2 Constituents in Wastewater nd reuse facilities. and in the engineering r nt of environmental qualitv. To promot this understanding, the information in this cho er, (2)sampling and analytical procedures, (3)physical ter is presented in eight sections dealing with(1)an introduction to the constituents found in wastewat characteristics,(4)inorganic nonmetallic constituents, (5) metallic constituents,(6) aggregate organic constituents,(7)individual organic constituents and compounds, and( 8)biological characteristics 2-1 Wastewater Constituents Constituents found in wastewater The principal physical properties and the chemical and biological constituents of wastewater, and their sources,are reported in Tab 2-1. It biological characteristics are interrelated. For example, temperature, a physical property, affects both the amounts of gases dissolved in the wastewater and the biological activity in the wastewater Constituents of concern in wastewater treatment The important constituents of concern in wastewater treatment are listed in Tab 2-2. Secondary treatment standards for wastewater are concerned with the removal of biodegradable organics, total suspended solids and pathogens. Many of the more stringent standards that have been developed recently deal with the removal of nutrients, heavy metals, and priority pollutants. When wastewater is to be reused, standards normally include additional requirements for the removal of refractory organics, heavy metals, and in some cases, dissolved inorganic solids 2-2 Sampling and Analytical Procedures Proper sampling and analytical techniques are of fundamental importance in the characterization of wastewater. Sampling techniques, the methods of analysis, the units of measurement for chemical constituents, and some useful concepts from chemistry are considered below Sampling Sampling programs are undertaken for a variety of reasons such as to obtain(1)routine operating data on overall plant performance,(2)data that can be used to document the perfomance of a given treatment operation or process, (3)data that can be used to implement proposed new programs, and(4)data needed for reporting regulatory compliance. To meet the goals of the sampling program, the data collected must 1. Representative. The data must represent the e wastewater or environment being sampled. 2. Reproducible. The data obtained must be reproducible by others following the same mentation must be available to validate the sampling procedures. The data must have a known degree of accuracy and precision. Useful. The data can be used to meet the obiectives of the monitoring plan. Because the data from the analvsis of the samples will ultimately serve as a basis for implementing wastewater management facilities and programs. the techniques used in a wastewater sampling program must be such that representative samples are obtained. Table 2-1 Common analyses used to assess the constituents found in wastewa Test Abbreviation/ Use or significance of test results definition Total solids determine most suitable type of operations and Total volatile solids processes for its treatment Total fixed solids TFS I suspended solids TSS Volatile suspended solids Fixed suspended solids FSS Total dissolved solids TDS(TS-TSS) VDS
2-1 2 Constituents in Wastewater An understanding of the nature of wastewater is essential in the design and operation of collection, treatment, and reuse facilities, and in the engineering management of environmental quality. To promote this understanding, the information in this chapter is presented in eight sections dealing with (1) an introduction to the constituents found in wastewater, (2) sampling and analytical procedures, (3) physical characteristics, (4) inorganic nonmetallic constituents, (5) metallic constituents, (6) aggregate organic constituents, (7) individual organic constituents and compounds,and (8) biological characteristics. 2-1 Wastewater Constituents Constituents Found in Wastewater The principal physical properties and the chemical and biological constituents of wastewater, and their sources, are reported in Tab 2-1. It should be noted that many of the physical properties and chemical and biological characteristics are interrelated. For example, temperature, a physical property, affects both the amounts of gases dissolved in the wastewater and the biological activity in the wastewater. Constituents of Concern in Wastewater Treatment The important constituents of concern in wastewater treatment are listed in Tab 2-2.Secondary treatment standards for wastewater are concerned with the removal of biodegradable organics, total suspended solids, and pathogens. Many of the more stringent standards that have been developed recently deal with the removal of nutrients, heavy metals, and priority pollutants. When wastewater is to be reused, standards normally include additional requirements for the removal of refractory organics, heavy metals, and in some cases, dissolved inorganic solids. 2-2 Sampling and Analytical Procedures Proper sampling and analytical techniques are of fundamental importance in the characterization of wastewater. Sampling techniques, the methods of analysis, the units of measurement for chemical constituents, and some useful concepts from chemistry are considered below. Sampling Sampling programs are undertaken for a variety of reasons such as to obtain (1) routine operating data on overall plant performance, (2) data that can be used to document the performance of a given treatment operation or process, (3) data that can be used to implement proposed new programs, and (4) data needed for reporting regulatory compliance. To meet the goals of the sampling program, the data collected must be: 1. Representative. The data must represent the wastewater or environment being sampled. 2. Reproducible. The data obtained must be reproducible by others following the same sampling and analytical protocols. 3. Defensible. Documentation must be available to validate the sampling procedures. The data must have a known degree of accuracy and precision. 4. Useful. The data can be used to meet the objectives of the monitoring plan. Because the data from the analysis of the samples will ultimately serve as a basis for implementing wastewater management facilities and programs, the techniques used in a wastewater sampling program must be such that representative samples are obtained. Table 2-1 Common analyses used to assess the constituents found in wastewater Test Abbreviation/ definition Use or significance of test results Physical characteristics To assess the potential of reuse a wastewater and to determine the most suitable type of operations and processes for its treatment Total solids TS Total volatile solids TVS Total fixed solids TFS Total suspended solids TSS Volatile suspended solids VSS Fixed suspended solids FSS Total dissolved solids TDS(TS-TSS) Volatile dissolved solids VDS
otal fixed dissolved solids FDS Settleable solids To determine those solids that will settle by gravity in a pec o assess the performance of treatment processes Used to assess the guality of treated wastewater Light brown, gray y, black To assess the condition of wastewater(fresh or septic) Transmittance T Used to assess the suitability of treated effluent for UV disinfection TON To determine if odors will be a problem Temperature mportant in the design and operation of biolog ical rocesses in treatment facilities Conductivity Used to assess the suitabil ity of treated effluent fo Inorganic chemical characteristics NHat Used as a measure of the nutrients present and the degree of decomposition in the wastewater; the oxid ized forms can TKN be taken as a measure of the degree of oxidation Inorg phospnorus a measure of the acidity or basicity of an aqueous solution ΣHCO3“CO32+OHHA Chloride Cl To assess the suitabil ity of the wastewater for agricu Itura Sulfate SOa To assess the potential for the formation of odors and may ty of the waste sludge Metals As, Cd, Ca, Cr, Co, Cu, Pb, Mg Hg, M To assess the suitability of the wastewater for reuse and fo o, NL Se, Na, Zn toxicity effects atment Trace amounts of metals are mportant in biological treatment. To assess presence or absence of specific constituents len O2,CO2,NH3,H2SCH4 To assess presence or absence of specific gas Organic chemical characteristics ive-day carbonaceous CBODs A measure of the amount of oxygen required to stabilize a biochem ical oxyge waste biologically Ultimate carbonaceous UBOD(BODu, BODL) A measure of the amount of oxygen required to stabilize a biochemical oxygen biologically Nitrogenous oxygen NOD A measure of the amount of oxygen required to oxidize en in the wastewater to nitrate oxygen COD Often used as a substitute for the bod test Total organic carbon TOC Often used as a substitute for the bod test MBAS. CTAS To determine presence of specific organic compounds and compounds and classes to assess whether special design measures will be needed Biological characteristics MNP To assess presence of pathogenic bacteria and effectivenes Specific organisms Bairusescter ia, protozoa, helminth To assess presence of specific organ isms in connection
2-2 Total fixed dissolved solids FDS Settleable solids To determine those solids that will settle by gravity in a specified time period Particle size distribution PSD To assess the performance of treatment processes Turbidity NTU Used to assess the quality of treated wastewater Color Light brown,gray,black To assess the condition of wastewater(fresh or septic) Transmittance %T Used to assess the suitability of treated effluent for UV disinfection Odor TON To determine if odors will be a problem Temperature ℃ Important in the design and operation of biological processes in treatment facilities Density ρ Conductivity EC Used to assess the suitability of treated effluent for agricultural applications Inorganic chemical characteristics Free ammonia NH4 + Used as a measure of the nutrients present and the degree of decomposition in the wastewater;the oxidized forms can be taken as a measure of the degree of oxidation Organic nitrogen Org N Total Kjeldahl nitrogen TKN Nitrates NO2 - Total nitrogen TN Inorganic phosphorus Inorg P Total phosphorus TP Organic phosphorus Org P pH pH A measure of the acidity or basicity of an aqueous solution Alkalinity ∑HCO3 -+CO3 2-+OH- -H + A measure of the buffering capacity of the wastewater Chloride Cl- To assess the suitability of the wastewater for agricultural reuse Sulfate SO4 2- To assess the potential for the formation of odors and may impact the treatability of the waste sludge Metals As,Cd,Ca,Cr,Co,Cu,Pb,Mg,Hg,M o,Ni,Se,Na,Zn To assess the suitability of the wastewater for reuse and for toxicity effects in treatment.Trace amounts of metals are important in biological treatment. Specific inorganic elements and compounds To assess presence or absence of specific constituents Various gases O2,CO2,NH3,H2S,CH4 To assess presence or absence of specific gases Organic chemical characteristics Five-day carbonaceous biochemical oxygen demand CBOD5 A measure of the amount of oxygen required to stabilize a waste biologically Ultimate carbonaceous biochemical oxygen demand UBOD(BODu,BODL) A measure of the amount of oxygen required to stabilize a waste biologically Nitrogenous oxygen demand NOD A measure of the amount of oxygen required to oxidize biologically the nitrogen in the wastewater to nitrate Chemical oxygen demand COD Often used as a substitute for the BOD test Total organic carbon TOC Often used as a substitute for the BOD test Specific organic compounds and classes of compounds MBAS,CTAS To determine presence of specific organic compounds and to assess whether special design measures will be needed for removal Biological characteristics Coliform organisms MNP To assess presence of pathogenic bacteria and effectiveness of disinfection process Specific organisms Bairusescteria,protozoa,helminth es,v To assess presence of specific organisms in connection with plant operation and for reuse
ic unit chronic Tab 2-2 Principal constituents of concern in wastewater treatment Suspended solids uspended solids can lead to the development of sludge deposition and anaerobic conditions hen untreated wastewater is discharged in the aquatic environment Biodegradable organics ly of proteins, carbohydrates, and fats. Biodegradable org anics are measured most commonly in terms of BoD and COD. If discharged untreated to the environment their biological stabilization can lead to the depletion of natural oxygen Patho Communicable diseases can be transmitted by the pathogenic organisms that may be present Nutrients Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic env ironment, the nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amount on land, they can also lead to the pollution Priority pollutants rganic and inorganic compounds selected on the basis of their known or suspected carcinogenic ity, metogenicity, teratogen icity or high acute toxicity. Many of these compounds Refractory organics These organics tend to resist conditional methods of wastewater treatment. Typ ical examples include surfactants phenols, and agricultural pesticides Heavy metals Heavy metals are usually added to wastewater from commercial and industr ial activities and may have to be removed if the wastewater is to be reused Dissolved inorganIcs Inorganic constituents such as calcium, sodium, and sulfate are added to the orig inal domestic water supply as a result of water use and may have to be removed if the wastewater is to be There are no universal procedures for sampling: sampling progra st be tailored individually to fit each situation. Special procedures are necessary to handle sampling problems that arise when wastes vary considerably in composition Before a sampling program is undertaken, a detailed sampling protocol must be developed along with a quality assurance project plan( QAPP)(known previously quality assurance/quality control, QA/QC). As a minimum, the following items must be specified in the QAPP. Additional details on the subject of sampling may be found in Standard Methods 1.Sampling plan. Number of sampling locations, number and type of samples, time intervals(.g, real-time and/or time-delayed samples) 2. Sample types and size, Catch or grab samples, composite samples, or integrated samples, separate samples for different analyses(e.g, for metals). Sample size(i.e, volume)required 3. Sample labeling and chain of custody. Sample labels, sample seals, field log book chain of custody record, sample analysis request sheets, sample delivery to the laboratory, receipt and logging of sample, and assignment of sample for analysis 4.Sampling methods. Specific techniques and equipment to be used(e.g, manual, automatic, or sorbent 5. Sampling storage and preservation. Type of containers(e.g, glass or plastic), preservation methods, maximum allowable holding times 6.Sample constituents. A list of the parameters to be measured 7. Analytical methods. A list of the field and laboratory test methods and procedures to be used, and the detection limits for the individual methods If the physical, chemical, and/or biological integrity of the not maintained during interim periods between sample collection and sample analysis, a car performed sampling program will become worthless. Considerable research on the problem of preservation has failed to perfect a universal treatment or method, or to formulate a set of fixed rules applicable to samples of all types Prompt analysis is undoubtedly the most positive assurance against error due to sample deterioration When analytical and testing conditions dictate a lag between collection and analysis, such as when a 24 h composite sample is collected, provisions must be made for preserving samples. Current methods of sample preservation for the analysis of properties subject to deterioration must be used Probable errors due to deterioration of the sample should be noted in reporting analytical data Methods of Analysis The analy ses used to characterize wastewater vary from precise quantitative chemical determinations to 2-3
2-3 Toxicity TUa,TUc Toxic unit acute,toxic unit chronic Tab 2-2 Principal constituents of concern in wastewater treatment Constituents Reason for importance Suspended solids Suspended solids can lead to the development of sludge deposition and anaerobic conditions when untreated wastewater is discharged in the aquatic environment. Biodegradable organics Composed principally of proteins, carbohydrates, and fats. Biodegradable organics are measured most commonly in terms of BOD and COD. If discharged untreated to the environment their biological stabilization can lead to the depletion of natural oxygen resources and to the development of septic conditions. Pathogens Communicable diseases can be transmitted by the pathogenic organisms that may be present in wastewater. Nutrients Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, the nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amount on land, they can also lead to the pollution of groundwater. Priority pollutants Organic and inorganic compounds selected on the basis of their known or suspected carcinogenicity, metogenicity, teratogenicity or high acute toxicity. Many of these compounds are found in wastewater. Refractory organics These organics tend to resist conditional methods of wastewater treatment. Typical examples include surfactants, phenols, and agricultural pesticides. Heavy metals Heavy metals are usually added to wastewater from commercial and industrial activities and may have to be removed if the wastewater is to be reused. Dissolved inorganics Inorganic constituents such as calcium, sodium, and sulfate are added to the original domestic water supply as a result of water use and may have to be removed if the wastewater is to be reused. There are no universal procedures for sampling; sampling programs must be tailored individually to fit each situation. Special procedures are necessary to handle sampling problems that arise when wastes vary considerably in composition. Before a sampling program is undertaken, a detailed sampling protocol must be developed along with a quality assurance project plan (QAPP) (known previously quality assurance/quality control, QA/QC). As a minimum, the following items must be specified in the QAPP. Additional details on the subject of sampling may be found in Standard Methods. 1.Sampling plan. Number of sampling locations, number and type of samples, time intervals (e.g., real-time and/or time-delayed samples). 2.Sample types and size, Catch or grab samples, composite samples, or integrated samples, separate samples for different analyses (e.g., for metals). Sample size (i.e., volume) required. 3.Sample labeling and chain of custody. Sample labels, sample seals, field log book, chain of custody record, sample analysis request sheets, sample delivery to the laboratory, receipt and logging of sample, and assignment of sample for analysis. 4.Sampling methods. Specific techniques and equipment to be used (e.g., manual, automatic, or sorbent sampling). 5.Sampling storage and preservation. Type of containers (e.g., glass or plastic), preservation methods, maximum allowable holding times. 6.Sample constituents. A list of the parameters to be measured. 7.Analytical methods. A list of the field and laboratory test methods and procedures to be used, and the detection limits for the individual methods. If the physical, chemical, and/or biological integrity of the samples is not maintained during interim periods between sample collection and sample analysis, a carefully performed sampling program will become worthless. Considerable research on the problem of sample preservation has failed to perfect a universal treatment or method, or to formulate a set of fixed rules applicable to samples of all types. Prompt analysis is undoubtedly the most positive assurance against error due to sample deterioration. When analytical and testing conditions dictate a lag between collection and analysis, such as when a 24 h composite sample is collected, provisions must be made for preserving samples. Current methods of sample preservation for the analysis of properties subject to deterioration must be used. Probable errors due to deterioration of the sample should be noted in reporting analytical data. Methods of Analysis The analyses used to characterize wastewater vary from precise quantitative chemical determinations to
the more qualitative biological and physical determinations. The quantitative methods of analysis are either gravimetric, volumetric, or physicochemical In the physicochemical methods, properties other than mass or volume are measured. Instrumental methods of analysis such as turbidimetry, colorimetry, potentiometry, polarography, adsorptio spectrometry, fluorometry, and nuclear radiation are representative of the physicochemical analyses Details concerning the various analyses may be found in Standard Methods, the accepted reference that details the conduct of water and wastewater analyses are defined and are listed below in order of increasing leve vel must be specified Several detection limits Units of Measurement for Physical and Chemical Parameters The results of the analysis of wastewater samples are expressed in terms of physical and chemical terms of measurement. The most common units for these measurements are, for example, kg/m, %by volume or by mass), pg/L, ng/L, ug/L, mg/L, g/L, ppb, ppm, mol/L, eq/L, meq/L and so on. The concentration of trace constituents is usually expressed as micrograms per liter(ug/L)or nanograms per liter(ng/L) For dilute systems, such as those encountered in natural waters and wastewater, in which one liter of sample weighs approximately one kilogram, the units of mg/L or g/mare interchangeable with ppm. The terms"parts per billion"(ppb) and"parts per trillion(ppt)are used interchangeably with ug/L and ng/L, espectively 2-3 Physical Characteristics The most important physical characteristic of wastewater is its total solids content, which is composed of floating matter, settleable matter, colloidal matter, and matter in solution Other important physical characteristics include particle size distribution, turbidity, color, transmittance, temperature, conductivity and density, specific gravity and specific weight Odor, sometimes considered a physical factor, is discussed in the following section Solids Wastewater contains a variety of solid materials varying from rags to colloidal material. In the characterization of wastewater, coarse materials are usually removed before the sample is analyzed for solids. The various solids classifications are identified in Tab 2-3. The interrelationship between the arious solids fractions found in wastewater is illustrated graphically on Fig. 2-1. The standard test for ttleable solids consists of placing a waste water sample in a l-liter Imhoff cone and noting the volume of lids in millimeters that settle after a specified time period (1 h Evaporation Typically, about 60 percent of the suspended solids in a municipal glass fiber TS solids (ts) are obtained by TSS= total susp evaporating a sample of wastewarer IDS- total disc to dryness and measuring the mass of fitrate FSS= fixed susE of the residue. As shown on Fig 2-1, VDS- volatile dis a filtration step is used to separate rys- toted diss the total suspended solids (TSS) TFS total fixed from the total dissolved solids (TDS). Filters with nominal pore from 0. 45 um to about 2.0 um have been used for the TSs FSS Fig. 2- Interrelationships of solids found in water and wastewater In much of the water TFS the solids through the filter are called dissolved solids
2-4 the more qualitative biological and physical determinations. The quantitative methods of analysis are either gravimetric, volumetric, or physicochemical. In the physicochemical methods, properties other than mass or volume are measured. Instrumental methods of analysis such as turbidimetry, colorimetry, potentiometry, polarography, adsorption spectrometry, fluorometry, and nuclear radiation are representative of the physicochemical analyses. Details concerning the various analyses may be found in Standard Methods , the accepted reference that details the conduct of water and wastewater analyses. Regardless of the method of analysis used, the detection level must be specified Several detection limits are defined and are listed below in order of increasing level. Units of Measurement for Physical and Chemical Parameters The results of the analysis of wastewater samples are expressed in terms of physical and chemical terms of measurement. The most common units for these measurements are, for example, kg/m3 ,%(by volume or by mass), pg/L, ng/L, µg/L, mg/L, g/L, ppb, ppm, mol/L, eq/L, meq/L and so on. The concentration of trace constituents is usually expressed as micrograms per liter (µg/L) or nanograms per liter (ng/L). For dilute systems, such as those encountered in natural waters and wastewater, in which one liter of sample weighs approximately one kilogram, the units of mg/L or g/m3 are interchangeable with ppm. The terms "parts per billion" (ppb) and "parts per trillion"(ppt) are used interchangeably with µg/L and ng/L, respectively. 2-3 Physical Characteristics The most important physical characteristic of wastewater is its total solids content, which is composed of floating matter, settleable matter, colloidal matter, and matter in solution. Other important physical characteristics include particle size distribution, turbidity, color, transmittance, temperature, conductivity, and density, specific gravity and specific weight. Odor, sometimes considered a physical factor, is discussed in the following section. Solids Wastewater contains a variety of solid materials varying from rags to colloidal material. In the characterization of wastewater, coarse materials are usually removed before the sample is analyzed for solids. The various solids classifications are identified in Tab 2-3. The interrelationship between the various solids fractions found in wastewater is illustrated graphically on Fig. 2-1. The standard test for settleable solids consists of placing a wastewater sample in a 1-liter Imhoff cone and noting the volume of solids in millimeters that settle after a specified time period (1 h). Typically, about 60 percent of the suspended solids in a municipal wastewater are settleable. Total solids (TS) are obtained by evaporating a sample of wastewarer to dryness and measuring the mass of the residue. As shown on Fig. 2-1, a filtration step is used to separate the total suspended solids (TSS) from the total dissolved solids (TDS). Filters with nominal pore sizes varying from 0.45 µm to about 2.0 µm have been used for the TSS test (see Fig. 2-2). Fig. 2-1 Interrelationships of solids found in water and wastewater. In much of the water quality literature, the solids passing through the filter are called dissolved solids
Tab 2-3 Definitions of solids found in wastewater Total solids(TS) The residue remain ing after a wastewater sa has been evaporated and dried cified 03 Total volatile solids(TVs) Those solids that can be volati led and off when the ts are ited(500±50℃) Total fixed solids(TFS he residue that remains after TS are ignited(500-50C) Total suspended solids(TSS) Portion of the ts retained on a filter with a specified pore size, measured after being dried at a specified temperature( 105C). The filter used most ommonly for the determination of is the whatman glass fiber 如 Those solids that can be volatilized and burned off when the TSS are ignit Fixed ded solids(FSS he residue that remains after tsS are ignited(500=+50 Total dissolved solids(TDS) Those solids that pass through the filter, and are then evaporated and dried at specified temperature. It comprised of collo idal and dissolved solids Colloids are typically in the size I Total volatile dissolved solids(VDS) Those solids that can be volatilized and burned off when the tds are ignited 500±50℃) Fixed dissolved solids(FDS) The residue that remains after TDS are ignited(500+50C) Settable solids Suspended solids, expressed as milliliters per liter, that will settle out of suspension within a s Synthetic organic compounds Algae, protozoa neutral pesticides/Pc Bacteria Cell fragmenta e. g, nitrogen. Organic debris Viruses (food and human wastes) Amino acids vitam Exocellular enzyn G-200 Sephadex G-15 Bio-Gel A150M High-pressure hquid chromatography Uitrafiltration molecular si HAC er light scatterin Approximate molecular mass. amu 01102103104105106107108109 Particle size, um Fig. 2-2 Size ranges of organic contaminants in wastewater and size separation and measurement techniques used for their quantification
2-5 Tab 2-3 Definitions of solids found in wastewater Test Description Total solids(TS) The residue remaining after a wastewater sample has been evaporated and dried at a specified temperature(103 to 105 ℃) Total volatile solids(TVS) Those solids that can be volatiled and burned off when the TS are ignited(500±50℃) Total fixed solids(TFS) The residue that remains after TS are ignited(500±50℃) Total suspended solids(TSS) Portion of the TS retained on a filter with a specified pore size, measured after being dried at a specified temperature(105℃).The filter used most commonly for the determination of TSS is the Whatman glass fiber filter ,which has a nominal pore size of about 1.58 μm. Volatile suspended solids(VSS) Those solids that can be volatilized and burned off when the TSS are ignited (500±50℃) Fixed suspended solids(FSS) The residue that remains after TSS are ignited (500±50℃) Total dissolved solids(TDS) Those solids that pass through the filter, and are then evaporated and dried at specified temperature. It comprised of colloidal and dissolved solids. Colloids are typically in the size range from 0.001 to 1μm Total volatile dissolved solids(VDS) Those solids that can be volatilized and burned off when the TDS are ignited (500±50℃) Fixed dissolved solids(FDS) The residue that remains after TDS are ignited (500±50℃) Settlable solids Suspended solids, expressed as milliliters per liter, that will settle out of suspension within a specified period of time Fig. 2-2 Size ranges of organic contaminants in wastewater and size separation and measurement techniques used for their quantification