Wastewater Test

Foaming in an anaerobic digester can be prevented by adjusting the pH level of the digester. This helps to maintain the balance of microorganisms involved in the digestion process and reduces the risk of foaming.

When the F/M ratio is increased in an aeration basin to maintain the same dissolved oxygen level, the operator needs to increase the aeration rate. This helps to ensure that sufficient oxygen is provided to the microbial community despite the increase in organic matter loading.

To calculate the gallons per minute of sludge that must be pumped, you can use the formula: Gallons per minute = (lbs/day of solids) / (MLSS concentration in mg/L * 8.345). Plugging in the values: 2,500 / (6,000 * 8.345) gives you 35 gallons per minute.

Foaming in the aeration tank is often a sign of excessive waste activated sludge (WAS) in the system. By decreasing the amount of WAS, the operator can reduce the foaming and maintain a more optimal environment for the treatment process.

A worn impeller in a centrifugal pump would result in a decrease in efficiency as it leads to reduced pumping capacity and can also cause cavitation, impacting the overall performance of the pump.

When one phase is lost in a three-phase motor, the motor will experience unbalanced currents and may overheat, leading the thermal overloads to stop the motor to prevent damage.

High discharge head pressure can cause leaking around the seals and plunger as it puts excessive strain on the components, leading to failure.

As grit accumulates in a grit chamber, it reduces the available space for wastewater flow, leading to an increase in velocity. However, the settleability of the grit decreases as more particles settle out due to the reduced flow velocity.

An increase in suspended solids can block UV light penetration, reducing the effectiveness of the disinfection process and therefore decreasing process efficiency.

Slaking is the process of adding quicklime to water to produce slaked lime or calcium hydroxide.

Dry Chemical fire extinguishers are suitable for oil and electrical fires as they form a barrier against oxygen and smother the fire. Water, Carbon Dioxide, and Foam extinguishers would not be effective and could even make the fire worse in these situations.

When a vacuum filter produces a wet cake, it is often due to the drum speed being too fast, causing improper filtration and inefficient cake drying. Factors such as insufficient vacuum pressure, drum speed being too slow, or incorrect filter media selection can also contribute to this issue but the primary cause is usually the drum speed being too high.

An Imhoff cone is used to measure settleable solids, which are solids that settle at the bottom of the cone after a certain period of time. Suspended solids remain suspended in water, dissolved solids are completely dissolved in water, and colloidal solids are particles that are smaller than settleable solids and remain suspended for a longer period of time.

Positive displacement pumps are favored for feeding chemicals because they discharge a consistent volume, which is crucial for accurate chemical dosing.

In a well balanced activated sludge system, the presence of flagellates, ciliates, and rotifers indicate a healthy and effective treatment process. These microorganisms contribute to maintaining the right balance in the sludge for optimal wastewater treatment.

An overloading of BOD in the aeration tank would cause the microorganisms to consume more oxygen to break down the organic matter, leading to an increase in the oxygen uptake rate.

Performing lockout/tagout ensures that the pump is isolated from its energy source, preventing accidental startup during maintenance work and ensuring the safety of the individual working on the pump.

When shutting down chlorine feed to a chlorinator, it is important to start at the chlorine container because this is where the supply of chlorine is coming from. Turning off the chlorine feed at the container ensures that no more chlorine will be added to the system.

A backflow check valve is specifically designed to prevent water from flowing back into the chlorinator, ensuring that only water flows in the desired direction.

Dissolved air flotation thickener works effectively with waste activated sludge due to its characteristics and composition.

To calculate the velocity of flow in feet per second, we first need to convert 500 gallons per minute to cubic feet per second. Then, using the formula for calculating velocity in a pipe (velocity = flow rate / cross-sectional area), we can determine the correct answer of 3.3 feet per second.

Engaging the fan before the blower reaches normal operating speed can cause unnecessary strain on the equipment. It is important to ensure that the blower is running at its intended speed before engaging the fan for optimal performance.

Ferric chloride is most effective for coagulation in wastewater treatment when the pH and alkalinity levels are high. High pH and high alkalinity conditions help promote the formation of floc particles and improve the coagulation process.

The correct way to withdraw sludge from a fixed-dome digester is to match the withdrawal rate to the feeding rate to maintain a balanced system and ensure proper functioning of the digester.

Polymers are not typically associated with toxic fumes, fire hazard, or chemical burns. However, slipping due to their slippery nature can be a common safety hazard when working with polymers.

Ammonia nitrogen can react with chlorine to form combined chlorine, resulting in a temporary drop in free chlorine levels followed by a rise once the reaction is complete.

Anaerobic digestion is a process where microorganisms break down organic matter in the absence of oxygen, leading to the production of carbon dioxide and methane as major gases.

In this scenario, as the MLSS has increased, more aeration is needed to maintain the same DO levels, hence the correct adjustment is to increase the aeration rate.

The correct answer involves adjusting the air flow to ensure optimal dissolved oxygen (DO) levels throughout the aeration tank, allowing for effective treatment of the wastewater.