Water Quality Assessment of Karnaphuli River Showing the Seasonal Variations

Transcription

1 Paper ID: EE International Conference on Recent Innovation in Civil Engineering for Sustainable Development () Department of Civil Engineering DUET - Gazipur, Bangladesh Water Quality Assessment of Karnaphuli River Showing the Seasonal Variations Tasnuva Farnaz 1 & Abdullah Al Masud 2 Abstract The river Karnaphuli is one of the Himalayan Rivers which originated from the Lushai Hills in Mizoram. In the east region of Bangladesh (BD), it is considered to be the lifeline to business activities for both the Hill people and the plain land population. But the recent statistical scenario shows that massive amount of pollution due to disposal of untreated effluent from industries (directly or indirectly), oil spilling from the ships, sewage dumping etc. coupled with unabated encroachment has posed a serious threat to the very existence of the river Karnaphuli and survivals of its aquatic lives. As the river water is used for several purposes like drinking, domestic use, recreational purposes, fish cultivation, irrigation etc. it is very important to know about the existing water quality of Karnaphuli. Besides there is a variation of water quality parameter values for different seasonal periods. On that note, the study period has been divided into dry period (November-April) and wet period (May-August) to undergo various laboratory experiments on the water quality parameters like ph, Turbidity, Alkalinity, Dissolved oxygen( DO), Biological Oxygen Demand (BOD 5), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Total Dissolved Solid (TDS), Electrical Conductivity (EC) etc. of the Karnaphuli river water. After evaluating each and every experimental results it has become very clear that in most of the cases during the dry period of the year the concentrations of ph, Alkalinity, BOD 5, COD, CO 2, TDS, Salinity, EC etc. are higher than the BD Standards for drinking water, recreational use, Fish Culture, irrigation etc. Especially the d/s locations of the river which are close to the estuary and mostly concentrated with industries need full attention for the improvement of its condition. On the other hand the concentrations of turbidity and TSS are found above the allowable limit during the wet period of the year due to surface runoff. Keywords: Bangladesh Standards; Industrial waste & Sewage disposal; Seasonal Variations; Water quality parameters 1. Introduction Chittagong being the business capital of Bangladesh, it has always been very important to keep the Karnaphuli River healthy as it serves so many economical purposes for the whole nation. But in the era of urbanization and industrialization it is very pathetic to observe that all of our natural resources including the river water are degrading its quality day by day and posing more threats to our existence. The industrialization process itself involves the pollution cycle which is becoming worse with the speedy growth of population. The recent studies indicates that the river has already reached a dangerous state in terms of parameters like total solid in the water, level of alkalinity, salinity and turbidity of water, available dissolved oxygen, biochemical oxygen demand, electrical conductivity etc. From background reviewing, it came out that almost 90 percent among those 800 industries located on the both sides of Karnaphuli river bank have not completed and operated their Effluent treatment plant (ETP) and the owners of few industries who already claimed setting up of ETP is also not running every day[3]. Apart from resulting in temporary and permanent health hazards to human health the Directorate of Environment (DoE) says that according to a survey in , 76 species of indigenous fishes were available in the river which now has come down to only 10 varieties of 1 Department of Civil Engineering, Chittagong University of Engineering & Technology (CUET), Chittagong Assistant Professor, Department of Civil Engineering, Chittagong University of Engineering & Technology, Chittagong-4349, BANGLADESH, masudbuet93@yahoo.com

2 368 mixed water fish & 20 varieties of sweet water fishes[4]. The studies also depicts that the water quality has been degrading so fast that it is now posing a threat to the biodiversity of the Halda river, the river in Asia where migrated brood fishes of some indigenous species spams in a particular time of the year[3]. So the overall aim of this study is to assess the present water quality for different seasons of the year and thus showing comparison with the Bangladesh Standards for drinking water, recreational use, fish cultivation and irrigational use. 2. Materials & Methods 2.1 Selection of the Study Area The industries of Chittagong are mainly concentrated in the region between Kalurghat to Patenga. Hundreds of metric tons of dangerous effluents from around 800 different types of industries particularly 3 tanneries, 15 leather godowns, 2 chemical factories, 7 fish processing factories, 2 soap factories, one steel mill,2 paper mills, one beverage producing unit, 5 textile and dying factories, 2 giant fertilizer manufacturing enterprises and one cement factory are rolling-up to the River water as most of them, either do not have Effluent Treatment Plant (ETP) or kept inoperative the ETP technology in a bid to make more profit[3]. Table-1: The numbers & locations of industries responsible for water pollution of Karnaphuli river[8] Location No. of Industries Location No. of Industries Kalurghat 98 Dry-Dock 89 Mohra 85 Katgore 40 Chandraghona 10 Jaldia 30 Chaktai 76 Gohira 20 Sadarghat 71 Port 65 Firingibazar 60 Fisheryghat 60 Between this zones there are more than 20 khals (canals) which are directly connected to the river and disposing waste (directly or indirectly) into the river on a regular basis. From those connecting khals, 13 different khals had been selected for this thesis named Airport Khal, Anu Majhi Khal, TSP Khal, Salt Gola, Dokkhin Ghat, Rajakhali Khal, Chaktai Khal, Sikalbaha Khal, Tecsho Ghor, Hatdorpara, Boailla Khal, Rakkhali Khal & Ispahani Khal in d/s to u/s order. From those selected khals, water samples had been collected from the confluences of khal with the river. Fig 1 Sampling Locations for the Study (Patenga to Kalurghat)[7]

3 Sampling In order to evaluate the River water quality, samples have been collected from 13 different locations in two different seasonal periods of the year. Water Samples have been collected in both spatial and temporal basis. A range of water quality variables have been measured in this zone, for two different period of the year viz. Dry Period (November-April, ) and Wet Period (May- August, 2015) over a period of 10 months as 70percent of the total rainfall occurs during this period of the year. In total, 26 water samples have been analyzed over a period of November 2014 to August Laboratory Analysis Standard Lab test procedures have been followed to analyze the physic-chemical parameters of the collected water samples. Visual inspection for color, smelling for odor, ph meter for ph, EC meter for electrical conductivity and turbidity meter for turbidity, titrimetric for determination of DO, BOD 5, COD, alkalinity, salinity and gravimetric method for TDS, TSS and TS[2]. 3. Results and Discussions

4 370

5 371 From Fig 2 it can be stated that, the value of Turbidity for different analyzed varied between 34.7 NTU to NTU; where the minimum value obtained is from dry period and the maximum value obtained is from wet period. The turbidity value increases during wet period and the d/s zone sample water is more turbid than the u/s side due to surface run off and more sewage and effluent dumping from industries. The value of Alkalinity lies between 45 mg/l to 240 mg/l (Fig 3), where the concentration is maximum during the dry period and reduces during the wet period due to precipitation. Fig 4 shows that, the EC concentration is higher during the dry period. The maximum obtained value is 10240µmhos/cm and the sampling locations closer to the estuary have higher values of EC than the u/s side due to tidal effect. During the dry period most of the d/s points deviates largely from the BD standard for discharge into inland and irrigated land which are both 1200 µmhos/cm[5]. The salinity value is extremely high in those sampling locations near the estuary during the dry period, maximum of them is in Salt Gola khal 8150 mg/l (Fig 5). During the dry period maximum sampling locations have higher concentration values than BD standard for discharge in to in-land and irrigated land which are both 600 mg/l and drinking water standard mg/l[5]. The lowest one is from Sikalbaha, Ispahani Khal & Kalurghat during wet period which is 15mg/l. Fig 6 shows that, the concentration of DO is higher during the wet period and lower during the dry. The lowest DO obtained during wet period is 4mg/l is from Anu Majhi Ghat but it increases to 6mg/l during the wet

6 372 period. In most of the cases the obtained DO values satisfies BD standards for drinking water (6mg/l)[1] and fish culture, irrigation & recreational use which are all 5mg/l[5]. When it comes to BOD 5 the highest value is found during the dry period of the year in Airport Khal which is 24mg/l and the lowest value is during the wet period from Ispahani Khal 3mg/l (Fig 7). During the dry period of the year most of the samples show higher value than BD Standard for Fish culture (6mg/l), agriculture (10mg/l) and recreation (3mg/l)[5]. The TSS value is maximum during the wet period of the year due to surface run off and the highest concentration found is 11500mg/l at Dokkhin Ghat (Fig 8). During the wet period most of the samples have much higher values than BD Standard for in-land discharge (150mg/l) and discharge into irrigated land (200mg/l)[5]. Again from Fig 9 it can be said that, the TDS value is maximum in the locations near the estuary due to dissolved salts and it is higher during the dry period of the year. The maximum value of TDS is found in Dokkhin Ghat 3490mg/l during the dry period. During the dry period most of the d/s samples deviates largely from WHO & BD Standard for drinking water (1000mg/l)[1], BD standard for discharge into in-land (2100mg/l) & irrigated land (2100mg/l)[5]. 4. Conclusions From the overall analysis it became evident that all the water quality parameters apart from Turbidity and TSS increases highly during the dry period of the year. Alkalinity increases in the d/s zone thus making the water slightly alkaline. The DO remains in the BD Standard range during both the seasons which is a good sign. But BOD 5 & COD becomes higher during the dry period of the year, deviate from the Standards and thus pose threat to the aquatic life[4]. Again the Salinity and EC increases to a large extent during the dry period of the year which is very alarming for the aquatic and both human life. TDS is also very high during the dry period due to salinity. The Turbidity and TSS concentrations increase heavily during the wet period due to all those surface runoff that comes directly into the river due to heavy rainfall. Overall, the study shows that the d/s section of the river is found to be highly affected by the water pollution phenomenon as this zone is densely concentrated with industries, tanneries etc.[8]. The continuous waste dumping, sewage disposal, oil spilling from ships, overhanging latrines, wastes from slaughterhouses, continuous land grabbing etc. are making the situation more critical day by day. So, it is high time for the authority to focus on these problem sources and come forward with mitigating measures. 5. Acknowledgement The author wishes to express her profound gratitude and heartfelt appreciation to the Department of Civil Engineering, CUET to provide such a wonderful opportunity to complete this study. 6. References [1] Ahmed, M.F. and Rahman, M.M Water Supply & Sanitation: Rural and Low Income Urban Communities, ITN- Bangladesh, 4 th Edition, pg , [2] APHA, AWWA, WEF (2005), Standard Methods for the Examination of Water and Wastewater, 21 st edn., American Water Works Association (AWWA) and Water Environment Federation (WEF), Washington, DC, USA. [3] Bangladesh Sangbad Sangstha (BSS), Existence of Karnaphuli at stake for encroachment & pollution, June 21, 2015, Chittagong. [4] DoE. (2001), The General over view of pollution status of Rivers of Bangladesh, Department of Environment, Dhaka, Bangladesh. [5] GOB (1997), Environmental Conservation Rules-1997, Gazette Notification, Ministry of Environment & Forests, Govt. of People s Republic of Bangladesh, 27 th August, 1997.

7 373 [6] maps.google.com, Karnaphuli river, Chittagong, Bangladesh (Last access: 16 th September, 2015). [7] Majid, M.A and Sharma, S.K, (1999), A study of water quality parameter of the Karnafully River, J. Ban. Chem. Sec, 12(1): [8] Sarwar, M.I; Majumder, A.K & Islam, M.N, "Water Quality Parameters: A Case Study of Karnaphully River Chittagong, Bangladesh", Bangladesh J. Sci. Ind. Res. 45(2), , 2010.