Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Selection of small water treatment systems for potable water supply to small communities Chris Swartz Ground Water Division Eastern Cape Branch 11 September 2020 1
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Outline • Water sources in South Africa • Water quality in South Africa • Typical water quality problems in groundwater • Treatment options • Classification of raw water types • Water quality standards • Selection of treatment options • Advanced water treatment processes • Water technology information sheets 2
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water sources in South Africa Surface water • Dams (reservoirs) • Rivers Groundwater • Springs • Wells • Boreholes Seawater (desalination) Treated wastewater • Secondary treated wastewater • Direct potable reuse • Indirect potable reuse • De facto reuse 3
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 4
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water quality in South Africa Variable turbidity (high after rain) Inland waters: (surface waters) Low colour Western area: High TDS groundwater Coastal waters: High colour (NOM) Low turbidity 5
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Typical water quality problems in groundwater • Salinity (TDS) • Hardness (calcium, magnesium) • Chloride • Sulphate • Nitrate • Fluoride • Iron and manganese • Arsenic • Colloidal material • Organic substances • Chemicals of emerging Concern (CECs) 6
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Microbiological water quality • Total plate count (heterotrophic) • Pathogens • Indicator organisms: • coliforms • Total coliforms • Faecal coliforms • Protozoan parasites • Giardia • Cryptosporidium 7
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Chemicals of emerging concern CECs EDCs DBPs TrOCs PPCPs POPs 8
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Chemicals of emerging concern • What are CECs? • Chemicals of Emerging Concern • Not always new chemicals, but chemicals with new found implications • An ever growing list of micro and macro chemicals, nano-particles and radio nucleotides 9
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Chemicals of emerging concern • Types of CECs • Pharmaceuticals and veterinary medicines • Prescribed and over-counter drugs • Endocrine disrupting compounds • An exogenous compound that mimics or block hormonal functions in the body • Personal care products • Active ingredients in cosmetics, fragrances, soap, insect repellents, toothpastes e.g. antiseptics (triclosan/triclocarban) • Flame retardants • Active ingredient incorporated into consumer products such as electronics, plastic and children's toys • Perflorinated and brominated substances • Used as dirt-repellent coatings, spray for leather and textiles • Pesticides and herbicides • Nanomaterials among others 10
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Chemicals of emerging concern What should be focused on (priority list for South Africa) Industrial chemicals Flame retardants, TDCPP and TCEP X-ray contract fluid, Iopromide PAH, Benzo(a)pyrene Pesticides, biocides and herbicides Atrazine, Terbutylazine, Imidacloprid and Simazine Natural chemicals Caffeine, 17 beta estradiol Pharmaceuticals and metabolites Antiretroviral drugs Lamivudine and Stavudine Anti-epileptic, Carbamazepine Anti-malarial drugs Cinchonidine and Cinchonine Analgesic, Paracetamol Antibiotic, Sulfamethoxazole Personal care products Anti-microbial, Triclosan Household chemicals and food additives Plasticiser, Bisphenol-A Transformation products By-product , N-Nitrosodimethylamine (NMDA) 11
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Legal requirements • Suitability for potable use • Measure of the value of the water • Standards (see SANS 241) • Risk to consumers 12
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water quality standards SANS 241 (2015) 13
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water quality standards SANS 241 (2015) 14
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water quality standards SANS 241 (2015) 15
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Water quality standards SANS 241 (2015) 16
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for low-turbidity water 17
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for water containing organics 18
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for brackish water 19
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for iron and manganese 20
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for hard and soft water 21
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for high nitrate water 22
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 23
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Treatment options for high fluoride water 24
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Grouping of water quality parameters GROUP A Group A substances are indicators of potential problems and should be frequently tested at all points in the water supply system, irrespective of the source of the water. (Free available (or residual) chlorine has to be measured only if the water has been treated with chlorine-based disinfectants). Electrical conductivity (total Conductivity is an indicator of total dissolved salts (TDS), and also dissolved salts) establishes if the water is drinkable and capable of slaking thirst. Faecal coliforms This is an indicator of the possible presence of disease-causing organisms. It establishes if water is polluted with faecal matter. pH Value (1) This has a marked effect on the taste of water and also indicates possible corrosion problems and potential copper, zinc and cadmium problems. Turbidity (2) This affects the appearance, and thus the aesthetic acceptability, of the water. Turbidity is commonly high in surface waters. Free available chlorine (Residual This is a measure of effectiveness of the disinfection of the water. chlorine) Residual chlorine is the chlorine concentration remaining at least 30 minutes after disinfection. There should be residual chlorine in the water, but if the concentrations are too high, it may impact an unpleasant taste and smell to the water. 25
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Grouping of water quality parameters GROUP B The presence/concentration of Group B substances should be determined before the water is supplied. The frequency of testing depends on the source and the treatment applied. Note that substances of concern due to pollution sources in the area, may have to be added to Group B. Nitrate & Nitrite These are common in groundwater (borehole) samples, particularly in areas of intensive agricultural activity, or where pit latrines are used. Severe toxic effects are possible in infants. Fluoride This is often elevated in groundwater in hot, arid areas. Can cause damage to the skeleton and the marking of teeth. Sulphate This is particularly common in mining areas. Causes diarrhoea, particularly in users not accustomed to drinking water with high sulphate concentrations. Chloride This is often elevated in hot, arid areas, and on the western and southern Cape coast (particularly in groundwater). May cause nausea and vomiting at very high concentrations. Arsenic This may be present in groundwater, particularly in mining areas. Can lead to arsenic poisoning. Total coliforms This provides an additional indicator of disease- causing organisms, and the effectiveness of disinfection. 26
Presentation Chris Swartz (Eng) GWD ECAPE e-Talk -11 Sept 2020 Grouping of water quality parameters GROUP C Group C substances should be tested for at point of use only in areas of the country where soft water of a low pH value is used. Cadmium This usually occurs along with zinc in acidic waters where it may have been dissolved from appliances. Copper This affects the colour of the water and can cause upset stomachs. Normally occurs only when copper piping is used to carry water with a low pH value. 27
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