DAGYEE Redefines Fine Screening with New "Intelli-Flow" Internally Fed Drum Screen

# DAGYEE Internal Drum Screen Systems: The Complete Technical FAQ

## Introduction to DAGYEE Fine Screening Solutions

**About This Guide:**

This technical guide is intended for civil engineers, wastewater plant operators, and industrial project managers who are designing **Headworks** for **Wastewater Treatment Plants (WWTP)** or managing industrial effluent.

As a specialized manufacturer, **DAGYEE** focuses on engineering high-performance **Internal Drum Screens**. Unlike standard distributors, DAGYEE specializes in **customizing** the drum diameter, perforation size, and channel integration to meet your specific hydraulic and solids loading requirements.

## Section 1: Fundamentals & Working Principles

### **Q1: What is an Internal Drum Screen, and how does it function?**

**Internal Drum Screen** (often called an Internally Fed Rotary Drum Screen) is a mechanical **Fine Screen** used for the advanced separation of solids from liquids.

**The Operating Principle:**

1. **Inlet:** The raw wastewater enters the equipment through a central inlet pipe and is discharged into the *inside* of the rotating drum.

2. **Separation:** The water flows radially from the inside of the drum to the outside, passing through the filter mesh (either **Perforated Plate** or **Wedge Wire**).

3. **Retention:** Suspended solids, trash, and fibers are retained on the inner surface of the drum cylinder.

4. **Transport:** As the drum rotates, internal spiral flights (baffles) transport the trapped solids axially toward the open end of the drum.

5. **Discharge:** The solids fall out of the drum mouth into a collection hopper or directly into a **Screenings Compactor**.

### **Q2: What is the difference between an "Internal" and "External" Drum Screen?**

This is a critical distinction in **Solid-Liquid Separation**.

* **External Drum Screen:** Water flows onto the *outside* of the drum and passes in. Solids stay on the outside and are scraped off. Best for sticky, greasy solids (like slaughterhouse waste).

* **Internal Drum Screen:** Water flows into the *inside* of the drum. Solids stay inside. Best for high-volume **Municipal Sewage** and protecting downstream membranes because it creates a closed loop where solids cannot bypass the screen.

### **Q3: Why is this screen preferred for MBR (Membrane Bioreactor) Protection?**

**MBR Protection** is the #1 application for the DAGYEE Internal Drum Screen.

Hollow fiber membranes in MBR systems are extremely sensitive to hair, fibers, and sharp debris.

* **Perforated Plate Technology:** We typically use perforated plates with 1mm or 2mm circular holes. Unlike slot screens (wedge wire), circular holes prevent long strands of hair or textiles from "orienting" themselves and slipping through the gap.

* **High Capture Rate:** The Internal Drum Screen offers a superior **Capture Rate** (often >90% for hair and fiber) compared to bar screens, ensuring the longevity of your expensive membrane modules.

### **Q4: Does the machine perform dewatering?**

Yes. The **Internal Drum Screen** is not just a separator; it acts as a preliminary dewatering device.

As the solids are pushed by the internal flights toward the discharge end, they roll over themselves. The residual water drains back through the screen mesh. By the time the solids reach the discharge chute, they are significantly drier than solids removed by static screens, reducing the volume for disposal.

## Section 2: Technical Specifications & Customization

### **Q5: What filtration precisions (Mesh Sizes) does DAGYEE offer?**

We customize the filtering media based on your process needs.

* **Perforated Plate:** Available in 1mm, 2mm, 3mm, and 6mm hole diameters. This is the standard for **Fine Screening** in municipal plants.

* **Wedge Wire:** Available in 0.25mm to 3.0mm slots. This is preferred for industrial applications requiring heavy solid loads or sticky materials.

* **Customization:** If you have a specific particle size limit, DAGYEE engineers can fabricate screens with non-standard hole sizes to guarantee the effluent quality.

### **Q6: What materials are used in construction?**

Durability in corrosive environments is paramount.

* **SS304 Stainless Steel:** The industry standard for general municipal sewage.

* **SS316/316L Stainless Steel:** Mandatory for high-salinity wastewater (seafood processing, desalination intake) or acidic industrial effluent.

* **Drum Wheels/Trunnions:** Made from high-wear-resistant Nylon or Polyurethane to ensure smooth **Rotary Drum** movement and quiet operation.

### **Q7: Can DAGYEE customize the dimensions to fit my channel?**

Yes. Many clients are retrofitting old plants where space is limited.

* **Drum Diameter:** We manufacture drums ranging from 600mm up to 2000mm+ in diameter.

* **Channel Width:** We can adjust the frame width to fit into existing concrete channels.

* **Inlet Piping:** The flange size and height can be modified to match your existing gravity pipe or pumped line.

We do not force you to adapt your civil works to our machine; we adapt our machine to your works.

### **Q8: Is the system fully enclosed?**

Yes. A major advantage of the DAGYEE Internal Drum Screen is the **Enclosed Design**.

* The entire drum assembly is covered by a stainless steel hood.

* **Odor Control:** This containment prevents foul odors from escaping into the plant atmosphere.

* **Safety:** It prevents operators from accidentally touching moving parts.

* **Ventilation:** We can provide a flange connection on the cover to connect to your facility's central odor scrubbing system..

## Section 3: Operational Performance & Efficiency

### **Q9: How does the Backwash (Self-Cleaning) System work?**

Even the best screens can blind over time without cleaning.

* **Spray Bar:** DAGYEE installs a high-pressure **Spray Bar** assembly on the *outside* of the drum cylinder (spraying inward).

* **Operation:** As the drum rotates, the spray bar blasts water through the mesh from the clean side to the dirty side. This dislodges any particles stuck in the holes and forces them back inside the drum to be discharged.

* **Automation:** The spray can be set to run continuously or intermittently via a timer or pressure differential sensor to save water.

### **Q10: What is the Head Loss (Hydraulic Resistance) through the screen?**

**Head Loss** is a critical factor in hydraulic profiling.

* A clean Internal Drum Screen typically has a very low head loss (approx. 150mm – 300mm).

* However, as solids accumulate, head loss increases.

* **Safety Bypass:** DAGYEE designs the tank with an overflow weir or a bypass channel. If the screen blinds completely or power fails, the water will flow over the weir to prevent upstream flooding.

### **Q11: What flow rates can DAGYEE screens handle?**

Flow capacity depends on the Drum Diameter and the Perforation Size.

* **Small Units:** ~30 – 50 m³/hr (often used for industrial side-streams).

* **Medium Units:** ~100 – 500 m³/hr.

* **Large Units:** >1000 m³/hr.

* *Note:* A 1mm screen handles significantly less flow than a 3mm screen of the same size. DAGYEE engineers run calculations to ensure the **Surface Area** is sufficient for your Peak Flow.

### **Q12: How does the Sludge Discharge mechanism work?**

There are no moving augers inside the drum, which reduces maintenance.

* Instead, we use **Spiral Flights** welded to the inner wall of the drum.

* As the drum rotates, these spirals act like an Archimedes screw, naturally pushing the solids forward.

* This is a gentle transport method that does not break up the solids, ensuring better capture.

* The solids exit the drum and fall into a **Screenings Compactor** or a dumpster.

## Section 4: Applications & Industries

### **Q13: Why is this used in Industrial Wastewater Treatment?**

Industrial streams are often highly variable.

* **Paper & Pulp:** For **Fiber Recovery**. The screen captures valuable pulp fibers.

* **Food Processing:** Removing vegetable skins, seeds, and scraps. The internal feed prevents large items from bypassing the screen.

* **Slaughterhouses:** While external screens are common here, Internal Drum Screens are used for polishing the effluent after the primary screen to remove fine hairs and fats before the **Biological Treatment** stage.

### **Q14: Can it handle grit and sand?**

The Internal Drum Screen is designed for organic solids and trash.

* While it *can* handle some grit, heavy loads of sand can cause premature wear on the perforated plate and the support wheels.

* **Recommendation:** For high-grit applications (like road runoff), we recommend installing a Grit Chamber or Hydrocyclone *before* the fine screen.

### **Q15: Is it suitable for "Scum" removal?**

Yes. Because the water enters the center, floating scum is trapped inside the drum just like heavy solids. The spiral flights effectively move floating scum to the discharge, making it an excellent **Scum Removal** device.

## Section 5: Maintenance & Troubleshooting

### **Q16: What are the maintenance requirements?**

The DAGYEE Internal Drum Screen is designed for **Continuous Operation** with minimal downtime.

1. **Spray Nozzles:** Check periodically for clogging. Our nozzles are removable for cleaning.

2. **Support Wheels:** These are the main wear parts. They support the drum's weight. Depending on usage, they typically need replacement every 2–3 years.

3. **Drive Chain/Gear:** Lubricate the drive mechanism regularly.

4. **Seals:** Inspect the inlet seal (where the stationary pipe enters the rotating drum) to ensure no raw water is leaking (bypassing) the screen.

### **Q17: Troubleshooting: Water is bypassing the screen (leaking at the front).**

This usually indicates a worn **Inlet Seal**.

* The interface between the fixed inlet pipe and the rotating drum is sealed with a heavy-duty rubber or neoprene seal.

* If this wears out, raw water can short-circuit.

* DAGYEE designs this seal to be easily bolted on/off for quick replacement without dismantling the drum.

### **Q18: Troubleshooting: The screen is rotating but solids are not discharging.**

* **Cause 1:** The internal flights are clogged with sticky grease. *Solution: Increase hot water wash pressure.*

* **Cause 2:** The drum speed is too slow. *Solution: Increase speed via VFD.*

* **Cause 3:** The solids are too fluidized (too much water). *Solution: The screen might be hydraulically overloaded.*

### **Q19: Does the system require a lot of power?**

No. This is a **Low Energy Consumption** device.

* Because the drum is balanced and rotates slowly (typically 4 – 8 RPM), the motor required is small.

* A unit treating 200 m³/hr often runs on a **0.75 kW or 1.1 kW** motor.

* The primary energy consumer is the feed pump (if not gravity fed) and the wash water pump.

## Section 6: Commercial, Logistics & Purchasing

### **Q20: What information does DAGYEE need for a proposal?**

To engineer the perfect screen, we need:

1. **Application:** (Municipal Sewage, Paper Mill, etc.).

2. **Peak Flow Rate:** (m³/hr or GPM).

3. **TSS Load:** (Total Suspended Solids mg/L).

4. **Desired Slot/Hole Size:** (e.g., 1mm, 2mm).

5. **Channel Dimensions:** (Width and Depth).

6. **Material Preference:** (SS304 or SS316).

7. **Discharge Requirement:** (Do you need a compactor included?).

### **Q21: Can DAGYEE provide a complete screening system?**

Yes. We often supply the **Internal Drum Screen** as part of a package including:

* **Screenings Washer/Compactor:** To wash organics off the trash and dewater it further.

* **Shaftless Screw Conveyor:** To transport the waste to a dumpster.

* **Control Panel (PLC):** To integrate the screen, spray bar, and compactor into one automated logic system.

### **Q22: How is the unit shipped?**

* **Small/Medium Units:** Shipped fully assembled. You simply place it in the channel/tank, connect piping, and wire the motor.

* **Large Units:** May be shipped with the stand detached to fit in a container.

* DAGYEE provides detailed **Installation Drawings** and video support.

### **Q23: Why choose DAGYEE over a local trading company?**

1. **Direct Manufacturer:** You get factory-direct pricing and faster communication.

2. **Custom Engineering:** We modify the machine to fit your civil works, saving you expensive construction costs.

3. **Quality Assurance:** We use laser-cutting for our perforated plates to ensure perfectly round holes with no burrs, maximizing the **Filtration Efficiency**.

4. **Spare Parts:** We stock standard wheels, seals, and nozzles for global dispatch.

## Summary: The DAGYEE Advantage

The **Internal Drum Screen** is the guardian of your wastewater treatment plant. Whether you are protecting sensitive MBR membranes or recovering valuable industrial fibers, the performance of the screen dictates the efficiency of the entire plant.

At **DAGYEE**, we combine robust stainless steel construction with precise **Perforated Plate** technology to deliver screens that offer high capture rates and low maintenance. Our **Customizable** approach ensures that you don't just get a screen; you get a solution that fits your flow, your space, and your budget.

### **Ready to Upgrade Your Headworks?**

Don't let solids damage your downstream pumps and membranes. Get a screen engineered for superior separation.

**Contact DAGYEE today for a technical consultation, dimensional drawings, and a competitive proposal.**