University of Khartoum

Assessment Of Industrial Effluents IN khartoum

Assessment Of Industrial Effluents IN khartoum

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Title: Assessment Of Industrial Effluents IN khartoum
Author: Fathi Mohd, Sawsan
Abstract: This study is carried out at the Industrial Area of Khartoum North in the Khartoum state to determine the industrial effluents characteristics, their effect on sewers and their impact to the surrounding environment. Special attention has been given to tanneries effluents. In this study some factories, in the Industrial Area of Khartoum North, with different industrial types were selected for a closer study; their industrial operations and processing were observed, and their effluents were taken for physical and chemical analysis. The factories were: 1-Food Industry (Tahnia), Military Forces Factory. 2-Textiles, Sudanese Dyers Co. Ltd. 3-Pharmaceuticals, Amipharma. 4-Soaps and Oils, Soap and Allied Industries (Bittar). 5-Tanneries, Hibatan Tannery. Most of the factories in the Industrial Area of Khartoum North have no pretreatment units for the treatment of their effluents and therefore characteristics of wastewater flowing to the pubic sewerage system are not conforming with the standard limits. The analyses were performed to measure the characteristics of these industrial effluents: they include physical tests like: colour, odor, temperatures, and chemical tests like: pH, BOD, COD, SS, TDS, Chrome content, and dissolved sulphides tests. The results of the physical and chemical tests showed different degrees of pollution for different industries. These results were compared with THE INDUSTRIAL LOCAL ORDER FOR KHARTOUM NORTH OF 1971 together with the limits used by INDUSTRY DEVELOPMENT ORDERS of the nineties. Pharmaceutical, textiles, and soap industries showed less pollution, while food industries and tanneries showed a great degree of pollution; they almost exceeded all the acceptable limits of 1971. Tanneries were selected for the design of the pretreatment unit plant. All tanning processes, chemicals used in each process, and the types of wastes (solid and liquid) produced in each stage were observed. The max number of the different types of skins (i.e. the batch), the amount of water used in the industry, and the amount of wastewater produced were calculated. Many other tanneries in Khartoum state were visited to know the different tanning processing used and also to see their pretreatment units. Almost all of these tanneries use the same operations and processes for the tanning, but unfortunately most of them have only physical treatment (screens and settling tanks) with no maintenance or cleaning intervals. No treatment for the chrome content or the dissolved sulphides is carried out; their effects to the man and environment are widely known. Afrotan tannery has relatively a more advanced pretreatment unit plant. A typical pretreatment unit plant is proposed for the tanneries effluents, it comprises: - A bar screen: this decreases the suspended solids in the effluent. - A lifting tank with a lifting pump of submersible type. - A Chrome (Cr) storage and precipitation tank, where calcium hydroxide is added. Aeration can be used to enhance the precipitation. All Cr and other heavy metals are precipitated as hydroxides in the process. A mobile helicoidally sludge suction pump is used to remove all the precipitated Cr sludge and transferred to the Cr sludge drying beds. BOD and COD are also reduced. - Equalization and sulphides oxidation tank: all effluents are collected in this tank, mixed together, neutralized and become a homogenous solution. A rotary vane blower and a system of air diffuser devices are used for aeration of the effluent to oxidize all the dissolved sulphides. BOD and COD are also reduced in the process. - Pit for eventual dosage of chemicals: poly, manganese sulphate, and iron chloride may be added to the effluent, just before the sedimentation tank, to enhance the settling of all the remaining suspended solids. - Sedimentation tank, Dortmund type: all the suspended solids are removed in this tank; BOD is also reduced by a great percentage. The mobile suction pump (used for the suction of Cr sludge above) is used to remove all the other settling sludge from the sedimentation tank and transfer it to the other sludge drying beds. - Drying beds: Cr drying beds and other sludge drying beds are used to dry the sludge for the removal of odors and for volume reduction. Cr can also be reused after its drying but it needs special separate system for the process. The construction of the effluent treatment plant cost lots of money, but here in this design, this problem is highly considered and overcomed. The proposed pretreatment unit plant will cost about 60,000 US.$. This is all done to enhance the construction of these plants to provide a clean effluent and hence a clean environment. A comparison is made with other designs prepared by the UNIDO, solving the problems of 7 tanneries in Africa. The designs were almost similar, depending on the situation. The cost varies between 100,000 and 250,000 US.$. This cost is really cheap compared with the great hazards that are caused by tanneries effluents.
Description: 64 Pages
URI: http://khartoumspace.uofk.edu/handle/123456789/9703
Date: 2015-04-27


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