Introduction to Water Quality, Parameter, Their Measurements & Significance

Introduction to Water Quality, Water Quality Parameters, Their Measurements and Significance

Strategic Planning and Managing Singapore Land Reclamation Activities

Water Quality – is always defined as related

to the intended beneficial use of the water e.g. a water body good enough for irrigation is not good enough for drinking → both have different requirements or characteristics.

It is not enough to say a water body is of good quality or bad quality, we need quantitative measurements to determine the quality → the quantitative measurements are known as water quality parameters.

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Water Quality

• • • • •

Related to beneficial use of water body Determine by physical, chemical & biological properties Can be defined by a range of certain variable These variables are known as water quality parameters To indicate a beneficial use of a water body requires analysis of certain water quality parameters Strategic Planning and Managing Singapore Land Reclamation Activities

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• •

•

Ranges of WQ parameters limit the type of beneficial use of the water body The water quality and the values of WQ parameters change due to natural and human activities The values of WQ parameters can be determined in situ (or in the field) and can be analysed in a laboratory

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Water quality assessment Can be performed by means of:  Field measurements – physical parameters, in situ parameters, hydrological properties  Chemical analysis of water – chemical parameters  Biological test – toxicity test  Biological measurements – biological parameters, diversity index

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Changes in water quality are reflected by changes in the biota.

The community structure in a given aquatic habitat can therefore be used as an indicator of water quality.

Changes in community structures, detected by biological surveillance, may be used to detect short-term and long-term trends in water quality.

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Water quality parameters → Can be specific or non-specific.

Specific = describe the specific type of chemical or biological species e.g. aromatic hydrocarbons, organochlorine pesticides, Cu, Zn, faecal coliform.

Non-specific = signify a given property of a group of chemicals or biological species e.g.

Conductivity, turbidity, TSS, TOC, BOD, COD, fish toxicity.

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Water quality parameters: Generally divided into three categories i.e.

1. Physical parameters 2. Chemical parameters 3. Biological & microbiological

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Examples of physical parameters: Turbidity Transparency Colour Odour Taste Conductivity Salinity Water temperature Soilds (TS, TSS, TDS) Strategic Planning and Managing Singapore Land Reclamation Activities

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Most of physical parameters namely temperature, conductivity, transparency, turbidity, salinity are measured in situ together with DO and pH. Relevant field meters are used for this purpose.

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Examples of chemical parameters: pH (alkalinity, acidity) Dissolved oxygen Oxygen demands (COD, BOD) Total organic carbon (TOC) Oil and Grease Nutrients (phosphates, nitrates, ammonia, Kjeldahl N) Metals and trace metals (Ca, Mg, K, Fe, Mn, Cu, Zn, Cd, As, Hg) Specific organic compounds (phenol, pesticides, hydrocarbon) Radioactivity (gross beta count) Strategic Planning and Managing Singapore Land Reclamation Activities

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Examples of biological parameters: Phytoplankton Zooplankton Chlorophyll Macrophytes Periphyton Bottom fauna (benthic organisms)

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Examples of microbiological parameters: Standard plate count Total coliform bacteria Faecal coliform bacteria Viruses Protozoa

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Physical parameters & their measurements:

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SCT Meter For Salinity, Conductivity & Temperature

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Turbidimeter – for turbidity measurement

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Secchi disc – for transparency

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Apparatus for TSS & TDS

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Field apparatus for TSS & TDS

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Chemical parameters & their measurements:

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• pH – Concentration of Hydrogen (Hydronium

Ion)

–

pH = - log10[H3O+]

– For sea water, pH ranges from 7.7 to

8.3

– For river water, generally about neutral.

The pH can be acidic or alkaline due to anthropogenic inputs and can be very acidic around peat swamps.

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pH meter

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Nutrients in Seawater 

Nutrients – Polyatomic compounds containing Nitrogen,

Phosphorus, Silicon – Nitrogen

– Ammonia (NH3+NH4+), Nitrite (NO2-),

Nitrate(NO3-) – Phosphorus – Phosphate (PO43- )

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Nitrate + Nitrite Drinking Water Standards(Primary) • Nitrate: 10 mg as N/ L • Nitrite: 1 mg N/L Health Concern • Blue Baby Syndrome- Methemoglobinemia Sources • Fertilizers • Human and Animal Waste • Non-anthropogenic sources (fixation, rock weathering) • Atmospheric Deposition Strategic Planning and Managing Singapore Land Reclamation Activities

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Phosphate

Phosphate will stimulate the growth of plankton and aquatic plants which provide food for larger organisms, including: zooplankton, fish, humans, and other mammals. Plankton represent the base of the food chain.

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Phosphate Initially, this increased productivity will cause an increase in the fish population and overall biological diversity of the system.

But as the phosphate loading continues and there is a build-up of phosphate in the lake or surface water ecosystem, the aging process of lake or surface water ecosystem will be accelerated (or may be eutrophication)

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Dissolved Oxygen (DO)

One of the most important WQ parameters for all water bodies.

DO has no direct impact on human health but utmost important for aquatic organisms. Generally, DO values of < 3.0 mg/l are not healthy for fishes except for the very hardy ones.

DO is also very important for biological treatment.

DO is required for the aerobic degradation of organic materials.

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DO DO can be determined by means of Winkler titration or direct measure using a DO meter. The accuracy depends on the correct calibration of the DO meter.

The saturation value of DO depends on temperature and pressure.

Example: at T = 20oC, DOsaturated = 9.0 mg/l.

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DO meter

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Multimeter • DO • Temperature • pH • Conductivity • Redox potential

Workshop on Water Quality & Managing Ecology Monitoring SelatReclamation Johor, 3 – 5Activities July 2006; Strategic Planning and SingaporeatLand EOC, UKM, 43600 Bangi, Selangor.

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Temperature Conductivity Salinity Specific Conductance Depth or Shallow Vented Level pH ORP TDS Open-channel Flow Nitrate-nitrogen, Ammonia/Ammonium-nitrogen, or Chloride Strategic Planning and Managing Singapore Land Reclamation Activities

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Metals Metals exist as dissolved components/compounds or in particulate forms (as suspended particles).

Based on the method of measurements, metals can be categorised as: â&#x20AC;˘ Total metals â&#x20AC;˘ Dissolved metals â&#x20AC;˘ Particulate metals

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Metals Total metals: Metals in unfiltered samples.

Samples were normally acidified with HNO3.

Dissolved metals: Filtered sample, through a 0.45 Âľm membrane filter. Samples were not acidified prior to filtration.

Particulate metals: Metals contained in precipitate or supended material on the 0.45 Âľm membrane filter.

Metal pollution normally refer to the presence of heavy or toxic metals such as Pb, Cd, As, Hg, Zn, Ni, etc.

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ORGANIC MATTER Organic matter which gives rise to demand in oxygen (i.e. DO) can be indicated by • Total Organic Carbon (TOC) • Biochemical Oxygen Demand (BOD) • Chemical Oxygen Demand (COD)

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TOTAL ORGANIC CARBON Organic carbon represents many different compounds and oxidation states.

Organic carbon in freshwaters arise from: â&#x20AC;˘ living materials (directly from plants photosynthesis or directly from terrestrial organic matter) â&#x20AC;˘ constituents of waste materials and effluents TOC can thus be a useful indication of the degree of organic pollution.

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Some TOC values: Surface water = <10 mg/I Ground water = <2 mg/I Municipal wastewater = 10 > 100 mg/I

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TOC consists of dissolved and particulate materials, i.e.

TOC = DOC + POC DOC and POC can be determined separately after filtering through a glass fibre filter, 0.7 Âľm pore size.

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Principle of method for TOC determination: Complete oxidation of carbon to CO2 by • combustion • chemical reaction • uv irradiation CO2 generated is then determined • volumetrically • thermal conductivity • CO2 electrode Strategic Planning and Managing Singapore Land Reclamation Activities

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TOC ANALYZERS

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COD (Chemical Oxygen Demand) A measure of the oxygen equivalent of the organic matter susceptible to oxidation by a strong chemical oxidant.

Chemical oxidant used: KMnO4 K2Cr207 ( more widely used)

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COD is widely used as a measure of the susceptibility to oxidation of the organic and inorganic materials present in water bodies and in the effluents from sewage and industrial plants.

This test allows measurement of a waste in terms of total quantity of oxygen require for oxidation to CO2 and H2O. Some values of COD: Unpolluted surface water Polluted surface water Industrial waste water

20 mg/l >200 mg/l 100-60,000 mg/l

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ANALYTICAL ASPECTS OF COD Sampling - glass bottle Analysis - immediately (if polluted) - within 24 hrs ( if cold or unpolluted) - preserved with H2S04 if deep frozen Method - reflux with K2Cr207 followed by titration with Fe (II). Known as an open reflux method.

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REFLUX APPARATUS FOR COD

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BIOCHEMICAL OXYGEN DEMAND (BOD) An approximate measure of the路 amount of biochemically degradable organic matter present in a water sample.

Defined by the amount of oxygen required for the aerobic micro-organisms present in the sample to oxidise/degrade the organic matter into a stable inorganic form.

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Some BOD values Clean water Raw sewage Treated sewage Industrial waste water

<2 mg/I 600 mg/I 20 - 100 mg/I up to 25,000 mg/I

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BOD Analytical aspects Two available methods: â&#x20AC;˘ The dilution method, standard method of APHA & EPA approved method. â&#x20AC;˘ The manometric method have been used by the sewage treatment plants but not yet approved by the EPA. Strategic Planning and Managing Singapore Land Reclamation Activities

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BOD Bottles

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DO Meter for BOD bottle

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Incubator for BOD Test

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The value of water quality data: Reliable, meaningful data is a valuable commodity  If you can’t or don’t measure it, you can’t manage it

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