minimization of environmental impact of sludge …...minimization of environmental impact of sludge...

Minimization of Environmental Impact of Sludge through Optimization of the Processing Methods

BALA ABARSHI

Department of Civil Engineering Morgan State University

1700 E. Cold Spring Lane, Baltimore, Maryland 21251, USA [email protected]

MONTIER KESS

Department of Industrial and Systems Engineering Morgan State University


SEYEDEHSAN DADVAR

Department of Transportation and Urban Infrastructure Studies Morgan State University


GBEKELOLUWA OGUNTIMEIN

Department of Civil Engineering Morgan State University


Abstract: - Sludge is defined by the scientific community as the residual semi-solid material from industrial processes, sewage treatment and agricultural run-off. Sludge is non-homogeneous as it consists of heavy metals, varying levels of organic material such as animal waste by-products, along with various minerals. There are different methods to treat and dispose the sludge. The selection of the correct treatment method for sludge will be effective if certain factors are put into consideration. The relative sludge process ability, sludge mass, environmental risk assessment of sludge, analysis and design of sludge treatment plants will be discussed in this paper. A closer study of the different forms of treatments and disposal will be outlined, such a conceptual usage of one of OR methods will be presented to help decision-makers to select the best alternative among others, then reliability of systems will be assessed and an application of ASIM software will be provided to simulate a possible sludge treatment plant with the data of Baltimore City, at last a conclusion will be reached. The results indicated the possible opportunities to treat about 42% of sewage sludge in Maryland which currently hauling out of State. Key-Words: - Sludge, Sewage, Treatment, Disposal, Simulation, Optimization, OR, ASIM software 1 Introduction Sludge is defined by the scientific community as the residual semi-solid material from industrial processes, sewage treatment and agricultural run-off. Sludge is non-homogeneous as it consists of heavy metals, varying levels of organic material such as animal waste by-products, along with

various minerals. Industrial plants often use high volumes of water in their operations such as cooling metal and diluting acids. During these processes the water used often becomes contaminated by a number of high toxic chemicals and heavy metals. Likewise all urbanized areas with modern plumbing generate sludge from animal and human waste management. Sludge also contains an incredibly

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rich source of bacteria, which feed off the organic material found in the sludge. This wastewater then joins with other byproducts to form a substance known as sludge. The solids found in sludge are suspended in the medium and will eventually settle given enough time. Raw sludge as a by-product of various functions has historically been dumped or shipped to landfills for disposal. In 1980s with the passage of the several environmental laws, sludge disposal by this practice has decreased. Since that time the agencies responsible for sludge disposal has found other forms of use and disposal method for sludge. The history of sludge treatment dates back in New York City as early as 1924. The treatment plant began dumping its sewage sludge twelve miles outside of New York Harbor. Several decades later the Environmental Protection Agency deemed coastal water dumping as unacceptable and suggested that sludge be dumped at least 106 miles offshore. Some of the items included in the sludge were medical debris and hypodermic needles from local hospitals [37]. In the early part of 1970s, the National Environmental Policy Act was enforced. This policy was created to promote the enhancement of the environment and was used to set up procedural requirements for federal agencies preparing environmental assessments (EA) and environmental impact statements (EIS). Each year more than 700,000 wet tons of sewage sludge is generated in Maryland alone. Maryland Department of the Environment (MDE) statistically has shown that (1) 30% of sewage sludge is applied to agricultural land, (2) 13% is composted or pelletized and made into a commercial soil supplement, (3) 3% is used for land reclamation such as restoring surface mines, (4) 42% is hauled out of state, and (5) 12% is disposed in landfills or incinerated [8]. There is a lack of readily available economically sensible and efficient system designs that offer alternative ways for treatment and disposal of sewage sludge. 1.1 Environmental Risk Assessment of Sludge The process of handling the sludge is tightly regulated by the local, state and federal environmental protection agencies in accordance with numerous laws including but not limited to the Clean Water and Clean Air Acts. The reason for this regulation is because accidental or deliberate release

of this material can cause severe damage to the environment and population concentrations. In rural areas, the sludge generated normally consists of animal waste and by-products, plant material, plastic, glass, household chemicals and a small percentage of industrial chemicals and substances. This make up of sludge will not cause long term damage to the environment due to the absence of high concentrations toxic materials or heavy metals. However the major risk with this type of release is the possibility of sludge being released in the local food and water supply. Rural areas produce the majority of food for the country and any spill or contamination in these areas can prove challenging to isolate and disposal of affected food. Another risk of sludge spillage in rural areas is the lack of proper infrastructure to deal with spillage or accidents. Unlike urban areas with high population density, rural areas do not have on-call agencies and field agents who can readily respond to spillage or accidents involving sludge. As a result, a greater quantity of hazardous material could be released before the proper authorities can respond. In urban areas, sludge typically has higher percentages of heavy metals and toxic substances. This is due to industrial factories and its associated technology. Heavy metals such as cadmium are used in industrial facilities and as a result of breakdown, normal operation, or maintenance, this element along with other toxic materials is released into municipal water treatment process. Sludge from urban areas is also greater in volume due to the increased population density and governments have developed treatment facilities away from residential areas to process and dispose of the wastewater and residual sludge. These complex sites are designed to receive, process, and contain sludge. The designs of the sites vary according to budget and requirements, however they are all inspected and reported to EPA and state and local environmental agencies. The risk of spillage of sludge at these sites is low due to the fact that the containers are designed with multiple safeguards to prevent such a release. In addition standard operating procedures are often automated to reduce the risk of human error. Water treatment facilities in urban areas often release the treated water into the local waterway. While the composition of the water is regulated, the released water is not 100% pure and does contain some contaminants. A consequence of this is that the local wildlife within five miles of a water treatment area often exhibits some form of biological defect from this water. Additionally,


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many rivers downstream of wastewater processing plants are declared unsafe from fishing or swimming due to the risk of accidental exposure to toxic materials. 1.2 Different Types of Treatment and Stabilization Processes Sewage sludge treatment is usually classified in two groups: (1) Aerobic and (2) Anaerobic. Aerobic digestion is a bacterial process occurring in the presence of oxygen. Under aerobic conditions, bacteria rapidly consume organic matter and convert it into carbon dioxide. Once there is a lack of organic matter, bacteria dies and is used as food by other bacteria. Because the aerobic digestion occurs much faster than anaerobic digestion, the capital costs of aerobic digestion are lower. However, the operating costs are characteristically much greater for aerobic digestion because of energy costs for aeration needed to add oxygen to the process. Anaerobic digestion is a bacterial process that is carried out in the absence of oxygen. The process can either be thermo-philic digestion in which sludge is fermented in tanks at a temperature of 55°C or meso-philic, at a temperature of around 36°C. Though allowing shorter retention time, thus smaller tanks, thermo-philic digestion is more expensive in terms of energy consumption for heating the sludge. Before being disposed, sewage sludge must be stabilized and disinfected to reduce pathogens, the attraction of vectors (disease transmitting organisms like flies and rodents), and the potential to emit odors. The same is true for landfilling unless the sewage sludge in the landfill is covered daily. During stabilization and disinfection, pathogens are either significantly reduced (Class B) or reduced below detectable levels (Class A). Class A treatment methods can be compared with pasteurization of milk or cooking of foods, where high temperatures significantly reduce or kill pathogens in order to prevent the risk of disease transmission. Class B stabilization methods reduce pathogens to higher levels than Class A stabilization, so site and crop restrictions are still necessary. Site and crop restrictions for Class B sewage sludge keep potential pathogens from human contact until environmental conditions, like sunlight, lower the pathogen density in the sludge so that pathogens are no longer a risk. Some of the stabilization methods include anaerobic digestion, aerobic digestion, lime stabilization, composting, advanced alkaline stabilization, and heat drying.

Anaerobic Digestion, Aerobic Digestion, Lime Stabilization Anaerobic digestion, aerobic digestion, and lime stabilization are the most common methods of sewage sludge stabilization. Lime stabilization is a simple and inexpensive chemical method. Lime is added to the sewage sludge to raise the pH of the sewage sludge to twelve after two hours of contact. A benefit of anaerobic digestion is the generation of methane, which can be used as an energy source. Anaerobic digestion is only economical for larger communities due to the high capital costs involved. Aerobic digestion, an energy-intensive process, is typically found at smaller Publicly Owned Treatment Works (POTWs). However, all three methods-anaerobic digestion, aerobic digestion, and lime stabilization-produce in most cases are only Class B sewage sludge. Since the use of Class B sewage sludge is more stringently regulated than Class A sewage sludge, there is an increasing interest in Class A stabilization methods, such as composting, alkaline stabilization, and heat drying. Projects for composting sewage sludge, or co-composting with municipal solid waste (MSW), or yard waste, have increased in recent years. Composting is used mostly by communities that produce low volumes of sewage sludge, and is often limited by the lack of long-term markets for the finished compost. Composting can be expensive and uncontrolled odors can expose sites to potential nuisance liability. Advanced alkaline stabilization neutralizes harmful pathogens in the sewage sludge by adding liming agents to increase PH above twelve for a minimal of seventy-two hours, with temperatures held above fifty-two degrees Celsius for at least twelve hours during this period. Quick lime, hydrated lime, or cement kiln dust are added to solidify the material, and the product has been used as a liming agent in agriculture or as daily cover and capping material at Municipal Solid Waste (MSW) landfills. Another stabilization technique is heat drying. The heat drying technology can be used for sewage sludge stabilization in two ways. In the first method, dryers are sometimes used after dewatering sewage sludge in presses or centrifuges, as a single process to reduce the weight and volume of the sludge so that it may be transported for disposal. In the second method, heat drying is also used as part of a process to create a usable end product that flows easily and can be used in fertilizer mixes. This pelletizing process uses heat to dry the sewage sludge between ninety and ninety-five percent solids, thus reducing


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volume and killing pathogens before the sewage sludge is turned into pellets and sold as fertilizer. This method is one of aerobic methods. The term 'activated sludge' refers to sludge in the aeration tank of an activated sludge treatment process. It consists of flocks of bacteria, which consume the

biodegradable organic substances in the wastewater. Because of its usefulness in removing organic substances from wastewater, the sludge is kept in the process by separating it from the treated wastewater and re-circulating it.

Fig.1 Conventional Activated Sludge Process [36] The capital cost for building such a plant is relatively high. The energy requirement, particularly for providing air to the aeration tank, is also relatively high. There is a need for regular maintenance of the mechanical equipment, which requires skilled technical personnel and suitable spare parts. The operation and maintenance costs of an activated sludge treatment plant are therefore relatively high. An activated sludge treatment process can be operated in batches rather than continuously. One tank is allowed to fill with wastewater. It is then aerated to satisfy the oxygen demand of the wastewater, following which the activated sludge is allowed to settle. The treated wastewater is then decanted, and the tank is filled with a new batch of wastewater. At least two tanks are needed for the batch mode of operation, constituting what is called a ‘sequential batch reactor (SBR)’. SBRs are normally suited to smaller flows, because the volume of wastewater produced during the treatment period in the other tank determines the size of each tank. 1.3 Different Types of Disposal Methods The disposal options for this waste byproduct of modern sewage treatment methods are continuing to narrow, albeit at a slower pace due to the increased number of land application sites and mega-landfills. There are three main disposal alternatives for

sewage sludge: (1) landfilling; (2) incineration; and (3) land application. In 1995, about twenty-five percent of sewage sludge in the United States was landfilled by co-disposal with MSW, by disposal in sludge mono-fills, or by use as landfill cover in MSW landfills. In a few states, this amount was much higher (e.g., Nevada-75%; New Mexico-73%; Rhode Island-60%; Louisiana-45%). Based on the tighter supply of landfill space and greater recognition of the beneficial properties of sewage sludge, a few states, including New Jersey, enacted legislation banning or limiting the amount of sewage sludge that could be disposed of in landfills. Currently, however, because of the increase in the number of so-called mega-landfills, landfill space is abundant. So for some communities, the landfilling of sewage sludge is the least expensive alternative. About 16 percent of municipal sewage sludge is combusted in the United States. The most prominent advantage of this disposal method is the destruction of organic pollutants and the reduction in total volume of sewage sludge. The volume reduction can translate into reduced transportation costs. However, rising facility capital will most likely offset these cost reductions and operating costs driven by public concern over air emissions and ash residue disposal, coupled with tightening federal regulation of particulate emissions.


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Land application can be defined as the use of sewage sludge or sludge-derived products, like compost, alkaline stabilized materials, and pellets, on agricultural land, nonagricultural land (forests, reclamation sites, parks, etc.), and in home gardens. For use in home gardens, composts or pellets are distributed and marketed in bags or containers. EPA has increased its emphasis on land application of sewage sludge as a beneficial use because this option closes the natural nutrient cycle; moreover, land application is often the cheapest disposal option. Land application represents the most common method of sludge management in the United States. Micronutrients required by plants to remain healthy, such as zinc, chromium, iron, and copper, are usually not found in significant quantities in commercial fertilizers. Sewage sludge,

or sewage sludge-derived products, can be used as sources of micronutrients, liming materials, or as soil amendments. If sewage sludge is improperly handled, pollutants (trace elements or persistent organic chemicals) and pathogens (viruses, bacteria, or parasites) in sewage sludge could potentially contaminate soils, crops, livestock, and even humans. For example, successive sewage sludge applications to land can result in an accumulation of heavy metals in the soil. This accumulation can potentially result in soil concentrations of metals that are toxic to plants, soil organisms, animals, and humans along the food chain. In a report assessing the risks of sewage sludge land application, EPA identified fourteen potential exposure pathways resulting from such land application.

Table 1 Potential Exposure Pathways [28] Potential Exposure Pathways Potential Exposure Pathways Sewage Sludge > Soil > Plant > Human (Consumer of Plant Products) Sewage Sludge > Soil > Plant

Sewage Sludge > Soil > Plant > Human (Home Gardener) Sewage Sludge > Soil > Soil Organism

Sewage Sludge > Human (Child Eating Sewage Sludge)

Sewage Sludge > Soil > Soil Organism > Soil Organism Predator

Sewage Sludge > Soil > Plant > Animal > Human Sewage Sludge > Soil > Airborne Dust > Human Sewage sludge > Soil > Animal > Human (Animals ingest sludge directly) Sewage Sludge > Soil > Surface Water > Human

Sewage Sludge > Soil > Plant > Animal Sewage Sludge > Soil > Air > Human Sewage Sludge > Soil > Animal Sewage Sludge > Soil > Ground Water > Human 2 ASIM Tool Used for Analyzing Sludge Treatment There are several software tools that can be used for sludge treatment, however the ASIM tool was selected to analyze sludge and build a conceptual model of sludge disposal. ASIM stands for Activated Sludge Simulation Program and is a simulation program, which allows for the simulation of a variety of different biological wastewater treatment systems: Activated sludge systems with up to 10 different reactors in series (aerobic, anoxic, and anaerobic), including sludge return and internal recirculation streams, batch reactors, Chemostat reactors, etc. The program allows for the definition of process control loops, and dynamic simulation of load variation. Data analysis is supported by the possibility to compare observed data with simulation results in easy to use graphic support routines. Simulated results may be exported to spreadsheets for further treatment.

3 Design – Mutually Exclusive Al ternatives The following alternatives considered for ‘Mutually Exclusive Design Development Enhancement Alternatives’: Methods:

1. Thickening (THCK) 2. Stabilization (STAB) 3. Composting (COMP) 4. Dewatering (DEWT)

Purposes: 1. Green Design (G) 2. Agriculture (A) 3. Land Fill (L)

The following tables show the high level and lower level matrices. The last table summarized the final result and selected alternative.


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Table 2 High Level Matrix

THCK STAB COMP DEWT NTH ROOT PRODUCT

NORMALIZED NTH RT PRD M*N M*N/NORM

THCK 1.00 0.56 0.87 0.38 0.6566 0.1525 0.6101 4.0000 STAB 1.80 1.00 1.59 0.70 1.1891 0.2762 1.1050 4.0000 COMP 1.14 0.63 1.00 0.44 0.7493 0.1741 0.6963 4.0000 DEWT 2.61 1.43 2.28 1.00 1.7095 0.3971 1.5886 4.0000

SUM= 4.3044 1.0000 LamMax= 4.0000

CI= 0.0000

CR= 0.0000 Table 3 Low Level Matrix for thickening

G A L NTH ROOT

PRODUCT NORMALIZED NTH RT PRD M*N M*N/NORM

G 1.00 1.67 1.05 1.2051 0.3977 1.2266 3.0842 A 0.60 1.00 1.50 0.9655 0.3186 0.9827 3.0842 L 0.95 0.67 1.00 0.8595 0.2837 0.8748 3.0842

SUM= 3.0300 1.0000 LamMax= 3.0842 CI= 0.0421 CR= 0.0726

Table 4 Low Level Matrix for Stabilization

G A L NTH ROOT PRODUCT


G 1.00 0.83 2.50 1.2772 0.4019 1.2169 3.0279 A 1.20 1.00 1.82 1.2970 0.4081 1.2358 3.0279 L 0.40 0.55 1.00 0.6037 0.1900 0.5752 3.0279

SUM= 3.1779 1.0000 LAMMAX= 3.0279

CI= 0.0140

CR= 0.0241 Table 5 Low Level Matrix for Composition



G 1.00 0.25 0.33 0.4368 0.1255 0.3766 3.0012 A 4.00 1.00 1.20 1.6869 0.4846 1.4544 3.0012 L 3.00 0.83 1.00 1.3572 0.3899 1.1702 3.0012

SUM= 3.4809 1.0000 LAMMAX= 3.0012

CI= 0.0006

CR= 0.0011


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Table 6 Low Level Matrix for Dewatering



G 1.00 2.00 0.90 1.2164 0.3999 1.2317 3.0803 A 0.50 1.00 1.05 0.8067 0.2652 0.8168 3.0803 L 1.11 0.95 1.00 1.0190 0.3350 1.0318 3.0803

SUM= 3.0422 1.0000 LAMMAX= 3.0803 CI= 0.0401 CR= 0.0692

Table 7 Evaluation for all levels

THCK STAB COMP DEWT

Final Score 0.1525 0.2762 0.1741 0.3971

G 0.3977 0.4019 0.1255 0.3999 0.3523 A 0.3186 0.4081 0.4846 0.2652 0.3510 L 0.2837 0.1900 0.3899 0.3350 0.2966 The four types of treatment will be used, (1) Thickening, (2) Stabilization, (3) Composting, and (4) Dewatering, to rate how these alternatives correspond to three potential systems that include (1) Green Design, (2) Agriculture, and (3) Land Fill. In the high level matrix, values are conceptualized to show that ultimately there is no bias in the system for measuring the four alternatives against the three potential system designs. The important elements to understand in this model are the CI and CR values. The CI value is calculated by subtracting the N value of alternatives from the LamMax value, and then divided by (N-1). In the high level matrix, the value is 0. The CR value is calculated by dividing the CI value by an RI value, which is given as 0.9 for four alternatives. This value is 0 as well. This information tells us that our conceptualized data is 100% consistent and 0% biased. In the lower level matrices, we go into each alternative to measure it against itself to find out the biasness that occurs for that particular system design. As with the higher level matrix, the important values to consider here are the CI and CR values. For the Thickening Alternative measured against the three system designs, there is 92.74% consistency and 7.26% biasness. The object of this methodology is to have no more than 10% biasness. For Stabilization, we have 97.59% consistency and 2.41% biasness. For Composting, we have 99.89% consistency and 0.11% biasness. For Dewatering, we have 93.08% consistency, and 6.92% biasness. Ultimately, these numbers are conceptually configured to understand

our evaluation of the most optimal system design using one of the four alternatives within the system. Our evaluation system tells us that Dewatering has the higher percentage at 39.71% compared to the other three alternatives at 15.25%, 27.62% and 17.41% respectively. Our best system design is measured using information against the high level matrix. This is done by the following equation: First, take the G value from each table to include in the evaluation table from the normalization column, and take the alternative normalized values from the high level matrix. For green design, our equation reads: (0.3977 * 0.1525) + (0.4019 * 0.2762) + (0.1255 * 0.1741) + (0.3999 * 0.3971) = 0.3523. At 35.23% we know that a green system design that includes a dewatering process will be our first thought for creating our system design to treat and dispose sewage sludge. 4 Case Study – Maryland As a case study, state of Maryland has been selected for further analysis. 4.1 Sewage Sludge Management in Maryland Sewage sludge, also known as biosolids, is not raw sewage—it is actually one of the final products resulting from the treatment of sewage at a wastewater treatment plant where organic matter is broken down and disease-causing organisms are killed. After treatment, the remaining fine particles


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and water have a mud-like appearance and are classified as sewage sludge. Sewage sludge can also be solidified into a more earthlike material called “cake”. MDE’s Waste Management Administration, which oversees the proper utilization of sewage sludge in Maryland, established and enforces the sewage sludge regulatory requirements to protect human health and the environment. There are five major ways that sewage sludge, produced in Maryland, is managed. It is [1]: (1) Applied to agricultural land; (2) Composted or pelletized and made into a commercial soil supplement; (3) Used for land reclamation such as restoring surface mines; (4) Disposed in landfills; or (5) Used as combustion for energy. Sewage sludge, available free to farmers, is an excellent fertilizer and soil amendment because it contains nutrients that are beneficial to crops and because the nutrients gradually release over time. This is important because nutrients stay in the soil and on the field, rather than quickly dissolving and running off into streams, as can happen with chemical fertilizers and manure that are rich in ammonia. By applying sewage sludge on farmland, nutrients are recycled into living plants reducing nutrient pollution to the Chesapeake Bay. 4.2 Using ASIM Software to Develop a Sludge Treatment Process for Baltimore City, Maryland ASIM (version 4) was selected and used to simulate a sludge treatment plant for Baltimore City in Maryland. The main reasons were: (1) ASIM is software for modeling/simulating activated sludge processes; and (2) Variety of systems can be modeled. Based on the ASIM English tutorial, the main steps to model a system are project creation, model creation, plant definition and details, variation definition (for dynamic simulation), computation, and results [1].

The project team limited the simulation study to Baltimore City due to familiarity of the environment and resources because our conceptualized design can provide actual results if used by a government agency or private-sector company. Based on the facts, each year more than 700,000 tons of sewage sludge is generated in Maryland and 42 percent is hauled out-of-State (294,000 tons equal to 832,520 m3). We assume there may be a correlation between the amount of sewage sludge and population. Based on the population of Baltimore City, which is 16 percent of Maryland, Baltimore City’s portion in generating sewage sludge for each year will be approximately 133,210 m3 (365 m3/day). 4.2.1 Project Creation For creating a model, the user can select from ASIM pre-defined models or create their own model. For this project we used one of the pre-defined models available in the ASIM Software catalog (ASM3_swiss). The selected model is more developed in comparison with the original model and includes more treatment processes. The user can modify basic information in the “Model Description and Definition” window. 4.2.2 Plant Definition and Details After model selection, the user should define the plant details. The critical features for design are as following [1]:

• Number of reactors • Return sludge flow rate (per day) • Saturation concentration for Oxygen • Number of secondary clarifiers • Internal recirculation flow rate (per day) • Operating temperature • Influent flow rate (per day) • Sludge age (day) • Details for reactors and secondary clarifiers

For the purpose of this study, data of Table 9 has been used.

Table 1. Plant Definition Based on the Baltimore City Features for Sewage Sludge Item Amount Influent (m3/day) 365 Volume of tanks (m3) 2000 Volume of secondary clarifier (m3) 750 Return sludge (m3/day) 100 Sludge age (day) 7 Saturation of concentration of Oxygen (mg/L) Default Base temperature (Centigrade) 15.2 Operating temperature (centigrade) 20


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4.2.3 Variation Definition A Variation File contains information that is necessary for dynamic simulations, such as changes in influent, excess sludge draw-off (DX), and concentrations over a certain stretch of time. For this project, we only provided temperature variation for 24 hours based on Baltimore City’s average yearly temperature.

4.2.4 Results Fig.2 and Fig.3 are aerobic storage of all reactors and reactors rates O2 of all reactors. These are only selected results are creating by ASIM. It should be noted that because of using student version of the software there is a “Demo” watermark on the results.

Fig.2 Aerobic Storage of All Reactors

Fig.3 Reactors Rates O2 of All Reactors


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The ability of this software to provide an online simulation of the plant and different reactors proved well based on the results (graphs) among so many other useful results. Using the results will let the users, designers, decision makers, and analysts to check the performance of the all reactors and all plants and

compare the statistics with the standards and also compare different combination of reactors (size, function and number). Final design of the sewage sludge treatment plant based on the selected case study (Baltimore City) and amount of hauled-out-of-state, demonstrated in Fig.4.

Fig.4 Final Design of Sludge Treatment Plant for Baltimore City 5 Conclusion and Discussion Based on the process and results, the ASIM tool can be used for simulating and analyzing different plants. Some suggestions to improve the results:

• Providing full version of ASIM software or other similar software packages to simulate and develop treatment plants- more options and graphs will be available to analyze and compare to real designs currently used.

• Considering more details for Baltimore City including other components of dynamic simulation which may increase the accuracy of the models.

• Calibrating the used model in this project for Baltimore City and later for entire state of Maryland.

• Creating Baltimore City’s model in ASIM based on local conditions.

The overall goal of this effort was to cut down the sludge hauled out of Baltimore city due to insufficient infrastructure, using the treated sludge as green alternatives (waste to energy, agriculture).

Modern waste-to-energy facilities are reliable and environmentally safe ways to dispose of large amounts of non-recyclable waste while recovering energy and ferrous metals. The facility will help process, treat and dispose of over 35 million gallons of sludge per year for the city of Baltimore. By processing and using more sludge within the state, Baltimore will save the city over a million dollars in hauling this waste out of state not to mention cutting costs in terms of manpower and carbon dioxide emissions. By using this processed sludge in biofuel power plants, the State and city of Baltimore can provide electricity for a considerable number of homes while equally increasing the renewable energy capacity/ generation of the city. This program would be in accordance with the State of Maryland EmPOWER Maryland Act along with the national energy goals of the United States. Currently treated sludge that is suitable for crop development is sold to local farmers in the state. This processed organic sludge provides several nutrients vital to staple crops such as corn. If this plant system design is implemented, the state will


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have more processed sludge, which can then be offered to farmers at a lower price for sale to out of state customers for a profit. This effort will drive the cost to farmers and reduce the cost of basic produce for Maryland residents. Additionally, the state and Baltimore City can reduce the inventory of artificial fertilizers and use processed sludge for application on state owned land such a public parks and highway medians. The funding for the design and construction of these facilities can be accomplished in part by using an US Department of Energy Block Grant. Additional sources of funding can be found in the private sector. Public –private partnerships have historically been shown to produce an efficient system that is able to respond quickly to emergent issues while providing a stable public service. This plan, if implemented, will reduce greenhouse emissions by changing the current balance of energy production in the state to more green sources. By burning sludge to generate power, the state and Baltimore City will fulfill two public needs of providing reliable energy and providing effective waste management. Operation and maintenance of these facilities will create and sustain high paying jobs that cannot be outsourced. Acknowledgements The authors would like to acknowledge the following people for their contributions, assistance, and guidance in completing this work of research. Many thanks for all hard work, dedicating time and helping us to complete a great milestone.

• Gerald Russell • Dr. LeeRoy Bronner • Morgan State University • State of Maryland

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Assessment Report, U.S. Department of Energy, Washington, D.C., 2009

[19] Tous, M., Bebar, L., Pavias, M. & Stehlik, P., Waste-to-Energy (W2E) Software- A Support Tool for Decision Making Process, Brno University of Technology. Institute of Process and Environmental Engineering, 2009

[20] http://coyotegulch.wordpress.com/2011/12/31/salida-wastewater-treatment-plant-update-project-is-on-schedule-for-completion-in-2013/

[21] http://en.wikipedia.org/wiki/Sewage_sludge_treatment

[22] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=5987334&tag=1&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D5987334%26tag%3D1

[23] http://personal.stevens.edu/~dvaccari/esim.html [24] http://terralys.fr/en/reglementation/software-

for-monitoring-sludge-application-and-composting/software-for-monitoring-sludge-application-and-composting/

[25] http://wiki.answers.com/Q/Advantages_and_disadvantages_of_Activated_sludge_treatment_plant

[26] http://www.asim.eawag.ch/ [27] http://www.ce.utexas.edu/prof/speitel/steady/st

eady.htm

[28] http://www.clemson.edu/ces/eees/outreach/sssp.html

[29] http://www.envirosim.com/downloads/updates/asm.php

[30] http://www.EPA.gov [31] http://www.holinger.com/index.php?id=748&L

=10 [32] http://www.mde.state.md.us/programs/Land/So

lidWaste/Documents/www.mde.state.md.us/assets/document/factsheets/sewagesludge.pdf

[33] http://www.mde.state.md.us/programs/ResearchCenter/ReportsandPublications/Pages/ResearchCenter/publications/general/emde/vol3no7/sewage.aspx

[34] http://www.sswm.info/category/implementation-tools/wastewater-treatment/hardware/semi-centralised-wastewater-treatments-7

[35] http://www.thecannongroup.com/product.asp?prodpassata=asbpprodba&unit=ba&ln=uk

[36] http://www.thewatchers.us/sludge_local_control.html

[37] http://www.unep.or.jp/ietc/publications/freshwater/sb_summary/10.asp

[38] http://www.unep.or.jp/ietc/publications/freshwater/sb_summary/7.asp

[39] http://www.wikipedia.org/sludge


ISBN: 978-960-474-331-5 178