For permission to photocopy or use material electronically from this work, please visit www.copyright.com(http://. www.copyright.com/) or contact the Copyright Clearance Center, Inc. Visit the Taylor & Francis website at http: ////www.taylorandfrancis.com and the CRC Press website at http://///www.crcpress.com.
Post-Treatment, Reuse, and Disposal
Historical Development
Human waste could now be diluted with large volumes of water, piped underground to a centralized location outside of population centers, and dumped into a large and suitable body of water. Various types of wastewater treatment technologies were developed and used: trickling filter in 1901, Imhoftank in 1909, liquid chlorine for disinfection in 1914 and activated sludge in 1916.
Current Status
A rule necessary to limit the TMDL of pollutants that a water body can accept and still maintain a margin of safety in meeting established water quality standards. The TMDL includes the total waste load from all point and nonpoint source (NPS) discharges and natural background levels. Early wastewater treatment goals were based primarily on total suspended solids (TSS), biochemical oxygen demand (BOD), and pathogenic organisms.
Future Directions
Wastewater characterization for computer modeling of biological nutrient removal (BNR) facility is given in Example 10.161. Among the innovative treatment methods are fine screens (sections and 9.7), vortex degritters (section 8.4.4), chemically enhanced primary treatment (CEPT) (section 9.5.2), high-velocity clarification (section 9.6), integrated fixed film activated sludge (IFAS) and moving bed biofilm reactor (MBBR) (Section 10.4.3), enhanced biological phosphorus removal (EBPR) and BNR processes (Sections 10.7 and 10.8), membrane bioreactors (MBR) (Chapter 10 and Section 10)4. , advanced oxidative processes (AOP) (Section 11.8), and innovative design and application of UV lamps for disinfection (Section 11.9).
Wastewater Treatment Plants
Testing and evaluation of these technologies by independent third parties will be encouraged and adapted. In addition, smart sensors, telemetry and remote sensing of water quality data will be developed and deployed.
Scope of This Book
Environmental Protection Agency, Stormwater Phase II Final Rule Fact Sheet Series, National Pollutant Discharge Elimination System (NPDES), https://www.epa.gov/npdes/stormwater- phase-ii-final-rule-fact-sheet-series (accessed on 18 November 2016). Environmental Protection Agency, National Menu of Best Management Practices (BMPs) for Stormwater, National Pollutant Discharge Elimination System (NPDES), https://www.epa.gov/ npdes/national-menu-best-management-practices-bmps-stormwater #edu ( accessed 18 November 2016).
Chapter Objectives
Stoichiometry
Consecutive or series reactions: In these reactions, the product of one step becomes the reactant of the subsequent reaction steps (Example 2.25). Reversible reactions: Reversible reactions are characterized by forward as well as reverse reactions occurring simultaneously (Example 2.9).
Reaction Rates and Order of Reaction
EXAMPLE 2.5: REACTION SEQUENCE AND UNITS OF REACTION RATE CONSTANT The overall reaction rate of a single reversible reaction is given by the equation: r=k[A][B]2. Determine the reaction rates for the reactant and each product as a function of the reaction rate constant and the molar concentration of A.
Effect of Temperature on Reaction Rate
Reaction Order Data Analysis and Design
This suggests that the reaction rate is dependent on the concentration of the remaining chemical. The semi-log plot of this equation will give a linear relationship, and the slope of the line is the reaction rate constant.
Chapter Objectives
Mass Balance Analysis
Draw the boundary of the system and identify the volumetric flow rates into and out of the system with arrows. The system boundary may take several flow lines and may have one or more flow lines. If a system boundary receives flow streams that also contain a conservative material, a mass balance analysis will include fluxes and concentrations.
Calculate (a) the degree of hardness capture in the softener, (b) the fractional flow to the softener, and (c) the bypass flow around the softener. Draw a process diagram and system boundaries around the treatment plant, softener and flow manifold (Figure 3.8). Calculate the air flow through the bag and the kilogram of dust collected per day in the bag.
Flow Regime
Types of Reactors
Plug Flow Reactors with Dispersion and Conversion
C0 is the average theoretical initial concentration of dye if it is completely mixed in the basin. The tracer concentration in the efflent in relation to time of sampling and other parameters is calculated in Table 3.7. The plotted values show that dead volume exists because the tracer concentrations in the experimental curve are lower than those in the theoretical curve.
The solution is expressed by Equation 3.40, which is independent of inlet and outlet conditions, and depends on distribution number (Equation 3.41).13. Thirumurthi developed Figure 3.34 to facilitate the solution of Equation 3.40.14 In this figure the dimensionless termkθ is plotted against percent C/C0 (residual) for distribution number varying from 0 for ideal PFR to infinity (∞) for an ideal CFSTR . A UV disinfection facility was designed for reducing the coliform count in the secondary effluent of a wastewater treatment plant.
Also calculate (a) N/No from equation 3.40 and compare this with the value obtained from Figure 3.34, (b) the remaining number of coliforms and the percentage reduction by UV radiation. The fraction remaining in a dispersed PFR is more than three times that of an ideal PFR.
Equalization of Flow and Mass Loadings
The volume of an equalization basin is fixed for (a) flow equalization and (b) mass load equalization. Determine the volume of an equalization basin to draw a constant flow of 652 m3/min to a biological sewage treatment plant. The basin flow diagram and the residual volume at any time of day are plotted in Figure 3.38.
Hourly flow and influent COD concentration data in the equalization basin are provided below. Plot the inflow and outflow flow profiles, and the inflow and outflow COD concentration profiles in the three equalization basin volumes. Prepare the calculation table to determine the constant flow and the theoretical volume of the basin (Table 3.13).
The inflow and constant flow profiles from the equalization basin with a theoretical volume of 0.133 ML are shown in Figure 3.39. If there is no flow accumulation in the basin, the inflow and outflow profiles are independent of the volume of the equalization basin.
Chapter Objectives
Relationship between Municipal Water Demand and Wastewater Flow
In filtration/inflow (I/I), the sewage can enter during wet weather conditions and can significantly increase the flow over a short period. Designers often assume that annual average wastewater flow is equal to 80–100% of the annual average water consumption in a community. The daily wastewater flow pattern measured at a wastewater treatment plant is similar to that of water demand, but exhibits less fluctuation and shows a delay of several hours.
The flow from different parts of the city takes different time to reach the central location (treatment plant or pumping station). A sample of the daily flow of municipal water demand and wastewater flow for a typical dry day is given in Figure 4.1. Calculate the following: (a) average daily water demand, (b) average daily wastewater flow, (c) ratio of average wastewater flow to water consumption, (d) ratio of peak to average wastewater flow, and (e) ratio between maximum and average water demand.
Components of Municipal Water Demand
With flow reduction devices, the residential water demand for many types of residential establishments decreases. The industrial water demand can be estimated based on proposed industrial zoning and unit loads for specific industries. Size, population density and economic conditions of the community: Wealthier and sparsely populated communities have a greater demand for water.
Commercial, industrial, institutional and public water use and lost or unaccounted for water account for 8% of total municipal water demand. ¼59% of total municipal water demand Residential water demand of municipal water demand Total municipal water demand ¼ 6300 m3=d dwellings. Residential, commercial, industrial, and institutional water needs and their percentages relative to total municipal water use.
Estimate the average water demand and the average water loss through cracks at a pressure of 414 kN/m2. EXAMPLE 4.6: WATER SAVING WITH A REDUCTION VALVE (PRV) The house has a PRV installed at the entry point into the house.
Wastewater Flow
Wastewater Flow Variation
Wet Weather Peak Current: Wet weather peak current occurs after or during precipitation and involves a significant amount of I/I. These flow rates are necessary for sizing (1) flow meters, (2) lower range chemical supplies, and (3) pumping equipment. The recorded flow data is a measure of the combined infiltration and daytime dry weather flow in the interceptor.
The daily average dry weather flow is calculated from the dry weather daily flow curve given in Figure 4.4.
Chapter Objectives
Physical Quality
A series of dilutions were made in odor-free water so that the total volume of the diluted sample was 200 ml in each case. Solids in municipal wastewater contain 50-80% volatiles and 20-50% solids, although this ratio can vary widely. The volatile solids in each category are determined by igniting dry solids in a muffle oven at 550+50◦C.
One liter of raw wastewater sample was settled in an Imhoff cone for 1 hour to determine the volume of settleable suspended solids (SS). Calculate (1) TSS, (2) non-settable (or non-filterable) SS, (3) settleable SS, (4) total dissolved (filterable) solids (TDS), and (5) the concentration of solids in the settled silt in the Imhofegel. Calculate the following: (a) the total volume of wet sludge, (b) the total amount of settleable solids in the sludge, (c) density and specific gravity of liquid sludge, and (d) the expected volumetric concentration in the courtyard cone.
Give the concentrations of volatile and solid suspended and dissolved solids in a typical municipal wastewater. A block diagram of the various components of suspended and dissolved solids in municipal wastewater is given in Figure 5.2.
Chemical Quality
Measurement of Organic Matter and Organic Strength
The remaining volume is filled with dilution water that contains the essential nutrients and is saturated with dissolved oxygen. The microbial oxidation of organic matter and BOD ratio is expressed by equations 5.2 to 5.4. BOD5 exerted by organic matter including biomass can be estimated from the biodegradable fraction of the organic matter.
A BOD5 of 120 mg/L means that microorganisms in aerobic conditions will consume 120 mg of oxygen in 5 days and at 20◦C to stabilize organic matter in 1 L of wastewater. A discussion of the solubility of oxygen and other gases can be found in Chapter 10 and Appendix B. What is the BOD test dilution water for and what does it contain.
The purpose of the dilution water in the BOD test is to dilute the wastewater sample in the BOD bottle. Thus, the use of dilution water (1) reduces sample volume in BOD bottles, (2) increases available dissolved oxygen, (3) provides necessary nutrients, and (4) provides a microbial population with the seed.