Introduction

Over the last decade, preserving natural resources has been a top priority in society. Among these natural resources, water is among the most popular. In particular, securing safe drinking water has become the general focal point, and the Environmental Protection Agency (EPA) has outlined several mandates to ensure safe drinking water is distributed among the public. However, water treatment plants across the United States do not always follow these regulations, and harmful chemicals and byproducts exist in drinking water as a result. According to the New York Times analysis of federal data, more than 20% of the United States water treatment systems do not provide water immune to certain chemicals or harmful bacteria (Duhigg 1).

Background

When the Clean Water Act was drafted in 1974, its original provision was to clean US waterways, providing “fishable and swimmable” water to the public (“Troubled Waters” 1). However, even after 38 years, this act has not been completely fulfilled, due to lack of enforcement and political entanglement. These factors are discussed more thoroughly in the next few sections.

Environmental Protection Agency

The Environmental Protection Agency was created in 1972 to do exactly what its title states: to protect all sectors of our environment from harmful treatment, therefore preserving the “green” side of all life. In particular, the Safe Drinking Water Act is most relevant to this report. It was set down to ensure that water would no longer carry harmful bacteria or chemicals from its source to homes, businesses, etc. The main mandate of this report states that “the Federal Government commits to maintaining and improving its partnership with the States in administration and implementation of the Safe Drinking Water Act” (“Clean Water…” 1)

In summation, the federal government is ultimately responsible for adherence to these acts, but the states are required to submit accurate information regarding their public water treatment in order to justify this enforcement.

Debate

Protecting the environment is a continuous debate, especially in politics. Most often, liberals tend to vote for greater environmental protection laws, whereas conservatives are not as concerned. However, I believe that formulating a compromise that can follow an efficient budget, allow advancement in infrastructure, and protect nature will soon demolish the controversies between the liberal and conservative agenda. However, creating this compromise is not as simple as it sounds. Most recent arguments from these two viewpoints regarding the environment, and specifically drinking water, arose during the Bush administration. Sometimes claimed an “assault” on the Clean Water Act, the Bush administration cut the budget of the EPA so that retaining national inspections of its regulations was difficult to complete (“Troubled Waters” 15). This budget realignment would take away the federal authority of the EPA, and place a greater responsibility on the States to uphold their water treatment regulations. Another important decision under the Bush administration was to allow “sediment runoff at oil and gas construction sites” into surface water, which would increase water treatment costs (“Troubled Waters” 16).

These two actions under the Bush administration have frequently been used to attack the conservative agenda, but like every two-sided story, the liberal view is not completely innocent. For example, after “$2.3 million in federal grants” were given to the EPA to improve rural drinking water, not all of that money left Washington, but served as campaign money for liberal lobbyist (Winston 1). With the majority party being republican at this time, allegiance with the EPA and its work across the nation was skeptical to say the least. Therefore, it creates a barrier between the political views of Republicans and Democrats. In order to adhere to each side, a compromise must be made, but it ultimately lies in the hands of the water treatment plants and their administration across the nation.

I believe that insuring safe drinking water is a process of treatments that each water treatment plant must focus on. The next three sections provide the foundations of these treatments, illuminating the advantages and disadvantages of each. In addition, techniques of membrane filtration and chemical filtration will be presented from experimental data to concur a precise evaluation of how to improve drinking water; this data and research on a broad scale will determine a concise and specific solution on how to improve the drinking water at Johns Hopkins University at Homewood campus.

Methods of Cleaning Drinking Water

In general, there is no one way to clean water effectively, but a number of ways that are placed in a cycle to perform the best treatment. Doctor Edward Bouwer, Chair and Abel Wolman Professor in Environmental Engineering at Johns Hopkins University, commented on these cycles of treatments, referring to them as “multiple barriers”. He said that in order to extract the highest level of contaminants, applying multiple barriers in each water treatment plant is necessity. Figure 1 on page 4 demonstrates a simple filtration system utilizing the multiple barrier theory. Where there are many filtration methods, determining which ones to use and in which order are two major questions that are constantly being tested. Table 1 shows source water categories and their general purification system category. Out of these purification steps, basic filtration (sand, sedimentation, coagulation, and flocculation), membrane filtration, and chemical extraction will be discussed further.

[pic]
Figure 1- a typical flow chart of the water filtration system. Multiple barriers are represented by the flocculation tank, sedimentation basin, and filtration sections of this diagram, each used to separate impurities from the water.1

Code Source water category Code Purification system category____________________
A Dam-released water 0 Chlorination
B Dam direct intake water 1 Membrane filtration
C Surface water 2 Slow sand filtration
D Lake and pond water 3 Manganese sand filtration
E River-bed water 4 Coagulation+rapid sand filtration
F Shallow well water 5 Coagulation+sedimentation+rapid sand filtration
G Deep well water
H Spring water 6 Coagulation+sedimentation+ozonation+GAC+ Rapid sand filtration
I other 7 Biofiltration etc._________________________________

Table 1- Categories and their codes for source water and purification systems.2

1 Findlay, Richard, comp. "Municipal Water Treatment." Pollution Probe (2002): 1-77. Pollutionprobe.org. June 2002. Web. 4 Nov. 2010.
2Hayashi, N, M Fujiwara, H Yokota, and H Furumai. "Evaluation of Source Water Quality for Selection of Drinking Water Purification System." Water Science and Technology: Water Supply, 8.3 (2008): 273.
General Filtration Techniques

1. Sand Filtration- Slow sand filtration has been around since the 1800s, and is now used as the first filtration used in a multiple barrier system. A basic overview of sand filtration is demonstrated in Figure 2. A high surface area filter bed is aligned so that the raw water can pass through a medium and block pathogens from entering the treated water. In the most effective systems, diseases such as Phytophthora and other nursery diseases are controlled by using a slow filter and small particle size of the sand (Huisman 5-6). The most notable advantages of a slow sand filter include i. Easily installed ii. Low cost iii. Low energy consumption

[pic]
Figure 2 – overview of a sand filtration system.3

2. Sedimentation- Another type of filtration, sedimentation uses a large tank that pressurizes the collation of large particles of matter to be removed from the water. This unwanted matter settles at the bottom of the tank, where the excess filtered water is then passed on to another cycle of filtration, usually either coagulation or flocculation (“Water Treatment” 5). 3. Coagulation and Flocculation – These two methods of filtration are very similar, focusing on the same aspect of electrolytic extraction. The smaller particles inside the water already treated by sedimentation have the same charge, and repulse each other. This means that an opposite charge can be applied to the water to attract these particles, forming a precipitate. This new solid can then be filtered out, leaving clear and relatively pure water. Aluminum and lime are some of the most common chemicals used in forming the opposite charge, and Iron hydroxide is a common precipitate that forms (“Water Treatment” 5). However, these chemicals can often bypass inspection and enter drinking water cycle, as discussed in the Chemical Abstract section of this report.

3 Huisman, L., and W. E. Wood. "Slow Sand Filtration." Oasisdesign.net. Colorado State University, June 1991. Web. 4 Nov. 2010.
Membrane Filtration

[pic] Figure 3- a basic membrane filtration unit.4

Membranes are a relatively new technology that has been applied to water filtration. Whereas the basic filtration systems discussed above are good at removing large organic matter, membranes provide an advantage by removing pathogens from the drinking water (Yamamura 1). They also remove bacteria and turbidity, and even dissolved salts, which is not shared by sand filtration, sedimentation, or coagulation/flocculation (Jacangelo 68). Membranes require a relatively low pressure, but require a large amount of energy to operate. The high energy requirement is mostly due to a process called membrane fouling, where the permeability of the membrane becomes deteriorated over time, which cannot be fixed by physical cleaning (Yamamura 1). Therefore, membrane filtration is a technology not yet understood to work at its full potential. The most common membrane filtration systems are ultrafiltration, nanofiltration, and reverse osmosis.

4 "Water Quality." Kamloops.ca. City of Kamloops. Web. 5 Nov. 2010. . • Ultrafiltration- This type of membrane works well at removing turbidity, microorganisms, and large organic molecules. The size of these particles range from .001 to 10 microns. Water, salt, and small molecules are not removed, but the most important harmful material is removed, which are generally molecules that can combine with chlorine to form dangerous compounds. This type of membrane runs at a pressure ranging from 15 to 75 psig (Jacangelo 68). This process is advantageous because it reduces the amount of chemicals needed to clean drinking water, eliminating byproducts (Jacangelo 70). Figure 4 demonstrates how ultrafiltration works.

[pic]

Figure 4- An ultrafiltration membrane within a water filter.5

• Reverse osmosis- This type of membrane uses the smallest pore size of the three membranes discussed in this report, with typical sizes ranging from .0001 to .001 microns. The pressure is greater than the others, however, running at a range of 200 to 1200 psig. This process is used for seawater, where ions and other small particles are too small to use any other membrane (Jacangelo 68). In order for this process to work, two concentrations of water- on high, one low- are separated by a semi-permeable membrane. Pressure is applied to the higher concentrated contaminated water, migrating water molecules from the high concentration to the low. This removes the microns of organic matter, salt, and other harmful materials, filtering the water (“Water Treatment” 7). Figure 5 on the following page shows this process.

5 "Cleanest Home Water." TradeNote.net. 6 July 2006. Web. 5 Nov. 2010. .

Figure 5 – Reverses osmosis in water treatment.6

• Nanofiltration- This type of membrane has the most positive outlook for use in the future, as its pathogen removal is relatively high compared with low energy consumption (Bursill 4). As for separation characteristics, nanofiltration is between ultrafiltration and reverse osmosis, where it removes salts and other particles to as small as .001 microns. The pressure used is higher than ultrafiltration but less than reverse osmosis, at values between 75 and 250 psig (Jacangelo 68).

Chemical Filtration Using Nanoparticle-Conjugated Polymer Nanocomposites

Often times the filtration techniques and membrane technology are not enough to remove metallic ions from the water. These ions can be very harmful if ingested, the severity of which will be discussed in the next section of this report. Not only can the ions be harmful, but certain elements such as Chromium (Cr), Nickel (Ni), and Zinc (Zn) can form radionuclides within the water, also passing through filtration and being potentially dangerous (Khaydarov 2). One proposed method to prevent these metallic ions from entering the drinking water distribution cycle is by using carbon nanoparticle-conjugated polymer nanocomposites. In theory, ultrafiltration and water soluble polymers are used together in a manner that attaches the ions to these polymers, creating a precipitate that cannot pass through the membrane. This is advantageous because it uses relatively low energy combined with high efficiency in the removal of metal ions (Khaydarov 1).

In summary, each methods of filtration discussed above are what water treatment plants use to clean drinking water. Utilizing the appropriate combination of these techniques under strict inspection is necessary to insure a safe environment and humane public drinking source. Next, the chemicals, bacteria, and organic matter that can pass through these treatments will be analyzed to demonstrate why strict supervision of water treatment must be conducted.

6 "Water Treatment." Uwaterloo.ca. Cyberspace Chemistry. Web. 4 Nov. 2010. .
Harmful Chemicals in Drinking Water

Water in itself is an aqueous medium for the occurrence of chemical reactions, varying from ion related dissociation to reactions that create disinfection by-products (DBPs). Therefore, filtering drinking water to eliminate all this material is very difficult to complete. This section is dedicated to the most common chemicals and substances within drinking water and how they form.

Natural and Organic Matter

Doctor Edward Bouwer dedicates his filtration research into two separate types of unwanted substances in water: natural and unnatural. He described natural substances as those that are mostly inorganic, such as arsenic, lead, and selenium. Unnatural substances are those that humans have contributed in supplying, particularly organic matter, pesticides, or metallic substances. In treating for these substances, the filtration techniques can be used, but are somewhat ineffective if the quantities are too high. This can lead to membrane fouling (Yamamura 1). However, treating for natural organic matter has and continues to be monitored by testing membrane filtration with backflow and chemical cleaning (Jacangelo 71).

A major source of organic matter, as well as bacteria, viruses, and parasites, is sewage. One problem of using surface water is that it is often “blended” with sewage, allowing these harmful materials to enter the filtration cycle (“Troubled Waters” 14). A surplus of natural organic matter within potential drinking water lowers filtration efficiency and increases membrane fouling (Yamamura 1). The Clean Water Act set regulations for this problem, but the Bush administration argued that wetlands, small streams, and ponds that clean surface water were outside the EPA’s jurisdiction, and allowed pollutants to be increased by sewage blending within these small water ecosystems (“Troubled Waters” 14). This debate exemplifies the compromise needed (as discussed on page 6 of this report) to allow human progress and environmental protection within the same ecosystem.

Disinfection By-Products (DBPs)

One method of eliminating the natural and artificial organic matter within drinking water filtration is by using chemicals to clean the filters and water, particularly using chlorine. Chlorine has proven most affective in destroying “harmful waterborne pathogens”, but it also is a source for the creation of DBPs (Liviac 2638). These DBPs have the potential to be “mutagenic, teratogenic, and/or carcinogenic” (Gentlemen 2). Long term effects from chlorinated water are particularly harmful to the body, not because of the chemical, but the DBPs it creates.

Health Effects of DBPs

More than 600 DBPs have been discovered since 1976, when the potential of these DBPs were seen as carcinogenic. However, this is believed to be less than half of all DBPs that form when chlorine is used to clean water. In attempt to dissolve the problems associated with DBPs in drinking water, the Environmental Protection Agency conducted a multi-national study called “Four Lab Study” (Pressman 1). The EPA main concern involves the health effects these DBPs cause, some of which are: • Bladder cancer • Spontaneous abortion • Low birth weight • Clastogenic and aneugenic effects • Genotoxic

In order to determine how to eliminated the DBPs, certain experiments are being conducted to not only name these products, but to find alternatives to chlorine treatment that proves (a) just as effective in metallic and organic removal, and (b) less apt to form DBPs. One of these tests included inducting two halogenated acetaldehydes (DBPs) into cultured cells to see their effects on DNA. (Liviac 1). Although the experiment included complex DNA analysis, the results were simple: DBPs are genotoxic and an alternative needs to be found (Liviac 7).

In summary, natural and unnatural organic and inorganic matter, disinfection by-products, and bacteria are harmful substances found in surface water that needs to be treated for drinking water. The filtration techniques discussed on pages 4-7 are used to reduce these products, but the addition of chlorine to maintain these processes can cause damaging DBPs.

Drinking Water Distribution Process

Thus far, the process of filtering drinking water and the chemicals in which are treated have been identified, but this is not the end of the process, it still must be delivered to the consumer. In properly supervised and disciplined water treatment plants, the drinking water that leaves the plant is as clean as technologically possible; however, the time between when the water leaves the plant to when it is ingested is where most nonquantifiable error occurs. This section describes the errors that occur during this distribution process, as well as discussing different types of piping and their advantages and disadvantages.

From Source to Tap

In general, inspection of the water quality is done at the source of its cleaning. It is highly assumed that the water that leaves this source maintains this level of purity all the way to the tap where the water is used for drinking, cleaning, etc. This assumption is not correct. In fact, chlorinated DBPs and bacteria most often form at this stage. As the water leaves the plant, it flows through a variety of “storage tanks, valves, pumps, and pipes” (“Distribution Systems…” 1). These pipes are mostly underground, and the water is subject then to a variety of problems. Most significant of these problems is corrosion. When piping is not used, trucks with large tanks transport the water. The water is relatively stationary for a long time compared to a constant flow as that in a pipeline system, and DBPs can form from chlorine within the tank and the favorable environment the water creates for chemical reactions. Doctor Bouwer discussed this situation, saying that the water can be stored for over a week at a time, greatly aiding the chemical medium in which these DBPs are formed. Figure 6 depicts the distribution system.

[pic]
Figure 6- Water Distribution System.7

Piping

Most traditional piping systems are made from metal alloys of different concentrations and material; Johns Hopkins University at Homewood campus uses pipes made from ductile iron to deliver its drinking water. Ductile iron piping is very susceptible to corrosion. Specifically, ferrous iron is in these pipes. When this type of iron contacts oxygen, it reacts to form insoluble iron oxides, which enter the water and ultimately is taken into the body upon drinking the water (“Iron…” 1). This type of corrosion can occur when there is a leak in the pipes, or if they are not sealed properly as to allow oxygen to enter. The corrosion of iron damages the pipes, disrupting pure water flow, and also causes the water to change color; however, unlike lead and copper, it does not directly cause adverse health affects, but impurities and microorganisms are indirect substances that are formed from this corrosion and can cause adverse health affects (“Iron…” 2). The EPA does not regulate the amount of iron allowed in drinking water, placing a great responsibility on water treatment administration to focus there efforts in applying their own regulations.

7 "Rehabilitating Small-scale Piped Water Distribution Systems." WHO. Ed. WHO. World Health Organization. Web. 21 Nov. 2010.
Conclusions

Safe drinking water is a topic for many different aspects of society. The Environmental Protection Agency is responsible for enforcing the mandates of the Safe Drinking Act, but cannot enforce every water treatment plant effectively because of lack of funding. However, this funding must be regulated so that the money is going to the filtration plants and not in lobbyist recreation. The simple methods of filtration as well as membrane filtration are used by water filtration plants, but are only effective if they are used in a “multiple barriers” system, and tested regularly for improvements. This responsibility ultimately lies with the administration of these plants. Relatively speaking, water that leaves the filtration plant is safe for immediate use, but can become harmful if the time of its consumption is prolonged. Therefore, speeding up this process will greatly eliminate harmful material in the drinking water. Also, the piping at Johns Hopkins University at Homewood campus needs to improve to eliminate metallic impurities. If each area of the filtration and distribution system is carefully monitored and improved, public drinking water will be safe and pure.

Recommendations

In order to ensure Johns Hopkins University at Homewood campus is doing all it can to provide safe, pure drinking water, I propose that the certain precautionary measures are made after the water leaves the water treatment plant: 1. The drinking water should be regulated so that it must be delivered within 2 days of its departure from the water treatment plant. Any longer than that, DBPs begin to form exponentially faster than if supervised to this time. Estimated cost: $5,000 annually 2. Ductile iron piping should be replaced with PVC piping, eliminating corrosion. Maintenance of these pipes should be conducted annually, ensuring that all valves and connections are working properly. Estimated cost: $20,000 3. The drinking water should be chemically tested annually, recording any DBPs or other impurities that exist so that they can be accounted for. Estimated cost: $2000 annually 4. For metal piping between Johns Hopkins University at Homewood campus and the corresponding water filtration plants, additional filters that use carbon nanoparticle-conjugated polymer nanocomposites can be added to reduce the metallic ions into large polymers that can be filtered out. This will not be billed directly to Johns Hopkins University, but rather paid for by the city of Baltimore. Estimated total cost: $27,000 for the first year, $7,000 annually after.