15% 1,13 3 Total efficiency: 1 TOTALE 1 4 5,56 0, ,55% 5,56 246

5 With respect to organic matter present in water there is a continuous decrease observed in each stage of treatment, the reduction being done both biologically due to the biomass on the sand grains deposited in the filter bed and in the oxidation step with active chlorine. Thus, the overall treatment efficiency for the organic substance content is 82.55%. The for the worst-case treatment efficiency is calculated in three steps, namely: - treatment efficiency in the settling step I: 1 2 7,8 7,5 D 100 3,84% 1 7,8 - the effectiveness of treatment in stage II filtering: 2 3 7,5 7,6 F ,33% 2 7,5 - the efficiency of the treatment in the chlorination step III: 3 4 7,6 7,1 CL ,57% 3 7,6 Total efficiency: 1 4 7,8 7,1 total ,97% 7,8 1 In the process used to treat water the is within the quality limits during the whole process oscillating around neutral value in the network water. CONCLUSIONS Free residual chlorine, which is an indicator of water quality showing the destruction of microorganisms by oxidation, must be found in the network water. There is a continuous drop in each stage of purification of organic substances, reduction being both biological carried out by the biomass on the sand grains deposited in the filter bed and especially during the oxidation step with active chlorine. The filtering operation is influenced by two categories of factors: characteristic factors of the influent and of the filtered. Double filters (by flow) occurred due to the need to improve current performance of rapid filters with up or down current. By combining the two-way filtering productivity is achieved at filtering stations. The improvementin water filterability at water treatment planttaia in Hunedoaracounty is achieved by replacing existing filters with fast filters. 247

6 BIBLIOGRAPHY 1. C. Teodosiu, Industrial and Drinking Water Technology Matrix Rom, Bucharest M.Negulescu, Treatment of Urban Wastewater, Ed Tehnica, Bucharest, V. Rojanschi,Th. Ognean The guide for wastewater treatment plant operator, EdTehnica, Bucharest Intraenvironment, Faculty of Chemical Industry, Environment Quality Control, Workings of practical laboratory, CarteaUniversitara, Antoniu R, Bondor D.,ConstantinescuGh, Ghederim V., Marcu M, Negulescu M, Popescu V,.- Industrial Wastewater Treatment, vol. 1, Ed. Tehnica, Bucharest, Water Law 107/ Official Gazette 244 / Cirtina Daniela 2005 Water Pollution, Ed Sitech. 8. NTPA 002. Quality indicators of wastewater discharged into the sewage network of cities 248