Water Pollution In Danube – Tisa – Danube Canal, Becej – Bogojevo Section

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Photo Credit: Greenfudge

Article courtesy of Jovan Vujnovic | July 22, 2015 | Greenfudge | Shared as educational material

Danube – Tisa – Danube canal is one of the largest complex systems built in Europe after the Second World War. It covers the northern part of Serbia – the territory of Vojvodina, with the total area of about 12,700 km2. The total length of the dug main canals is 960 km, including new and old canals and streams which were completely or partially reconstructed and thus included in the new system. In the basic canal network there are 51 structures – 24 gates, 16 waterlocks (for navigation 1,000 to 1,300 tons capacity), 5 safety gates, 6 pumping stations, and 180 bridges. This network allows drainage of about 700,000 ha and irrigation of about 50,000 ha.

Potentially navigation is possible on 664 km of canals. The navigational canals are second to fourth category according to EEC categorization. There are 14 goods ports on the canals. On the new canals of the water system the Danube-the Tisa-the Danube there were built: 84 bridges – 62 carriageway, 19 railway and 3 pedestrian ones.

One of the most important structures within this water system is the dam on the river Tisa near Novi Bečej which regulates the water regime in the basic canal network in Banat, for irrigation of about 300,000 ha. It is a concrete dam with 7 weir overflows and well chambers 24.×8, 0 m. It includes the waterlock of dimensions 85.0×12.0×3.0 m. The total dimension of the concrete dam part is about 214.0 m. The capacity of the outlet structures on the dam is Q0.3% = 4, 70 m3/s.

Sources of the water pollution come mainly from anthropogenic activity, like industry. Disturbances in ecosystem have grown through time because of regular wastewater discharges from chemical and petrochemical industry. These branches of the industry are considered most serious water pollutants, because there are very little cheap techniques that can be used to eliminate the pollution from the water. (Dalmacija and Agbaba, 2008).

In Danube – Tisa – Danube canal, there is a constant wastewater discharge from communal sources like homes and from the factories that are located in the urban areas that the canal flows through. Biggest number of pollutants is located on the part of the canal that is called DTD Vrbas – Bezdan, in which the wastewater is discharged directly or indirectly. On that part of the canal, there are three bigger urban areas: Vrbas, Kula and Crvenka, and each of them has bigger or smaller scale industry that accounts for much of the wastewater discharge.

Also on this part of the canal there are few little towns that don’t have canalization network, so they are also accounted to the direct sources of the pollution. From these places primary source of the water pollution is the human waste that flows in the canal untreated and unregistered.

In 2012, samples of surface and wastewater were taken. Sampling of the wastewater was done following the regulations for water sampling that were described in SRPS ISO 5667-10:2007 directive. The composite samples were taken in time intervals of two hours (the water in the final sample was the mixture of the samples that were taken every fifteen minutes in two hours).

Sampling of the surface waters was done following the standard procedure SRPS ISO 5667-4:1197. All the samples were conserved and transported to the lab, according to the guidance for sampling and managing of the samples for surface water SRPS ISO 5667-3.

In the table below there is a list of the sources of water pollution on this part of the canal.

 

Table 1. Sources of the water pollution for canal DTD.
NAME OF THE POLLUTANT ACTIVITY RECIPIENT WASTEWATER TREATMENT
Meat factory Carnex Vrbas Food industry DTD Vrbas-Bezdan Tertiary
Farmacoop Vrbas Agriculture DTD Vrbas-Bezdan Primary
Farm Savino Selo Agriculture DTD Bečej-Bogojevo Primary
Medela Vrbas Food industry DTD Vrbas-Bezdan None
Vital Vrbas Food industry DTD Vrbas-Bezdan Secondary
Public Utility Company (PUC) Standard Vrbas Utility DTD Bečej-Bogojevo None
PUC Komunalac Kula Utility DTD Vrbas-Bezdan None
PUC for water supply Crvenka Utility DTD Vrbas-Bezdan None
Jaffa Crvenka Food industry DTD Vrbas-Bezdan Secondary
Sugar Factory Vrbas Food industry DTD Vrbas-Bezdan Primary
Sugar Factory Crvenka Food industry DTD Vrbas-Bezdan Primary
Reahem Srbobran Food industry DTD Vrbas-Bezdan Primary
PUC Graditelj Srbobran Utility DTD Bečej-Bogojevo None

 

The goal of the sampling and data processing was to determine the effects of wastewater discharges and their impact on Canal Bečej – Bogojevo. In that purpose an analysis of wastewater and surface waters was done. Based on the results of an analysis, the amount of pollutants that is discharged in canal every day with the wastewater was calculated. Given values were then compared with the Serbian regulative.

Primary (mechanical) treatment is designed to remove gross, suspended and floating solids from raw sewage. It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids. This level is sometimes referred to as “mechanical treatment”, although chemicals are often used to accelerate the sedimentation process. Primary treatment can reduce the BOD of the incoming wastewater by 20-30% and the total suspended solids by some 50-60%. Primary treatment is usually the first stage of wastewater treatment. Many advanced wastewater treatment plants in industrialized countries have started with primary treatment, and have then added other treatment stages as wastewater load has grown, as the need for treatment has increased, and as resources have become available.

Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction. The biological process is then followed by additional settling tanks (“secondary sedimentation”, see photo) to remove more of the suspended solids. About 85% of the suspended solids and BOD can be removed by a well running plant with secondary treatment. Secondary treatment technologies include the basic activated sludge process, the variants of pond and constructed wetland systems, trickling filters and other forms of treatment which use biological activity to break down organic matter.

Tertiary treatment is simply additional treatment beyond secondary! Tertiary treatment can remove more than 99 percent of all the impurities from sewage, producing an effluent of almost drinking-water quality. The related technology can be very expensive, requiring a high level of technical know-how and well trained treatment plant operators, a steady energy supply, and chemicals and specific equipment which may not be readily available. An example of a typical tertiary treatment process is the modification of a conventional secondary treatment plant to remove additional phosphorus and nitrogen.

 

Table 2. Load of the wastewater graded by pollutants.
Pollutant Suspended solids, kg/day COD, kg/day BOD kg/day Nitrogen, kg/day Phosphorus kg/day
Farm “Savino Selo” 41 1429 769 282 9,8
Farm “Farmacoop” Vrbas 64 1308 737 384 6,4
Farm “Bačko Dobro Polje” 80 64 29 82 /
Meat Factory Carnex 9 23 5,7 5,4 2,8
Oil refinery “Vital” Vrbas 363 8994 2160 109 18,1
Jaffa Crvenka 6 6,9 3,5 1,6 0,2
Confectionary factory “Jaffa” Crvenka 311 881 480 122 8,8
Sugar factory Vrbas 16 118 57 1,6 0,2
Biscuit factory “Medela” Vrbas 25 104 51 13 0,1
PUC Crvenka 38 1896 1044 126 1,3
PUC Vrbas 56 202 67 27 0,03
PUC Kula 7,7 49 22 1,8 0,5
PUC Srbobran 41 1429 769 282 9,8

 

Based on the data that are shown in the table above, it can be concluded that the biggest polutant is the Oil refinery “Vital” from Vrbas where the concentration of analyzed parameters is many times above the allowed concentrations that are defined in the Regulation on limit values of emission. From this industry the biggest load of pollutants is emitted, both in terms of organic matter composition and the nutrients composition.

In order to determine which activity of pollutants emits the biggest load of wastewater, pollutants were separated by activity and the sum of loads were shown.

 

Table 3. Loads of wastewater, graded by activity.
Activity Suspended solids, kg/day COD, kg/day BOD kg/day Nitrogen, kg/day Phosphorus kg/day
Industry 705 10023 2706 240 30
Urban waters 127 2251 1184 169 1,93
Agriculture – farms 185 2801 1535 748 16,2

 

Meat Factory Carnex 9 23 5,7 5,4 2,8
Oil refinery “Vital” Vrbas 363 8994 2160 109 18,1
Jaffa Crvenka 6 6,9 3,5 1,6 0,2
Confectionary factory “Jaffa” Crvenka 311 881 480 122 8,8
Sugar factory Vrbas 16 118 57 1,6 0,2
Biscuit factory “Medela” Vrbas 25 104 51 13 0,1
PUC Crvenka 38 1896 1044 126 1,3
PUC Vrbas 56 202 67 27 0,03
PUC Kula 7,7 49 22 1,8 0,5
PUC Srbobran 41 1429 769 282 9,8

Based on the data that are shown in the table above, it can be concluded that the biggest polutant is the Oil refinery “Vital” from Vrbas where the concentration of analyzed parameters is many times above the allowed concentrations that are defined in the Regulation on limit values of emission. From this industry the biggest load of pollutants is emitted, both in terms of organic matter composition and the nutrients composition.

In order to determine which activity of pollutants emits the biggest load of wastewater, pollutants were separated by activity and the sum of loads were shown.

 

Table 3. Loads of wastewater, graded by activity.

Activity Suspended solids, kg/day COD, kg/day BOD kg/day Nitrogen, kg/day Phosphorus kg/day
Industry 705 10023 2706 240 30
Urban waters 127 2251 1184 169 1,93
Agriculture – farms 185 2801 1535 748 16,2

 

Like the data in the table above shows, the biggest pollutant of surface water is the industry, and in this case because it is the food industry, it can be expected to find big amounts of organic matter in the water. It is primarily like this because the biggest amounts of wastewater are from industry and that contributes to the load. Besides that, most of the wastewater is discharged in the canal without any treatment at all.

 

Table 4. Loads of wastewater graded by the town from which they originate.
Town Suspended solids, kg/day COD, kg/day BOD kg/day Nitrogen, kg/day Phosphorus kg/day
Vrbas 801 13220 4484 748 38
Kula 56 202 67 27 0,03
Crvenka 31 111 55 14,7 0,3
Srbobran 7,7 49 22 1,8 0,5

 

Considering the data shown in the table 4, it can be seen that the biggest pollutant is the town of Vrbas, in which the most of the pollutants are located, followed by the towns of Kula, Srbobran and Crvenka. When it is taken in consideration that the towns of Vrbas and Kula together have 22 industrial plants, then some load of organic matter is expected, but the data shows that there is a much bigger load than the expected one, so it is required to remove it as soon as possible, in order to protect the environment and the health of people.

This pollution is highly concentrated and it is originated from few kilometers of distance from each other, which has been exacerbated with the low flow of water in canal. The biggest number of these pollutants discharges it’s wastewater in lateral canal which then flows in DTD Bečej – Bogojevo canal.

Biggest number of pollutants are located in big towns near the canal (Vrbas, Kula, Crvenka, and Srbobran). During the 2012, on the part of the canal of interest through the wastewater there was a daily discharge of big loads in canal. The loads in question were: 13, 6 tons COD (Chemical oxygen demand); 4, 6 tons BOD (Biological oxygen demand); 792 kg of nitrogen; 39 kg of phosphorus and 896 kg of suspended matter. The data shows that the biggest pollutants are Vrbas and Kula.

Results of physical – chemical analysis show that the quality of the water in DTD Bečej – Bogojevo canal is unsatisfactory. By the national legislation, most of the parameters on the sampled locations exceed the maximum allowable values for the 2nd class of waterways (good water quality). Those parameters are: dissolved oxygen, BOD, nutrients (nitrogen and phosphorus). Most endangered locations are on the downstream of triangle and on the upstream of the Krivaja River. The best water quality is on the uppermost location of the upstream, Kucura River.

 

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