Introduction

Microorganisms Classification Figure

Biological wastewater treatment is often associated with secondary waste-water treatment and intends to treat the dissolved and colloidal organics after primary treatment. The goal of all biological wastewater treatment systems is to coagulate and remove or reduce the nonsettling organic solids and the dissolved organic load from the effluents by using micro-bial communities to degrade the organic load through biochemical reactions. Biological wastewater treatment is generally a major part of...

Sludge Quality and Characteristics

Sludge is rather complex material, both in the sense of its composition and in the characteristics of its fluid dynamics, which are shaped by its moisture content and interactions between water molecules and other solid particles. In general, when the moisture content of the sludge exceeds 90 by mass or weight, the sludge behaves as a Newtonian fluid, whereas below 90 it behaves as a non-Newtonian fluid in a way similar to those of some polymers (both certain biopolymers such as foods and...

Land Applications and Surface Disposal

Land application of sludge is defined as the beneficial use of the sludge at agronomic rates all other land displacements are considered as surface Figure 7.12. A schematic diagram of a rotary dryer for sludge dewatering. Figure 7.12. A schematic diagram of a rotary dryer for sludge dewatering. Figure 7.13. A schematic diagram of a multieffect evaporator for sludge de-watering. Figure 7.13. A schematic diagram of a multieffect evaporator for sludge de-watering. disposal of sludge. The detailed...

Material Balances and Stoichiometry

In dealing with food and agricultural wastewater, whether formulating treatment and utilization strategy or planning the initial stage of a comprehensive management project, a basic understanding of the effects of mass flow rate or loading factors on process designs is essential. Stoichiometry is the material accounting for a chemical reaction. Given enough information, one can use stoichiometry to calculate masses, moles, and percents within a chemical equation that is an expression of a...

Preface

This book was developed in response to the growing problem of food and agricultural wastewater management faced in both developing and developed countries as the world population continues to increase and, at the same time, industrialized food production has seen its most stunning growth in many nations from Argentina, to Brazil, to China. Currently, it is recognized that the increasing amount of the wastewater from these industrial scale processing plants can no longer be totally resolved by...

Recoverable Carbohydrates Fats and Proteins for Human and Animal Consumption

Currently, whey proteins are recovered from liquid whey for both human consumption and animal feed in limited quantities in the dairy industry. Whey proteins have found uses in infant formulae, in health foods, and in Table 8.2. Potential products from wastewaters generated from different food-processing sectors of the food industry. Offal, blood, soluble proteins, DAF sludge Spent brewer's yeast, starch, and waste grains Trimmings, fruit pomace, and flavors Beverage spills, wine grape...

References

Abou-Nemeh, I., Majumdar, S., Saraf, A., Sirkar, K.K., Vane, L.M., Alvarez, F.R., and Hitchens, L. 2001. Demonstration of pilot-scale pervaporation systems for volatile organic compound removal from a surfactant enhanced aquifer remediation fluid. II. Hollow fiber membrane modules. Environmental Progress, 20 64-73. Ahn, J., Daidou, T., Tsuneda, S., and Hirata, A. 2002. Characterization of denitrifying phosphate-accumulating organisms cultivated under different electron conditions using...

Nitrification

Nitrification is a microbial process that converts ammonia into nitrite and ultimately into nitrate. Ammonia in wastewater comes primarily from two sources intense use of nitrogen-rich fertilizers such as urea and organic nitrogen from proteins. The deamination of organic nitrogen and hydrolysis of urea under urease results in ammonia (Equations 2.6 and 2.7) Urea + 2H2O b (NH4 + )2CO32-Amino acid + 0.502 b R-CO-COOH + NH4 for oxidative deamination and Amino acid + 2H b R-CH2 -COOH + NH4 for...

Process Economics

Process economics is the next step of a wastewater treatment and management design project after preliminary selections of wastewater treatment processes have been completed in accordance with the project objectives. The economical considerations of the wastewater treatment and management project, including aspects of material and energy recovery, are among the most important factors that influence the final decision of the project. To develop meaningful cost estimates, the data from the...

Advanced Wastewater Treatment Processes

Biological treatment processes, in combination with primary sedimentation, typically remove 85 of the BOD5 and soluble solids originally present in the raw wastewater and some of the heavy metals. Activated sludge generally produces an effluent of slightly higher quality, in terms of these constituents, than trickling filters or RBCs. When coupled with a disinfection step, these processes can provide substantial but not complete removal of bacteria and virus. However, they remove very little...

Energy or Fuel Generation from Wastewaters

Ethanol is now being used in gasoline blends and fuel for specifically designed automobile engines. Ethanol can be produced from food and agricultural wastewaters as long as there are sufficient amounts of sugar or starch. The fermentation-produced ethanol has relatively low ethanol content, which has to be enriched to 95 or higher for use as fuels for internal combustion engines. A combination of distillation and pervaporation will produce an almost 100 pure ethanol (Peng et al., 2003). Biogas...

Conditioning of Sludge

The aim of sludge conditioning is improving dewatering characteristics of sludge. Dewaterabilities of sludges are varied some, such as activated sludge, are difficult to dewater. The difficulty in activated sludge dewater-ing is mainly attributed to the presence of extracellular polymer (ECP). ECP is present in varying quantities in sewage sludge, occurring as either a highly hydrated capsule surrounding the bacterial cell wall or loose in solution as slime polymers. ECP is thought to aid the...

Recoverable Food Agricultural ByProducts for Nonfood Uses

As shown in Table 8.2, specialty chemicals such as tartrate can be produced from wine grape wastes glue and gelatin can be extracted from Table 8.3. Abundant volatile flavor compounds in commonly blanched vegetables.* Table 8.3. Abundant volatile flavor compounds in commonly blanched vegetables.* *Data from MacLeod and MacLeod (1970), Maruyama (1970), Buttery et al. (1976), and Whitfield and Last (1991). *Data from MacLeod and MacLeod (1970), Maruyama (1970), Buttery et al. (1976), and...

Estimating Overall Costs of Wastewater Treatment Processes with Substance and Energy Recovery

Overall costs of wastewater treatment processes with substance energy recovery in a treatment facility are the sum of capital costs and operating costs minus sale price or savings of recovered substances and or energy. However, forecasting cost savings as a result of recovered substances and or energy is difficult. Whether a new product or energy from a waste-water treatment facility will be accepted in the marketplace depends on several factors, including additional costs of producing the...

Recoverable Aroma Flavoring Compounds from Food Processing Wastewaters

Recovery of flavors and savory compounds from food wastewaters has long been contemplated however, it was not economically and technically possible (with few exceptions) until the advent of membrane-based technologies. Today, pervaporation technology has been used successfully for recovering flavor products from fermentation broth in bioreactors and for aroma recovery (Trifunovic and Tragardh, 2002 Peng and Liu, 2003). Wastewaters from fruit and vegetable processing operations, in particular,...

Structures of Cells

Cell types include prokaryotes, which encompass all bacteria, and eukary-otes, which are cells in all living cells except bacteria and viruses. Bacterial cells are molecules surrounded by a semipermeable membrane and which in turn is covered by a porous cell wall. The protoplasm in the membrane contains nuclear material that is not bounded by any other material separating it from the protoplasm. Organelles are complex and well-defined internal structures surrounded by membranes. Characteristic...

Filtration Processes

Filtration is often employed in wastewater treatment, with or without prior treatments by coagulation-flocculation and sedimentation, for removal of flocs (or bioflocs) from primary and secondary wastewater treatment processes, solids remaining in effluents from primary and secondary wastewater treatment processes, and precipitates from physicochemical treatment of phosphate from the advanced wastewater treatment stage. Earlier applications of filtration for wastewater treatment borrowed...

Adsorption

Adsorption is a physicochemical process that generally occurs at the interface of fluid-solid phases and is sometimes used to remove certain species that cannot effectively be removed from the wastewater stream by other conventional technologies. Although it is quite possible that liquid-liquid or gas-liquid interaction results in adsorption, it is more common in waste-water treatment to observe interactions of two fluid phases as absorption. Adsorption and absorption, which belong to the same...

Reed Beds

Reed beds constructed in wetlands provide long-term storage and volume reduction of sludges (sludge stabilization and dewatering) to mitigate environmental concerns. Widely used throughout Europe, Asia, and Aus- Table 7.3. Design considerations for aerobic sludge composting (adapted from Metcalf and Eddy, Inc., 1991). Table 7.3. Design considerations for aerobic sludge composting (adapted from Metcalf and Eddy, Inc., 1991). Wood chips, sawdust, recycled compost, and > 50 remaining in all...

Sludge Stabilization

Once the sludge is thickened, two options are available for further treatment of the concentrated sludge. It can be dewatered to a solid content of between 30-40 or it can undergo stabilization processes to reduce the organic materials in the sludge before going to the dewatering step. Coarse primary solids and secondary sludge (sometimes called biosolids) accumulated in a wastewater treatment process must be treated before disposal to ensure environmentally responsible and lawful outcome....

Coagulation and Flocculation

Many substances in wastewater vary greatly in size, from a few angstroms for soluble solids to a few hundred microns of suspended materials. Consider a force balance upon a clay particle with diameter of 1 micron in the absence of electrostatic forces, the terminal settling velocity of this particle in water is approximately 10 4 cm s based on the following expression (Equation 3.6) where (ps pf) is the density difference between the particle and fluid (water), and is the viscosity of the fluid...

Wetland Systems

Natural wetlands (e.g., swamps, bogs, marshes, fens, sloughs, etc.) are long recognized as providing many benefits, including food and habitat for wildlife, water quality improvement, flood protection, shoreline erosion control, and opportunities for recreation and aesthetic appreciation. Many of these same benefits have been realized by projects across the country, which involve the use of wetlands in wastewater treatment. Wetlands are constructed as either surface flow (see Fig. 6.10) or...

Physicochemical Removal of Phosphate

There are several physicochemical phosphate removal processes that can be used with conventional secondary wastewater treatment. These processes generally involve using chemicals to facilitate precipitation of phosphate and a primary clarifier (sedimentation tank or basin) to separate phosphate-containing sludge from the treated wastewater or in some cases, dissolved air flotation is used to remove the phosphorus-containing complexes. The principal chemicals employed in this type of removal are...

Kinetics and Reaction Rates

Chemical or biochemical kinetics is the study of chemical or biochemical reactions with respect to reaction rates, effect of conditions reactions are subject to, rearrangement of molecules, formation of intermediates, and involvement of catalyst. The word kinetics is originated from the Greek kinesis, meaning movement. Thus, the kinetics of chemical or biochemical reactions are mainly concerned with rate of reaction and anything else affecting it. In general, the reaction rate depends on the...

Floating Aquatic Plant Systems

Benefits Duckweed Root

Aquatic plant systems are engineered and constructed systems that use aquatic plants in the treatment of industrial or domestic wastewater. They are designed to achieve a specific wastewater treatment goal. Aquatic plant systems can be divided into two categories Systems with floating aquatic plants such as water hyacinth, duckweed, Systems with submerged aquatic plants such as waterweed, water milfoil, and watercress The use of aquaculture as a means of treating wastewater involves both...

Physicochemical Removal of Nitrogen

As described previously, biological nitrogen removal is not the only technology available for nitrogen compound removal from wastewaters. Some nonbiological processes are able to recover nitrogen compounds in their dissolved forms for potential uses as fertilizers and are viable alternatives under some circumstances. On the whole, however, physicochemical processes for removing nitrogen from wastewater are not practically popular. The reasons for the unpopularity are often cited as cost,...

Sedimentation

Sedimentation is the most common physical unit operation in wastewater treatment, more so in primary treatment where sedimentation is the workhorse of the treatment. The term sedimentation is also called settling in some literature. Sedimentation is, in a nutshell, a process by which the suspended solids, which have higher densities than that of water, are re- Figure 3.5. A photo of a dissolved air flotation system. Figure 3.5. A photo of a dissolved air flotation system. moved from wastewater...

Stabilization Ponds

Facultative Ponds

One of the ancient wastewater treatment technologies, the stabilization pond (also referred to as a lagoon), has been used continuously as a method of sewage disposal. In some cases, these ponds were also utilized for aquaculture. Stabilization ponds are used for both municipal waste-water treatment and industrial wastewater treatment, particularly for wastewaters from small communities and seasonal industrial wastewaters as well as less affluent communities throughout the world (Fig. 6.1)....

Rotating Biological Contactor RBC

Rotating Biological Contactors (RBCs) are used in the treatment of wastewater as a secondary treatment process. The RBC process involves allowing wastewater to come in contact with a biological medium in order to remove contaminants in sewage before discharge of the treated wastewater to the environment, usually a river. The construction of an RBC consists of a series of plastic discs, the media, mounted on a driven shaft that is contained in a tank or trough. Commonly used plastics for the...

K k1 r k

The k's appearing in the equation are mass transfer coefficients, and their reciprocals represent the mass transfer resistance at each step. For many pervaporation processes, the mass transfer resistance in the vapor boundary layer tends to be small enough to be ignored. This leaves only the liquid boundary layer (1 bl) and membrane (1 km) resistances to deal with. km is strongly determined by polymer properties, the thickness of the membrane, and chemical structures of the components in the...

Screening

Screening Wastewater Treatment

Wastewater from food processing or postharvest processing may contain debris, either suspended or floating on the surface. These coarse solids have to be removed at the very beginning of the wastewater treatment regimen. Screening of debris is sometimes considered as a preliminary treatment, Figure 3.3. A photo of an inclined screen. Figure 3.3. A photo of an inclined screen. not part of primary treatment of wastewater however, the distinction is more semantics than anything else. Screening can...

Ion Exchange

Ion exchange is a process in which ions of a particular species in solution are replaced by ions with a similar charge but of different species attached to an insoluble resin. In essence, ion exchange is a sorption process and can also be considered a reversible chemical reaction. The common appli cations of ion exchange are water softening (removal of hardness ions such as CA2+ and Mg2+) and nitrate removal in advanced wastewater treatment operations. These ion exchange resins are either...

Important Microorganisms in Wastewater Bacteria and fungi

Bacteria are the most important and the largest components of the microbial community in all biological wastewater treatment processes. Depending on the biological process and pH, the number concentration of bacteria is different, with activated sludge (aggregates of healthy aerobic bacteria living in colonial structures called flocs) having the largest number concentration of bacteria. Bacteria range in size from approximately 0.5 to 5 m and take one of four major shapes sphere (cocci),...

Biological Removal of Phosphorus

Biological Remediation Processes

Phosphorus is a constituent of wastewater, averaging around 10 mg liter in most cases. The principal form in food and agricultural wastewater is organically bound phosphorus. Organically bound phosphorus originates from body and food waste and, upon biological decomposition of these solids, is converted to orthophosphates. Biological phosphate removal is a relatively new technology dating back to the late 1950s it wasn't until the 1970s that there were full-scale processes developed for...

Combined Aerobic Processes

Fluidized Bed Reactor

The combined aerobic processes are designed to sustain shock loads in activated sludge, aerobic contactor, and trickling filter (biofilter) processes. There are several possible combinations of these aerobic processes activated biofilter process, trickling filter solids-contact process, biofilter activated-sludge process, and trickling filter-activated sludge process. The activated biofilter process is a trickling filter with recycling of secondary sludge back to the trickling-filter to create...

Sludge Thickening Concentration

Thickener Diagram

Further sludge concentration is first accomplished by the use of thickening equipment that will increase the solids content to between 2 and 5 . Sludge thickening is achieved through one of two means flotation and settling to the bottom by gravity or centrifugal force. The thickening operation separates water from the sludge as much as possible and is cost-effective because the cost involved in the process is well offset by the savings gained through the reduction of sludge volume, which...

Belt press filtration

Fresnel Lens Used For Drying Water

Belt filter presses employ single or double moving belts to continuously dewater sludges through one or more stages of dewatering. All belt press filtration processes include three basic operational stages chemical conditioning of the feed sludge gravity drainage to a nonfluid consistency shear and compression dewatering of the drained sludge. When dewater- Figure 7.5. A schematic diagram of a belt filter for sludge dewatering. (Courtesy of Falke Bruinsma at http photos.innersource.com) Figure...

Biological Removal of Nitrogen Nitrification and Denitrification

The goal of nitrogen removal, regardless of what exactly forms of nitrogen compounds in wastewater streams, has been the production of nitrogen gas, an inert, water-insoluble gas that is easily separated from liquid media. The necessity of producing nitrogen gas in the treatment processes of nitrogen removal is mainly due to high solubility of nitrogen compounds such as NO3 , NH4+, and NO2 present in the nitrogen removal. There is some indication that this old paradigm is being challenged....

Estimating the Unit Cost of Treating Food and Agricultural Wastewater

Cost estimation of a yet-to-be-built wastewater treatment facility is difficult as an engineer or process designer, your responsibility is not to try to outsmart the experts that are hired to do cost forecasting if a decision of building a specific design of wastewater treatment facility is finalized rather, your job is to estimate the total costs of a particular wastewater project in order to compare the one under the study to other treatment management alternatives or options. The estimation...

Membrane Processes for Advanced Wastewater Treatment

Wastewater Treatment Membrane

An overview about membrane processes that can be used in wastewater treatment has been presented in Chapter 3 the general characteristics of various processes determine the applications of membrane processes in wastewater treatment. Membrane filtration can theoretically replace conventional processes such as secondary sedimentation, flocculation, settling basin, and granular filtration all together. In reality, however, the applications of membrane filtration in wastewater treatment are...

Land Treatment Systems

Waste Water Infiltration System Canada

Land application of wastewater is perhaps the oldest method for disposal and treatment of wastewaters. Early systems were used in England as Land Farms, which received untreated wastewater and night soil from nearby communities. Today, land application systems have included application to edible and nonedible crops, to rangelands, to forests and wood plantations, to recreational areas including parks and golf courses, and to disturbed lands such as mine spoil sites. Land application of...

Characteristics of Agricultural and Food Wastewater

Biological Oxygen Demand Test Flowcharts

Whenever and wherever food, in any form, is handled, processed, packed and stored, there will always be an unavoidable generation of wastewater. Wastewater is the most serious environmental problem in the manufacturing and processing of foods. Most of the volume of wastewater comes from cleaning operations at almost every stage of food processing and transportation operations. The quantity and general quality (i.e., pollutant strength, nature of constituents) of this processing wastewater...