Use a block diagram and brief notes to provide a step-by-step description of a conventional potable water treatment plant. (3 pages maximum)(20 marks) Question 2 The new Goreangab Reclamation Plant (Namibia) incorporates the following established and new treatment processes: Briefly describe each process and include reaction equations where necessary. (3 pages maximum)(30 marks) Powdered activated carbon (PAC), acid, polymers (used as and when required) •Pre-Ozonation •Coagulation/flocculation •Dissolved air flotation (DAF) •Rapid sand/Anthracite filtration •Ozonation •Biological activated carbon (BAC) filtration/adsorption •Granular activated carbon (GAC) filtration/adsorption •Membrane ultra-filtration •Chlorination/stabilization •
Distribution Powdered activated carbon (PAC) is used in the water treatment process to absorb organic matter. It may also occasionally cause bad smells or tastes in the drinking water. Pre-ozonation is when the gas released from the main zonation step of the water treatment process in the plant is captured and introduced in into the influent of raw water. Releasing this ozone directly into the raw water assists in breaking down long-strained organic matter as it is a strong oxidizing agent and this makes removal in later processes easier. Coagulation occurs when the water is destabilised by adding coagulants (chemicals) to the water, the small particles of pollutants then flock or cling together (flocculation) to form larger particles which make it easier to remove the pollutants.
The Term Paper on Microporosity And Surface Functionality Of Activated Carbon
Abstract Activated carbons have been prepared from jute stick by both chemical and physical activation methods using ZnCl2 and steam, respectively. The activated carbons were characterized by evaluating surface area, iodine number, pore size distribution, surface functional groups and surface textural properties. Based on the analysis, the activated carbon prepared by chemical activation method, ...
Dissolved air flotation (DAF) is when micro-fine air bubbles are pumped through the water pushing fine suspended materials apart and then pushing it to the surface where it can be removed easier. Rapid sand filtration is the process whereby the water is fed through a sand bed acting as a filter further removing more suspended particles. Ozonation is the main oxidizing step where ozone is pumped through the water further breaking down long-strained particles to make them easier to consume during the BAC step. Ozonation also destroys pathogens which can not be removed by chlorination.
Biological activated carbon (BAC) filtration / absorption is carbon granules which contain living microorganisms which consume organic particles as food further removing organic material from the water. Granular activated carbon (BAC) filtration / absorption further assists in the removal of solids by feeding the water through granular carbon which removes most of the dissolved organic carbon. Membrane ultra-filtration is when the water is forced through a membrane of myriad small tube, which walls are like sieves of the size 0. 35 micron and it retains all suspended matter larger than this pore size. Chlorination / stabilization is when chlorine is added to the water to disinfect it and the the water is stabelised by conducting a PH-correction to ensure the water does not corrode metal pipes. Distribution: After the treatment process approximate 30-35% of the treated water is blended with 70-75% of water from other sources and then it is distributed to consumers. Fig 1: A process diagram of the water treatment at Goreangab Reclamation Plant
Fig 2: Overall system layout at Goreangab Reclamation Plant Question 3 In a maximum 2 pages, distinguish among the following: •W. H. O. Guidelines for drinking water quality •South Africa’s SANS 241: 2006 •Catchment-specific water quality objectives (20 marks) The W. H. O guidelines for drinking quality was established in 1948, it promotes various functions such as improvement of nutrition, housing, sanitation, recreation, economic or working conditions focusing on physical health as well as environmental hygiene. The W. H. O. ublishes these guidelines in ten year intervals. The guidelines initially posted maximum concentration guideline values, International Standards as it were, in terms of microbial, chemical, radiological and physical constituents based on health assessments in these criteria. In the 1980’s however, the W. H. O. focus started to change in terms of these strict guideline values in which were in essence a prescriptive document to a more holistic approach for safe drinking water which concentrates more on localised relevant health based targets.
The Essay on Water Quality Carbon Dioxide
Water quality is a complex term to evaluate. The health of a water ecosystem depends on so many things. These parameters are each intertwined and connected. For simplicity there are several mainstream parameters that are used in conjunction with each other to determine the water s quality. These include: alkalinity, ammonia content, carbon dioxide, chlorine, nitrates, dissolved oxygen, phosphates, ...
This related to a more integrated risk assessment system and incremental risk management called water safety plans. These water safety plans allowed for the guidelines to be more of an operational plan instead of an international target that needed to be achieved. To be more precise, the application of these guidelines takes into account the socio-cultural, environmental and economic circumstances particular to a specific country in other words individual catchment assessment of a country.
This focus to individual catchment properties may be more long-term improvements in water quality than expensive treatment options, but it will be much cheaper, not such a large carbon footprint, more effective and more sustainable in the log run. Contrast to the holistic view the W. H. O. adopts, the SANS specification SANS 241:2006 adheres to a specific set of testing requirements in terms of drinking water quality based on the earlier guidelines set out by the W. H. O. Another difference is that W. H. O. focuses on the worldwide improvement of drinking water quality, whereas the SANS 41:2006 is only applicable to South Africa. The SANS specification does not look at individual catchment properties and in many parts of South Africa the requirements laid down by the SANS standard is not necessarily possible or practical to implement. The Department of Water Affair (DWA) however does apply the holistic approach of the W. H. O. by means of catchment-specific water quality objectives. They do however still take into account the requirements set out by the SANS specification, but try to achieve it in alternative practical catchment related plans where it can not be applied directly.
The Essay on Water Quality and Contamination 2
Introduction Background- The ever-increasing popularity of bottled water means that it is important to analyze not only its mineral content but also, above all, it’s content of possible contaminants, especially the organic ones. In this respect, bottled waters are a special case, because apart from organic chemical contaminants derived from the well from which they were acquired, their secondary ...
In the DWA paper presented at the Biennial Conference of The Water Institute of Southern Africa (WISA), ‘Water quality management of the upper Vaal Water Management Area: Status vs Water Quality Objectives’ it states the following: “The formulation of catchment specific water quality objectives provides the opportunity for stakeholders to express their needs in terms of water quality requirements and the opportunity to outline the need to dispose of waste. The formulation of water quality objectives furthermore provides a common, feasible and balanced approach to water quality management.
It provides the framework within which localised actions can contribute to a common goal i. e. sustainable resource utilisation, taking cognisance of the environment as a legitimate water user. The water quality objectives provide a measure against which the status of a specific resource can be gauged. This measure can be linked to specific time frames to enable revision, and because it is quantifiable, effective monitoring of the resource and informative decision making is enabled. ” (Van Jaarsveldt D & Maree D, May 2002)
