Mastering Volatile Solids Loading in Wastewater Management

An anaerobic digester has a diameter of 60 feet and a sludge depth of 20 feet. How is the volatile solids loading calculated if 9,500 pounds of sludge with a 70 percent volatility is pumped daily?

• A. 0.10 lbs/day/cu ft
• B. 0.12 lbs/day/cu ft
• C. 0.15 lbs/day/cu ft
• D. 0.20 lbs/day/cu ft

Answer: (B)

To calculate the volatile solids loading in an anaerobic digester, the process involves first determining the total volume of the sludge in the digester and then calculating the volatile solids content based on the given parameters. In this scenario, the diameter of the digester is 60 feet, and the sludge depth is 20 feet. The volume can be calculated using the formula for the volume of a cylinder: Volume = π * (radius)^2 * height. The radius is half of the diameter, so it is 30 feet. Thus, the volume of the digester becomes: Volume = π * (30 feet)^2 * 20 feet = π * 900 * 20 = 18,000π cubic feet. Now, regarding the sludge, it is mentioned that 9,500 pounds of sludge with a 70% volatility is pumped daily. First, we need to determine the total amount of volatile solids. Since 70% of the sludge is volatile, we calculate: Volatile solids = Total sludge weight * Volatility = 9,500 lbs * 0.70 = 6,650 lbs. Now, to find the volatile solids loading per cubic foot, we divide the total volatile solids by the volume of

When it comes to wastewater management, understanding how to handle sludge efficiently is vital. You might think of a complex puzzle where each piece fits into a larger picture—one that includes not only the math but also the science behind the processes. So, let’s break down the calculation of volatile solids loading, a fundamental concept you'll need for the Wastewater New York State Exam.

To illustrate, let’s imagine you’re in front of an anaerobic digester with a diameter of 60 feet and a sludge depth of 20 feet. Now, how do we turn that into useful information for our calculation? The first step is to figure out the volume using the classic cylinder volume formula: “Volume = π * (radius)^2 * height.” Here’s the catch: the radius is half of the diameter, so we have 30 feet as our radius.

Thinking spatially, the volume calculation goes like this:

Volume = π * (30 feet)^2 * 20 feet.

When you do the math, that comes out to roughly 18,000π cubic feet. Pretty neat, right? But the real fun starts when we dive into the numbers regarding the sludge itself. We find out that 9,500 pounds of sludge, pumped daily, has a 70% volatility. This is where understanding the volatility percentage becomes crucial.

Now, let’s calculate the amount of volatile solids:

Volatile solids = Total sludge weight * Volatility, or in simpler terms, 9,500 lbs * 0.70 = 6,650 lbs. At this point, you might be wondering, “What does all this mean for the solids loading?” It’s simple! Figure out how many pounds of volatile solids you have for each cubic foot of digester volume.

So, we take that 6,650 lbs and divide it by our total volume of 18,000π cubic feet. When you calculate that out, it gives you the volatile solids loading, which, in this scenario, comes out to be 0.12 lbs/day/cu ft. So, for our exam question, that’s option B!

But what’s the takeaway here? Understanding these calculations not only helps you pass exams like the New York State Wastewater exam but also equips you with knowledge that can impact real-world wastewater management practices. It’s about more than just numbers; it’s about the role you will play in keeping our water sources clean and sustainable.

You know, as we talk about these concepts, it’s like piecing together a compelling narrative about our planet’s resources and how we manage them. That’s what makes this field so fascinating! There’s always something new to learn, and the knowledge we gain today lays the groundwork for tomorrow’s solutions in wastewater management.