CA Water Treatment Chapter 5

Good record keeping is essential for a successful preventive maintenance program because it allows for the tracking and documentation of maintenance activities, including inspections, repairs, and replacements. By maintaining accurate records, organizations can easily identify patterns or trends in equipment failures, determine the optimal maintenance schedule, and ensure that all necessary tasks are completed on time. Additionally, records provide valuable information for audits, compliance, and decision-making processes, helping to improve efficiency and reduce costs in the long run.

Preparing jar test reagents using samples of the chemicals actually used in the plant is a good practice because it allows for a more accurate representation of the actual conditions in the plant. Reagent grade chemicals may not have the same composition or impurities as the chemicals used in the plant, which can affect the results of the jar test. By using the actual chemicals, any variations or impurities present in the plant can be accounted for, leading to more reliable and realistic test results.

Having good records of actions taken during start-up/shutdown operations is beneficial for operators because it allows them to refer back to previous procedures and ensure consistency and efficiency in future start-ups/shutdowns. These records can serve as a reference guide, helping operators avoid mistakes, identify potential issues, and improve overall performance. By maintaining accurate records, operators can also track any changes made during start-up/shutdown processes and evaluate their impact on the system, leading to better decision-making and problem-solving in the future.

The measurement of filtered water turbidity is a reliable indicator of overall process performance. Turbidity refers to the cloudiness or haziness of water caused by suspended particles. By measuring turbidity, operators can assess the effectiveness of the filtration process in removing these particles. Higher turbidity levels indicate poorer filtration and potential issues with water quality. Therefore, monitoring turbidity provides valuable information for operators to maintain and improve the performance of the filtration system.

Regular visual observations and laboratory tests are necessary to assess the performance of the coagulation-flocculation process. These observations and tests help in monitoring the effectiveness of the process in removing suspended particles and contaminants from the water. By regularly evaluating the process, any issues or inefficiencies can be identified and corrected promptly, ensuring that the water treatment system is operating optimally. Therefore, it is important to conduct routine visual observations and laboratory tests to ensure the effectiveness of the coagulation-flocculation process.

Excessive mixing speeds, mixing time, and the buildup of heat can break down the polymer chain and reduce its effectiveness. This is because the mechanical stress and heat generated during excessive mixing can cause the polymer chains to break or become damaged, leading to a decrease in the polymer's properties and effectiveness. Therefore, it is true that excessive mixing can negatively affect the polymer's performance.

Samples should be analyzed as soon as possible after the sample is collected because the longer the sample sits without analysis, the greater the chance of degradation or contamination. Analyzing the sample promptly ensures that the results are accurate and reliable, as any changes or contamination that may occur over time can affect the analysis. Additionally, prompt analysis allows for faster decision-making and implementation of any necessary actions based on the results. Therefore, it is important to analyze samples as soon as possible after collection.

The statement suggests that after evaluating the jar test results, the dosage that yielded the best results should be applied to the water treatment plant operation. This implies that the dosage used in the jar test was effective in treating the water, and therefore should be implemented on a larger scale in the plant. By doing so, the water treatment plant can ensure that the same level of treatment is achieved consistently, resulting in improved water quality.

Overdoing or underdosing of coagulants can both have negative effects on the efficiency of solids removal. When coagulants are overdosed, it can result in excessive formation of flocs, causing clogging and reduced effectiveness in removing solids. On the other hand, underdosing of coagulants may not provide enough coagulation to effectively bind the solids together, leading to poor solids removal efficiency. Therefore, both overdoing and underdosing of coagulants can negatively impact the process and reduce the efficiency of solids removal.

If the water appears milky with a bluish tint, it suggests that the alum dose is excessive. Alum is commonly used as a coagulant in water treatment processes to remove impurities. However, if too much alum is added, it can cause the water to become cloudy or milky in appearance. The bluish tint indicates the presence of excessive alum, which is not desirable. Therefore, the statement is true.

The statement is true because in the enhanced coagulation process, the optimum dosages for acid, alkalinity, and coagulant are indeed determined by performing a series of jar tests. Jar tests are conducted to simulate the coagulation process on a small scale and to determine the most effective dosages of chemicals to achieve the desired water treatment objectives. By testing different dosages in jars, operators can observe the formation of flocs and determine the dosage that produces the best results in terms of turbidity removal and particle settling. This information is then used to optimize the treatment process on a larger scale.

Allowing untreated water to flow through a plant can have negative consequences on its health and growth. Untreated water may contain harmful chemicals, pollutants, or pathogens that can damage the plant's roots, leaves, or overall structure. It is important to ensure that the water used for irrigation or watering is treated properly to provide the plant with clean and safe water for optimal growth and development.

The explanation for the given correct answer is that the colloidal and dissolved organics in natural waters are indeed the result of decayed vegetable matter. When plants and other organic materials decay, they release organic compounds into the water, which can remain in a colloidal or dissolved form. These organic compounds can include substances such as humic acids, tannins, and lignins. Therefore, it is true that the colloidal and dissolved organics found in some natural waters are the end products of decayed vegetable matter.

When there are sudden increases in filtered water turbidity, the usual culprit is poor coagulation-flocculation process performance. Coagulation-flocculation is a crucial step in water treatment where chemicals are added to cause impurities to clump together and settle. If this process is not performed effectively, the impurities will not be properly removed, leading to increased turbidity in the filtered water.

The statement is true because the solids-contact process, also known as upflow clarifiers, is designed to combine the coagulation, flocculation, and sedimentation processes into a single basin. This process involves the addition of chemicals to coagulate and flocculate the suspended solids in the water, which then settle at the bottom of the basin. This integrated approach allows for a more efficient and compact treatment process compared to separate basins for each process.

Smaller sized particles, such as bacteria and fine clays and silts, do not readily settle out of water. Instead, they tend to remain suspended in the water due to their small size and low settling velocity. This is why water treatment processes often involve the use of coagulants and flocculants to help aggregate these particles and facilitate their removal. Therefore, the given statement is false.

The most important consideration in coagulation-flocculation process control is the selection of the proper type and amount of coagulant chemical(s) to be added to the water being treated. This is because the coagulant chemical(s) play a crucial role in destabilizing the suspended particles in the water, allowing them to come together and form larger flocs. The effectiveness of the coagulation process depends on choosing the right coagulant and determining the appropriate dosage to achieve the desired level of particle removal. Adjusting the alkalinity, keeping the floc in suspension, and maintaining a constant pH are important factors in the overall treatment process, but they are not the most critical consideration in coagulation-flocculation process control.

The statement suggests that the operator has effective control over both the pH and alkalinity of the source water. However, this is not necessarily true. While the operator may have some control over these factors, there are various natural and environmental factors that can also influence the pH and alkalinity of the source water. Therefore, it cannot be assumed that the operator has complete control over these parameters.

The purpose of the flocculation process is to create a floc of a good size, density, and toughness for later removal in the sedimentation and filtration processes. This is important because the floc helps to remove impurities and suspended particles from the water. By creating a floc with the desired characteristics, it becomes easier to separate and remove these impurities during the subsequent sedimentation and filtration steps.

Good communications require several key elements. First, it is important to advise other operators and support personnel of current process conditions, as this ensures that everyone is on the same page and can work together effectively. Additionally, advising others of unique or unusual events is crucial for maintaining transparency and addressing any potential issues. Clear and concise written or oral communications are essential for ensuring that information is easily understood and can be acted upon. Lastly, good record keeping is necessary for keeping track of important information and for future reference. Lengthy and wordy reports, on the other hand, can be counterproductive and can hinder effective communication.

Polymers are long chain molecules that are formed by the union of many monomers. Monomers are small units that can bond together to form a larger structure. In the case of polymers, these monomers join together through chemical reactions to create a chain-like structure. This chain can be made up of repeating units of the same monomer or different monomers. The process of polymerization allows for the creation of a wide range of materials with different properties and uses.

After starting up a piece of equipment, it is important to check for excessive noise, excessive vibration, leakage, and overheating. These checks are crucial to ensure the safe and efficient operation of the equipment. Excessive noise could indicate a malfunction or loose parts, excessive vibration could indicate misalignment or mechanical issues, leakage could indicate fluid or gas leaks that could be hazardous, and overheating could indicate problems with the cooling system or excessive friction. By checking for these items, any potential issues can be identified and addressed promptly, preventing further damage or accidents.

Using gas detectors is a reliable method for an operator to ensure that all underground structures are free of hazardous atmospheres. Gas detectors are specifically designed to detect the presence of gases, such as toxic or flammable gases, in the environment. By using gas detectors, operators can accurately and quickly identify if there are any hazardous gases present, allowing them to take appropriate measures to ensure safety, such as implementing ventilation systems or wearing appropriate protective gear. This method provides a more objective and accurate assessment compared to relying solely on smelling for gases or using other methods.

Coagulation and flocculation are water treatment processes used to remove particulate impurities and color from water. Coagulation involves adding chemicals to the water to destabilize and aggregate the suspended particles, forming larger particles called flocs. Flocculation then helps to further aggregate these flocs, making them easier to remove from the water through sedimentation or filtration. This process is particularly effective in removing nonsettleable solids and color from the water, improving its quality and clarity.

Alkalinity refers to the capacity of water to neutralize acids. It is a measure of how much acid can be added to a solution without causing a significant change in pH. Alkalinity is important in maintaining the stability of water bodies and is often measured in environmental and water quality assessments.

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The jar test does not exactly duplicate the flow-through conditions in a treatment plant. It is a laboratory test that simulates the treatment process on a small scale. The test involves adding chemicals to a sample of water and observing the effects, which may not accurately represent the conditions and dynamics of a full-scale treatment plant. Therefore, the statement that the jar test duplicates flow-through conditions in a treatment plant is false.

The detention time in a rectangular flocculation basin can be calculated using the formula:

Detention Time = (Volume of Basin) / (Flow Rate)

First, we need to calculate the volume of the basin:

Volume = Length x Width x Depth
Volume = 24 ft x 12 ft x 8 ft
Volume = 2,304 ft³

Next, we convert the flow rate from MGD to ft³/min:

0.7 MGD = 0.7 million gallons / 24 hours / 60 minutes
0.7 MGD = 972 ft³/min

Finally, we can calculate the detention time:

Detention Time = 2,304 ft³ / 972 ft³/min
Detention Time ≈ 2.37 min

Therefore, the correct answer of 35 min does not match the calculated detention time.

Based on the information provided, the correct answer of 68 lbs/day can be explained as follows: The flow rate is given as 0.9 MGD (million gallons per day) and the desired alum dose is 9 mg/L. To calculate the alum feeder setting in pounds per day, we need to convert the flow rate from MGD to gallons per day. 1 MGD is equal to 1,000,000 gallons per day. Therefore, 0.9 MGD is equal to 900,000 gallons per day. To find the alum feeder setting, we multiply the flow rate in gallons per day by the desired alum dose in mg/L and then convert it to pounds per day. So, 900,000 gallons/day * 9 mg/L * (1 lb/454,000 mg) = 68 lbs/day.

The average daily flow for a water treatment plant is 1.10 MGD (million gallons per day). The best polymer dosage is 2.2 mg/L (milligrams per liter). To find the total amount of polymer used in 30 days, we need to calculate the total volume of water treated in 30 days and then multiply it by the polymer dosage. Since the average daily flow is 1.10 MGD, the total volume of water treated in 30 days is 1.10 MGD * 30 days = 33 MGD. Converting MGD to liters, we get 33 MGD * 3.785 L/gal * 1,000,000 mg/g = 124,905,000 liters. Multiplying this volume by the polymer dosage of 2.2 mg/L, we get 124,905,000 liters * 2.2 mg/L = 274,791,000 mg of polymer used in 30 days. Converting mg to pounds, we divide by 453.6 (since 1 pound = 453.6 mg), which gives us 274,791,000 mg / 453.6 = 605 pounds of polymer used in 30 days. Therefore, the correct answer is 605 lbs.

The statement says that the theory of coagulation is very simple, and the answer is false. This suggests that the theory of coagulation is not simple, implying that it is complex or intricate.

The polymer dosage is calculated by converting the given values into the same units. First, we convert 28 pounds to milligrams by multiplying it by 453.6 (1 pound = 453.6 grams). This gives us 12,700.8 mg. Then, we divide this value by 1.6 million gallons to get the dosage per gallon, which is approximately 0.0079 mg/gallon. Finally, we convert this to mg/L by multiplying it by 1000 (since there are 1000 liters in a gallon), resulting in a dosage of 2.1 mg/L.

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The explanation for the correct answer, True, is that during the coagulation-flocculation process, chemicals are added to the water to destabilize and aggregate the suspended solids. These aggregated particles then form larger, heavier flocs that settle down as precipitates. Therefore, most of the sludge volume in this process is composed of these precipitates rather than the suspended solids that were removed.

The turbidity test provides an indirect measurement of the suspended solids concentration in a liquid. Turbidity refers to the cloudiness or haziness of a fluid caused by the presence of suspended particles. By measuring the turbidity, one can estimate the amount of suspended solids in the liquid. Therefore, the turbidity test is a useful tool for determining the level of impurities or contaminants in water or other fluids.

A representative sample is a sample portion of material or water that closely resembles the larger body of material or water being sampled in terms of its content and consistency. This means that the sample should accurately reflect the composition and characteristics of the entire population being studied. By ensuring that the sample is as similar as possible to the larger body, it increases the likelihood that the findings and conclusions drawn from the sample can be generalized to the entire population.

The enhanced coagulation process is designed to remove natural organic matter (NOM) from water. Natural organic matter can cause taste, odor, and color issues in water, as well as react with disinfectants to form harmful byproducts. By using enhanced coagulation, the process can effectively remove NOM, improving the overall quality of the water.

When working in a laboratory, an operator may be exposed to various potential hazards. Acid or caustic solutions can be hazardous if not handled properly and can cause burns or other injuries. Dangerous chemicals pose a risk if they are not handled, stored, or disposed of correctly, as they can be toxic or flammable. Glassware can break and cause cuts or puncture wounds. Reagents, which are substances used in chemical reactions, can also be hazardous if mishandled. Therefore, all the listed items - acid or caustic solutions, dangerous chemicals, glassware, and reagents - are potential hazards that an operator may be exposed to in a laboratory.

When selecting and using polymers for water treatment, it is important to consider that not all water supplies can be treated with equal success. This means that the effectiveness of the treatment may vary depending on the source of the water. Overdosing can result in accelerated head loss buildup, which can lead to clogging and reduced efficiency of the treatment system. Overdosing can also adversely affect coagulation efficiency, making the treatment less effective. Some polymers have dosage limitations, meaning that exceeding the recommended dosage may not provide any additional benefits. Additionally, some polymers may lose their effectiveness when used in the presence of a chlorine residual, which is important to consider when using chlorine for disinfection purposes.

Streaming current meters are devices used to optimize coagulant doses in water treatment processes. These meters measure the electrical charge on suspended particles in the water, which can indicate the effectiveness of coagulation. By monitoring the streaming current, operators can adjust the coagulant dosage in real-time to achieve optimal water treatment efficiency. This helps to improve the removal of contaminants and enhance the overall quality of the treated water.

The statement is false because coagulation is actually a rapid process that causes the gathering together of small, dispersed particles into larger, settleable particles. It is typically achieved through the addition of chemicals or the application of heat or electricity, rather than through slow stirring.

The most common laboratory tests for coagulation-flocculation process performance include measuring alkalinity, color, pH, temperature, and turbidity. These parameters are important indicators of the effectiveness of the process in removing impurities from water. Alkalinity helps determine the water's buffering capacity, color indicates the presence of contaminants, pH measures the acidity or alkalinity of the water, temperature affects the rate of reactions, and turbidity measures the clarity of the water by quantifying suspended particles. By monitoring these parameters, the efficiency of the coagulation-flocculation process can be evaluated and adjustments can be made if necessary.

Operators working around the coagulation-flocculation process may be exposed to potential hazards such as electrical hazards, open-surface water-filled basins (which can lead to drowning), rotating and mechanical equipment, slippery empty basins (which can result in falls), and toxic and explosive gases or insufficient oxygen. These hazards can pose significant risks to the operator's safety and well-being, and it is important for them to be aware of and take necessary precautions to mitigate these risks.

The correct answer is 92 mL/min because the flow rate is given in million gallons per day (MGD) and needs to be converted to milliliters per minute. 2.5 MGD is equal to 9,463,529 mL/min. The desired alum dose is 9 mg/L, which means that for every liter of water, 9 mg of alum is needed. Since there are 3.785 liters in one gallon, the alum dose in milliliters per gallon is 9 mg/L * 3.785 L/gal = 34.065 mg/gal. To find the setting on the liquid alum chemical feeder in milliliters per minute, we divide the alum dose in milliliters per gallon by the flow rate in gallons per minute: 34.065 mg/gal / 2.5 MGD = 92 mL/min.

The enhanced coagulation process is designed to produce the greatest possible reduction of disinfection by-products (DBPs), dissolved or suspended organic carbon (color), total organic carbon (TOC), and trihalomethanes (THMs). This process aims to remove these water quality indicators to improve the overall water quality and safety.

An efficient flocculation process involves a properly shaped basin for uniform mixing, mechanical equipment or other means of creating the stirring action, the proper stirring intensity, and the selection of the right stirring time (detention time). These factors are essential for achieving effective flocculation, which is the process of bringing together small particles in a liquid to form larger, settleable particles called flocs. A properly shaped basin ensures that the mixing is uniform throughout the system, while mechanical equipment or other means of stirring create the necessary agitation. The proper stirring intensity and the right stirring time are crucial for achieving optimal flocculation and settling of particles.

Changes in the coagulation process effluent quality, flocculation basin floc quality, and source water quality could indicate certain operator actions and possible process changes. The coagulation process effluent quality refers to the quality of the water after the coagulation process, and changes in this could indicate issues with the coagulation process itself. Similarly, changes in the flocculation basin floc quality could indicate problems with the flocculation process. Lastly, changes in the source water quality could also require adjustments in the coagulation-flocculation process to ensure effective treatment.

Underground structures can potentially have hazardous atmospheres due to various factors. Explosive gases can accumulate in confined spaces, posing a risk of explosions. Insufficient oxygen levels can occur in enclosed areas, leading to asphyxiation. Toxic gases can also be present underground, which can cause harm to individuals working or residing in these structures. Therefore, the correct answer includes explosive gases, insufficient oxygen, and toxic gases as potential hazardous atmospheres that may be encountered in underground structures.

In the enhanced coagulation process, several effects take place at the lower (optimum) pH that enhance coagulation. Firstly, flocculation is improved, which means that the particles in the water form larger and denser flocs, making it easier to remove them during the sedimentation process. Secondly, sulfuric acid addition prior to coagulant feed preconditions the organic compounds, making them more susceptible to coagulation. Thirdly, the coagulant demand decreases correspondingly to the degree of molecular dissociation, meaning that less coagulant is required to achieve effective coagulation. Lastly, the humic and fulvic molecules dissociate (separate) to a lesser degree, which prevents them from interfering with the coagulation process.

The jar test is used to replicate the conditions in a water treatment plant, specifically the relation between detention times, mixing conditions, and settling conditions. Detention time refers to the amount of time water spends in a treatment process, while mixing conditions determine the effectiveness of chemical reactions and the distribution of chemicals in the water. Settling conditions refer to the ability of particles to settle out of the water. By conducting jar tests, operators can optimize these factors and determine the most efficient treatment process for the plant.