ENVIRONMENTAL HEALTH ENGINEERING (CVE 815)-Module ii - Copy.pptx

ENVIRONMENTAL HEALTH ENGINEERING (CVE 815)-Module ii - Copy.pptx

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  CVE 815 3/5/2024 1 CVE815 Prepared by Engr. Ado Mohammed
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  Water, Uses andcontamination The main water uses are: • Domestic supply • Industrial supply • Commercial supply • generation of electricity • Irrigation • Navigation • Animal supply • landscape harmony • Preservation of aquatic life • dilution and transport of wastes • Recreation and leisure • breeding of aquatic species 3/5/2024 2 CVE 815 Prepared by Engr. Ado Mohammed
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  WATER QUALITY Water becauseof its properties as a solvent and its capacity to transport particles, incorporates in itself various impurities that characterise the water quality. Natural condition: The surface water quality is affected by runoff and infiltration resulting from rainfall. The impact of these is dependent on the contact of the water with particles, substances and impurities in the soil. Therefore, the incorporation of suspended solids (e.g. ions originating from the dissolution of rocks) occurs even when the catchment area is totally preserved in its natural condition. Interference of human beings: The interference of man manifests itself either in a concentrated form, such as in the discharge of domestic or industrial wastewater, or in a diffused form, such as in the application of fertilizers or pesticides onto the soil. Both contribute to the introduction of compounds into the water, thus affecting its quality. 3/5/2024 3 CVE 815 Prepared by Engr. Ado Mohammed
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  WATER POLLUTION Water pollutionis the addition of substances or energy forms that directly or indirectly alter the nature of the water body in such a manner that negatively affects its legitimate uses. 3/5/2024 4 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER WASTEWATER CHARACTERISTICS Physical characteristics A.Solids 1. Solids, varying from rags to colloids 2. TSS, Total Suspended Solids 3. TDS, Total Dissolved Solids 4. Volatile and Fixed Solids 3/5/2024 5 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. WASTEWATER CHARACTERISTICS Physicalcharacteristics cont. B. Other Physical Characteristics 1. Turbidity 2. Color 3. Temperature 4. Conductivity 3/5/2024 6 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. WASTEWATER CHARACTERISTICS ChemicalCharacteristics A. Inorganic Non-metallic Constituents 1. pH 2. Alkalinity 3. Nitrogen 4. Phosphorus 5. Sulphur 6. Gases e.g.: nitrogen, oxygen, carbon dioxide, hydrogen sulfide, ammonia and methane 3/5/2024 7 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. WASTEWATER CHARACTERISTICS ChemicalCharacteristics cont. B. Metallic Constituents 1. Cadmium 2. Chromium 3. Lead etc. C. Aggregate Organic Compound 1. BOD5 2. COD 3. Others e.g.: VOCs, Priority Pollutants 3/5/2024 8 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. WASTEWATER CHARACTERISTICS BiologicalCharacteristics 1. Pathogens 2. Bacteria 3. Protozoa 4. Fungi 5. Algae 6. Viruses 7. Helminths 3/5/2024 9 CVE 815 Prepared by Engr. Ado Mohammed
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  3/5/2024 10 CVE 815Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. Residual Management Inwastewater treatment processes some surplus sludge is produced. WHAT IS SLUDGE ? 3/5/2024 11 CVE 815 Prepared by Engr. Ado Mohammed
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  WASTEWATER CONT. Residual ManagementCont. The objective of residual management is: i. Reduction of water content. ii. Stabilization of sludge solids. iii. Reduction in sludge solids volume. 3/5/2024 12 CVE 815 Prepared by Engr. Ado Mohammed
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  STEPS IN SLUDGETREATMENT AND DISPOSAL Step 1 – Sludge Thickening The first step in the sewage sludge treatment plan is called thickening. In this step, the sewage sludge is thickened in a gravity thickener to reduce its overall volume, thus enabling the easy handling of the sludge. Dissolved air flotation is another alternative that can be used to effectively to thicken the sludge by using air bubbles to allow the solid mass to float to the top. 3/5/2024 13 CVE 815 Prepared by Engr. Ado Mohammed
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  STEPS IN SLUDGETREATMENT AND DISPOSAL Cont. Step 2 – Sludge Digestion This is a biological process in which the organic solids present in the sludge are decomposed into stable substances. This process also helps reduce the total mass of solids, while destroying any present pathogens to enable easy dewatering. The sludge digestion process is a two-phase process. In the first stage, the dry solid sludge is heated and mixed in a closed tank to enable anaerobic digestion by acid- forming bacteria. These bacteria hydrolyze the large molecules of proteins and lipids present in the sludge and break them down into smaller water-soluble molecules, which they then ferment into various fatty acids. The sludge then flows into the second tank where it is converted by other bacteria to produce a mixture of carbon dioxide (CO2) and methane, after which the methane is collected and reused to power the digestion tank and generate power (depending on the quantity retrieved). 3/5/2024 14 CVE 815 Prepared by Engr. Ado Mohammed
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  STEPS IN SLUDGETREATMENT AND DISPOSAL Cont. Step 3 – Dewatering After retrieving useful gases and other byproducts, the remaining sludge is then dewatered before final disposal. In most cases, dewatered sludge usually contains a significant amount of water, as much as 70 percent, in spite of its solidified state. Therefore, it is important to dry and dewater the sludge beforehand. While using sludge-drying beds is the most common way to carry out this process, it is extremely time-consuming. In order to quicken these processes, waste management plans are also employing solid-liquid separation devices to carry out this process. In fact, centrifugation is slowly becoming one of the most preferred methods of dewatering sludge. By passing the sludge through a centrifuge, it becomes easier to retrieve all the water and enable easier handling of the solid waste in shorter durations at reduced costs. Other alternatives include the rotary drum vacuum filter and the belt filter press. 3/5/2024 15 CVE 815 Prepared by Engr. Ado Mohammed
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  STEPS IN SLUDGETREATMENT AND DISPOSAL Cont. Step 4 – Disposal Once the sludge has been effectively dewatered, it can be buried underground in a sanitary landfill or can be used as a fertilizer (Manure), depending on its chemical composition. In cases where the sludge is too toxic to be reused or buried, you can simply incinerate the sludge and convert it into ash. It is some time also dumped into the sea. 3/5/2024 16 CVE 815 Prepared by Engr. Ado Mohammed