Irrigation Water Quality PDF

CEI_221 IRRIGATION AND DRAINAGE ENGINEERING Lecture 6 Irrigation Water Quality By: Dr. Samia Abou El-Fetouh Part 1  WATER QUALITY PARAMETER Can be divided into three types: Physical Chemical Biological Physical Parameters a. Turbidity - measured in NTU (NTU)Nephelometric Tur...

CEI_221 IRRIGATION AND DRAINAGE ENGINEERING Lecture 6 Irrigation Water Quality By: Dr. Samia Abou El-Fetouh Part 1  WATER QUALITY PARAMETER Can be divided into three types: Physical Chemical Biological Physical Parameters a. Turbidity - measured in NTU (NTU)Nephelometric Turbidity unit (≈ppm) Source(s): - Inorganic compounds such as clay, sand - Organic compounds such as plant fibre, human waste Effect(s): - Aesthetic - Adsorption point/centre for chemicals and micro-organisms - Health aspect b.Odour and Taste Source(s): - Inorganic compounds such as minerals, metals, salts (all of them give taste to water but no odour) - Organic compounds from petroleum and/or degradation of organic matters. (odour and taste) Effect(s): - Aesthetic - Health problems [reaction from sources and other chemicals such as chlorine (Cl2)] c.Temperature- measured in o C or o F Source(s): - Effect from environment - Industrial activities - cooling system Effect(s): - Disturb biological activities such as micro-organism and aquatic life - Chemical properties such as the degree of gas solubility, density and viscosity d.Suspended solid - measured in mg/L Source(s): - Inorganic compounds such as clay, sand - Organic compounds such as plant fibre, human waste Effect(s): - Aesthetic - Adsorption point/centre for chemicals and micro- organisms - Health aspect Measurement of Total Solids (TS) Evaporate a known volume of sample to dryness and weigh the residue. The total solid is expressed as milligrams per litre (mg/L). Measurement of Suspended Solids (SS) Weigh a filter paper on an analytical balance. Place the filter paper on the filter apparatus. Apply vacuum and filter 100 mL (or a larger volume if total suspended matter is low) well mixed sample.  Dry the filter paper in an oven at 103oC to 105oC for at least 1 hour. After 1 hour, cool the filter paper in a desiccator and weigh. Repeat the drying cycle until a constant weight is attained or until weight loss is less than 0.5 mg. Suspended Solid (mg/L) = [(A-B) x 1000] / volume of sample Where: A = weight of filter paper + suspended matter B = weight of filter paper Total Solid (mg/L) = Suspended Solid (mg/L) + Total Dissolved Solid (mg/L) Chemical Parameters a.Total dissolved solid (TDS) - Solid left in water after the water is filtered and dried. Source(s): - Inorganic compounds - minerals, metals & gases - Organic compounds – product from degradation of organic matters, organic gas Effect(s): - Cause taste, colour and odour problems - Health aspect b. Organic compounds Definition : All organic compounds contain carbon in combination with one or more elements. Source(s): - Nature: fibres, vegetable oils, animal oils and fats, cellulose, starch, sugar. - Synthesis: a wide variety of compounds and materials prepared by manufacturing processes. E.g. DDT, polyvinylchloride. - Fermentation: Alcohols, acetone, glycerol, antibiotics, acids. Effect(s): Depletion of the dissolved oxygen in the water Destroying aquatic life Damaging the ecosystem Some organics can caused cancer Trihalomethane (THM-carcinogenic compound) are produced in water and wastewater treatment plants when natural organic compounds combine with chlorine added for disinfection purposes. c. Inorganic compounds Definition When placed in water, inorganic compounds dissociate into electrically charged atoms referred to as ions. All atoms linked in ionic bond. Can be classified into two: metal and non-metal i. Metal – Non toxic and toxic Non-toxic – Ca2+, Mn2+, Na+, Fe2+, Mg2+, Al3+, Cu2+, Zn2+ - dangerous for health if the concentration is high Source(s): Mineral, readily available from nature Effect(s): - Colour, odour, taste and turbidity - Deteriorate health (at high concentration) Toxic – As2+, Ba2+, Cd2+, Cr2+, Pb2+, Hg2+ Source(s): - Human activities such as mining and industries Effect(s): - Dangerous diseases such as cancer, and deformation in new born baby ii. Non-metal – e.g. Si4+, F- , Cl-, NO3- Source(s): Mineral Effect(s): - Diseases heavy metal, NO2- → “blue baby syndrome” - Aesthetic Si+4 → turbidity - Fluoride (F-) - Not good for health if it is taken in high concentration - Concentration of 1 mg/L is good for the growth of children teeth - Excessive concentration – colour on teeth and problem in bone growth d.Alkalinity Definition : The quantity of ions in water to neutralise acid or a measure of water strength to neutralise acid. Main constituents : bicarbonate (HCO3-), carbonate (CO32-), and hydroxide (OH-) ions. Source(s): - Mineral dissolved in water and air. - Human activities such as detergent (in wastewater), fertilizers, pesticide etc. Effect(s): - Non pleasant taste - Reaction between alkaline constituent and cation (positive ion) produces precipitation in pipe. e.Hardness Definition : A measure of “multivalent” cations in water such as Ca2+, Mg2+, Fe2+, Mn3+. Ca2+ and Mg2+ are very important Source(s): - Natural mineral on earth Effect(s): - Excessive soap usage - Precipitate form on hardware - Precipitate in pipe - temperature and pH increased Two kinds of hardness: Carbonate hardness Non-carbonate hardness PH of water  Biological Part 2  Content 1. Introduction 2. Water Quality 3. Water Resources in Egypt 4. Sources of Irrigation Water 5. Soil Salinity 6. Water Quality Parameters influences on Irrigation 7. Water infiltration rate 8. Toxicity 9. Bacterial contamination 10.Irrigation Water Quality Criteria 11.Management Practices for Using Poor Quality Water 12.Leaching requirements (LR) 13.Case Study  Introduction Water quality is determined according to the purpose for which it will be used. The important of measuring water quality parameters for irrigation water The suitability of irrigation water is mainly depends on the amounts and type of salts present in water. Irrigation water can contain considerable pollutants and still be used, if managed carefully Water quality refers to the chemical, physical and biological characteristics of water. -The parameters for water quality are determined by the intended use: Human consumption, Industrial use, or Fishing or agriculture  Water Resources in Egypt Nile River and Groundwater in Delta and Valley Deep Groundwater Drainage water reuse Rainfall and flash floods Unconventional sources of water: Wastewater reuse and Desalination Sources of Irrigation Water Underground Surface 1. Fresh 2. Recycled  Water Quality Parameters influences on Irrigation Turbidity – water cloudiness caused by suspended solids of clays, silts, sands, organic materials: Can fill irrigation canals, seal soil pores, clog irrigation systems Water temperature – limited concern to irrigators Except if cold enough to reduce growth Sodium content may seal soil pores, decrease infiltration rate Hardness Do, Biological Oxygen Demand, Chemical Oxygen Demand (BOD, COD) –measures of amounts of oxygen & chemicals dissolved in water High BOD’s – decreased oxygen availability High BOD water can kill fish, decrease soil oxygen Pesticides  Water infiltration rate Relatively high sodium or low calcium content of soil or water reduce the rate of infiltration to such an extent that sufficient water cannot be infiltrated to the crop adequately from one irrigation to the neat. - This occurs within few centimeters of the soil surface and linked to the structural stability. - When a high sodium surface is developed it weakens the soil structure. - The soil particles become finer and clog the soil pores  Toxicity - Certain ions (sodium, chloride or boron) from soil or water accumulate in a sensitive crop to concentration high enough to cause crop damage and reduce yield. - Toxic ions absorbed with water in significant amounts, and transported to the leaves and they accumulate during transportation.  Bacterial contamination Bacterial contamination of irrigation water is not a serious problem, unless the crops irrigated with highly contaminated water directly eaten, without being cooked. Cash crops like cotton. which are processed after harvesting, can, therefore, use contaminated waste waters, without any trouble.  Soil Salinity Soil salinity is a measure of the concentration of all the soluble salts in soil water, and is usually expressed as electrical conductivity (EC). The major soluble mineral salts are:- The cations: sodium (Na), calcium (Ca), magnesium (Mg), potassium (K). The anions: chloride (Cl), sulfate (SO4), bicarbonate (HCO3), carbonate (CO3), and nitrate (NO3). Hyper-saline soil water may also contain boron (B),selenium (Se), lithium (Li), silica (Si), fluorine (F), manganese (Mn), barium (Ba), and aluminum (Al), some of which can be toxic to plants and animals  Units of Soil Salinity Salinity is generally expressed as total dissolved Solids (TDS) in milligram per liter (mg/ l) or parts per million (ppm). SI units for EC are: milli Siemens per centimeter (mS/cm) or deci Siemens per meter (dS /m) old units mmhos/cm 1mmhos/cm =1 dS/m EC readings are usually taken and reported at a standard temperature of 25 C. No fixed relationship exists between TDS and EC, although a factor of 640 is commonly used to convert EC (dS /m) to approximate TDS.  Causes of Soil Salinity There can be many causes of salts in soils; the most common sources are listed below: Inherent soil salinity (weathering of rocks, parent material) Brackish and saline irrigation water Sea water intrusion into coastal lands Poor drainage systems and a rising water-table Overuse of fertilizers (chemical and farm manures) Dumping of industrial brine onto the soil Irrigation Water Quality Criteria Various criteria are considered in evaluating the quality of irrigation water namely: Salinity hazard Sodium hazard Salt index Alkalinity hazard Permeability hazard Specific ion toxicity hazards  SALINITY HAZARD The concentration of soluble salts in irrigation water can be classified in terms of Electrical Conductivity (EC) and expressed as dS m-1. There are four classes of salinity (C1, C2 and C3, C4). The classes C1 and C2 of water are considered suitable for irrigation purposes (no problem). C3 and C4 classes of water are not suitable for irrigation purpose (severe problems).  SODICITY HAZARD High concentrations of sodium are undesirable in water because sodium adsorbs on to the soil cation exchange sites, causing soil aggregates to break down, sealing the pores of the soil and making it impermeable to water flow. The sodicity hazard of irrigation water is usually evaluated by: Sodium Adsorption Ratio (SAR) Adjusted SAR Sodium to calcium activity ratio (SCAR) Sodium ratio Sodium Adsorption Ratio (SAR) United States Salinity Laboratory (USSL) staff introduced the concept of sodium adsorption ratio (SAR) to predict sodium hazard. It is calculated as The sodium hazard of irrigation water expressed through SAR does not take into account the effect of anionic composition. Sodicity hazard also classified as S1, S2, S3 and S4. Example 1 What is the classification of irrigation water having the following characteristics: Concentration of Na, Ca and Mg are 22, 3 and 1.5 milliequivalents per liter respectively, and the electrical conductivity is 0.20 dS/m at 25 oC? Management Practices for Using Poor Quality Water Application of gypsum (CaSo4) Fertilizer application Methods of irrigation Crop tolerance Method of sowing Drainage & Leaching  Leaching requirements (LR) For salt removing from the roots zone, more irrigation water will be required to percolate the root zone. Leaching requirements (LR) is the additional water applied for removing salt. Example 2  Case Study https://www.researchgate.net/publication/325994400_Study_of_the_Quality_ of_Irrigation_Water_in_South-East_El-Kantara_Canal_North_Sinai_Egypt  The study examines the irrigation water quality for North Sinai Development Project (NSDP). The water resources investigated are agriculture wastewater mixed with Nile freshwater in a ratio of 1:1. This study focuses on the quality of irrigation water used in the reclamation and cultivation of 75,000 acres of the South-East EL-Kantra Canal lies in the NSDP. Six monitoring locations along the canal path were chosen for examination. Water samples were collected every month during the period from Dec. 2007 to Nov. 2014. The water parameters were set using the Egyptian irrigation water standards, as well as the United States Environmental Agency, USEPA Guidelines for reclaimed water quality for irrigation. II. WATER QUALITY PARAMETERS Total Dissolved Solids (TDS) Sodium Adsorption Ratio (SAR) Hydrogen concentration (pH) Nitrate (No3) Dissolved Oxygon (DO) Biological Oxygen Demand(BOD) Fecal coliforms (FC), Total coliforms (TC)  The results of the study clearly demonstrate restrictions to irrigate the uncooked vegetables and uncooked crops for human. The need for increasing the mixed Nile freshwater portion or pretreatment of the agriculture wastewater prior to mixing with the Nile freshwater to satisfy Egyptian irrigation water standards and USEPA 2012 , as several water quality results, such as BOD, DO, and fecal coliform, are unacceptable. As a suggestion, we recommend using aerated lagoons, stabilization ponds or wetlands to treat polluted agriculture wastewater before adding to the Nile river water to satisfy Egyptian irrigation water criteria.