Water quality, pollution and treatment units

Water Quality, Pollution, and Treatment Plants Objectives • Introduce water quality standards • Introduce typical treatment processes and design flow rates • Present examples of flow sheet diagrams Water Usage  Domestic  Industrial  Agriculture  Fish farming  Recreational Pollution Pollution Physical Physical Radiological Radiological •Thermal •Solids Chemical Chemical Biological Biological •Hardness •Pathogens •Heavy metals •Nutrients •Pesticides •Oxygen demanding waste •Volatile organic compounds •Radio-isotopes Storm water pollution Scale formation due to water hardness Red tide due to algae contamination Water Quality Standards • • • • A Standards for water usage B Discharge or effluent standard C Water quality objective limit Drinking Irrigation Recreational Industrial • • • • • • • • Stream Sea Harbor Lake Stream Sea Harbor Lake A Drinking Water Standard A1 US Primary Drinking Water MCL in mg/L (partial list) Inorganic Chemicals Arsenic 0.05 Mercury 0.002 Barium Nickel 0.1 Cadmium 0.005 Nitrate (as N) 10 Chromium (total) 0.1 Nitrite (as N) Copper TT Nitrate + nitrite 10 Fluoride Selenium 0.05 Lead TT Thallium 0.002 Asbestos 7×106 fiber /L Ethylbenzene 0.7 Vinyl chloride 0.002 VOCs Benzene 0.005 Carbon tetrachloride 0.005 Different countries may have different drinking water standards A2 Bacteriological limits for drinking water US EPA states that “bacterial quality criteria for drinking water from public supplies require not more than total-coliform/100 ml as the arithmetic mean of all water samples examined per month, with no more than coliforms/100 ml in any sample if the number of samples is ≤ 20/month, or no more than per 100 ml in 5% of the samples if the number of samples exceeds 20 per month Bouwer, Groundwater Hydrology, McGraw-Hill, 1978 Number of samples taken for coliform testing depends on the population served by the treatment facility Example Water samples from the effluent of a water treatment plant of a town (39,000 people) were analyzed at regular intervals over a month period The numbers of coliform/100 ml sample were as shown below: According to EPA regulations, are the number of samples and effluent bacterial quality acceptable? Explain .No Count No Count No Count No Count 11 21 31 12 22 32 13 23 33 14 24 34 15 25 35 16 26 36 17 27 37 18 28 38 19 29 39 10 20 30 40 Solution The population is 39,000, so the minimum number of samples should be 40 Since we have 40 samples then the number of samples taken is OK The arithmetic average of coliform should not be more than Since the average number of coliform is 0.95 which is less than then this condition is OK No more than 5% of the samples should have more than coliform/100ml Since the number of samples is 40 then no more than samples (5%) should have more than coliform/100ml However, there are three samples (sample # 14, 25, and 38) that have more than coliform/100ml So this is a violation of the regulations A3 Secondary Standard for Drinking Water Contaminant Level Effects Al 0.05-0.2 mg/L Water discoloration Cl 250 mg/L Taste, pipe corrosion Color 15 color units Aesthetic Cu mg/L Taste, porcelain staining F mg/L Dental fluorosis Foaming agents 0.5 mg/L Aesthetic Fe 0.3 mg/L Taste, laundry staining pH 6.5-8.5 Corrosive Sulfate 250 mg/L Taste, laxative effects B Effluent Standards B1 US National Pollutant Discharge Elimination System )(NPDES consecutive days 30 consecutive days BOD 45 mg/l 30 mg/l SS 45 mg/l 30 mg/l Oil and grease 20 mg/l 10 mg/l pH: 6-9 BOD and SS removal > 85% B2 Discharge standard of wastewater into Jebel Ali Harbor Parameter Unit Maximum limit Total Suspended solids mg/l 50 - 6-9 C < 35 BOD mg/l 50 Dissolved Oxygen mg/l >3 Nitrate mg/l 40 Arsenic mg/l 0.05 Cadmium mg/l 0.05 Copper mg/l 0.5 Lead mg/l 0.1 Mercury mg/l 0.001 Oil & Grease mg/l 10 Phenols mg/l 0.1 Total Organic Carbon mg/l 75 Cells/100ml 1000 pH Temperature Total Coliform o C Water Quality Objective Limits Jebel Ali Harbor water quality objective limits Indicator Standard (mg/l or as noted) Lead 0.05 Oil and grease Aluminum 0.2 Arsenic 0.01 Cadmium 0.003 Dissolved oxygen Not less than mg/l or 90% saturation Mercury 0.001 BOD5 10 Nitrate-N 0.5 Aromatic hydrocarbons 0.001 pH pH unit from background level or 6.5-8.5 Suspended solids 10 (mean), 25 (maximum) Temperature oC from background level Total dissolved solids 2% from background level Typical Treatment of Contaminants Parameter/Problem Treatment Process Large debris (particles) Screens (Physical) Settlable solids Grit chamber (Physical) Suspended solids Coagulation (Chemical)/flocculation (Physical)/Sedimentation (Physical) Filtration (Physical) BOD Biological reactors (Biological) Heavy metals Depending on the metal: Sorption (Chemical), ion exchange (Chemical), or precipitation (Chemical) Trace organic contaminants Activated carbon (Chemical) or air stripping (Chemical) if chemicals are volatile in nature Microorganisms Disinfection (mainly Chemical) (Water Treatment Plant (WTP A WTP consists of processes to remove contaminants present in the water such that produced water is suitable for drinking The design of a WTP depends on (1) the quality of raw water, (2) the quality of produced water and the (3) capacity of the plant The capacity of the plant depends on the design period (15-25 yrs), the population served, and the per capita water consumption A flow sheet for the plant shows the sequence of the processes used: Raw water Produced water influent Effluent WTP (Wastewater Treatment Plant (WWTP A WWTP consists of processes to remove contaminants present in the wastewater such that produced water is suitable for discharge or reuse The design of a WWTP depends on (1) the characteristics of wastewater, (2) the desired characteristics of treated wastewater and the (3) capacity of the plant The capacity of the plant depends on the design period (15-25 yrs), the population served, and the per capita wastewater generation A flow sheet for the plant shows the sequence of the processes used: Wastewater Treated wastewater or Or influent WWTP Effluent Flow Rates: Water Treatment Plants Design flow rate =per capita water consumption*population at the end of design period Note that the per capita water consumption increases about 10% of the percentage increase in population Example A small town with a population of 100,000 and a per capita water consumption of 500 L/d A water treatment plant is to be built to serve this town for the coming 10 yrs Estimate the design flow rate assuming the population after 10 yrs is 150,000 Solution The percent increase in population = (150000-100000)/100000= 50% Per capita consumption at the end of design period=500(100% +50%*10%)=525 L/d Design flow rate = 150,000 * 525 L/d= 78750 m3/d Flow Rates: Wastewater Treatment Plants :Minimum flow rate Important for design of pipes and channels that carry wastewater with suspended solids Minimum velocity to keep organic solids in suspension is 0.3 m/s and to keep silt and sand in suspension is about 0.6 m/s :Maximum flow rate This is the peak hourly flow Such flow is used to determine the hydraulic capacity of the treatment plant and collection system Design flow rate: Average daily flow at the end of the design period Usually the average daily flow is taken as the average over a continuous of 12 months period This design flow rate is used to determine organic loading and for sizing all treatment units Flow Sheet Diagram River Water Treatment Plant Coagulant Chlorine solution Raw water Effluent Bar Screen Traveling Mixing Screen Aeration Flocculation Settling Filtration Carbon bed Brine Add Mg + Add F Filter Bottle water Plant Ground Water Reverses Osmosis Filters G.L W.T Well Filter Ozonation Bottled Water Example Industrial Wastewater Treatment Plant Influent Equalization Tank Aeration Tank Settling Chlorination Tank Effluent Air Return sludge Dispersed plug-flow activated sludge plant for an industrial wastewater Removal Efficiency Q, Co Treatment Unit Q, C Q= flow rate Co = influent concentration C = effluent concentration Removal efficiency = (Co-C)*100/Co For example if Co is 100 mg/l and C is 10 mg/l then the removal efficiency of the treatment unit is 90% [...]... organic loading and for sizing all treatment units Flow Sheet Diagram River Water Treatment Plant Coagulant Chlorine solution Raw water Effluent Bar Screen Traveling Mixing Screen Aeration Flocculation Settling Filtration Carbon bed Brine Add Mg + Add F Filter Bottle water Plant Ground Water Reverses Osmosis Filters G.L W.T Well Filter Ozonation Bottled Water Example Industrial Wastewater Treatment Plant... sequence of the processes used: Raw water Produced water influent Effluent WTP (Wastewater Treatment Plant (WWTP A WWTP consists of processes to remove contaminants present in the wastewater such that produced water is suitable for discharge or reuse The design of a WWTP depends on (1) the characteristics of wastewater, (2) the desired characteristics of treated wastewater and the (3) capacity of the plant... Rates: Wastewater Treatment Plants :Minimum flow rate Important for design of pipes and channels that carry wastewater with suspended solids Minimum velocity to keep organic solids in suspension is 0.3 m/s and to keep silt and sand in suspension is about 0.6 m/s :Maximum flow rate This is the peak hourly flow Such flow is used to determine the hydraulic capacity of the treatment plant and collection... Chemical) (Water Treatment Plant (WTP A WTP consists of processes to remove contaminants present in the water such that produced water is suitable for drinking The design of a WTP depends on (1) the quality of raw water, (2) the quality of produced water and the (3) capacity of the plant The capacity of the plant depends on the design period (15-25 yrs), the population served, and the per capita water. .. period (15-25 yrs), the population served, and the per capita wastewater generation A flow sheet for the plant shows the sequence of the processes used: Wastewater Treated wastewater or Or influent WWTP Effluent Flow Rates: Water Treatment Plants Design flow rate =per capita water consumption*population at the end of design period Note that the per capita water consumption increases about 10% of the... staining pH 6.5-8.5 Corrosive Sulfate 250 mg/L Taste, laxative effects B Effluent Standards B1 US National Pollutant Discharge Elimination System )(NPDES 7 consecutive days 30 consecutive days BOD 45 mg/l 30 mg/l SS 45 mg/l 30 mg/l Oil and grease 20 mg/l 10 mg/l pH: 6-9 BOD and SS removal > 85% B2 Discharge standard of wastewater into Jebel Ali Harbor Parameter Unit Maximum limit Total Suspended solids... have more than 4 coliform/100ml However, there are three samples (sample # 14, 25, and 38) that have more than 4 coliform/100ml So this is a violation of the regulations A3 Secondary Standard for Drinking Water Contaminant Level Effects Al 0.05-0.2 mg/L Water discoloration Cl 250 mg/L Taste, pipe corrosion Color 15 color units Aesthetic Cu 1 mg/L Taste, porcelain staining F 2 mg/L Dental fluorosis Foaming... end of design period Note that the per capita water consumption increases about 10% of the percentage increase in population Example A small town with a population of 100,000 and a per capita water consumption of 500 L/d A water treatment plant is to be built to serve this town for the coming 10 yrs Estimate the design flow rate assuming the population after 10 yrs is 150,000 Solution The percent increase... Mercury mg/l 0.001 Oil & Grease mg/l 10 Phenols mg/l 0.1 Total Organic Carbon mg/l 75 Cells/100ml 1000 pH Temperature Total Coliform o C Water Quality Objective Limits Jebel Ali Harbor water quality objective limits Indicator Standard (mg/l or as noted) Lead 0.05 Oil and grease 1 Aluminum 0.2 Arsenic 0.01 Cadmium 0.003 Dissolved oxygen Not less than 5 mg/l or 90% saturation Mercury 0.001 BOD5 10 Nitrate-N...Example Water samples from the effluent of a water treatment plant of a town (39,000 people) were analyzed at regular intervals over a month period The numbers of coliform/100 ml sample were as shown below: According to EPA regulations, are the number of samples and effluent bacterial quality acceptable? Explain .No Count No Count No