Common Mistakes to Avoid When Selecting Filter Media for Sewage Treatment Plants (STPs)

Why Filter Media Selection Matters in STPs

In Sewage Treatment Plants (STPs), filtration is the final polishing step before discharge or reuse. Choosing the wrong filter media can result in:

• Poor effluent quality

• Increased maintenance costs

• Media clogging and short lifespan

• Regulatory non-compliance

• Reduced plant efficiency

Whether you’re designing a new system or upgrading an existing one, understanding what to avoid is as important as knowing what to select.

Top 7 Mistakes in STP Filter Media Selection (and How to Avoid Them)

1. Using the Same Media for All STPs

Mistake: Assuming one media type fits all STPs.
Why it’s wrong: Raw sewage characteristics vary widely across industries, domestic housing, and hotels. A one-size-fits-all approach leads to underperformance.

✅ Solution: Test raw and treated water. Choose media based on:

• TSS load

• Oil/grease content

• Organic load (BOD/COD)

2. Ignoring Media Uniformity Coefficient (UC)

Mistake: Selecting media with irregular particle sizes or high UC (>1.7).
Why it’s wrong: It causes uneven flow distribution and channeling, leading to poor filtration.

✅ Solution: Choose media with UC between 1.3–1.5, like Starke’s high-purity silica sand or garnet.

3. Wrong Layering Sequence in Multibed Filters

Mistake: Placing finer media above coarser layers.
Why it’s wrong: It reduces filtration depth and clogs upper layers quickly.

✅ Solution: Follow proper sequence:
Top – Anthracite → Middle – Sand/Purozite → Bottom – Garnet → Base – Gravel

4. Using Low-Capacity Carbon for Odor & Organics

Mistake: Using cheap or low-grade carbon.
Why it’s wrong: Fails to adsorb organics and foul odors; frequent replacement needed.

✅ Solution: Use NSF/AWWA-grade coconut shell activated carbon with iodine value >1000 mg/g.

5. Underestimating Backwash Requirements

Mistake: Selecting fine media without considering backwash pressure.
Why it’s wrong: Causes compaction, media cementing, and clogging.

✅ Solution: Select media that supports easy fluidization and schedule backwash every 5–7 days.

6. Selecting Media Without Considering Reusability

Mistake: Using disposable media in high-load STPs.
Why it’s wrong: Frequent replacement leads to operational downtime and higher cost.

✅ Solution: Use media like Purozite, Garnet, and Walnut Shell, which are reusable for 3–5 years with proper cleaning.

7. Skipping Site-Specific Customization

Mistake: Relying only on catalogs or past references.
Why it’s wrong: Every STP has unique flow, contaminants, and footprint constraints.

✅ Solution: Work with a media supplier that offers customized recommendations based on:

• Flow rate

• Bed depth

• Raw/treated water profile

Suggested Media Combinations for Common STP Scenarios

Why Choose Starke Filter Media for STP Applications?

• ✅ Pre-washed, graded & dust-free media

• ✅ AWWA B100 & NSF compliance

• ✅ Bulk and layer-wise customized supply

• ✅ Technical assistance for filter sizing

• ✅ Available in 25 kg bags and 1-ton jumbo bags

Frequently Asked Questions

Q1. Can I reuse filter media after backwashing in STPs?
Yes—especially Garnet, Purozite, and Walnut Shell can be reused for 3–5 years with proper maintenance.

Q2. What is the ideal media size for STPs?
For most STPs, media sizes of 0.6–1.2 mm are ideal. Layering with coarse garnet (0.3–0.6 mm) improves depth filtration.

Q3. Is activated carbon mandatory in STPs?
If the STP is discharging into surface water or reused for landscaping, carbon is highly recommended to control odor, organics, and color.

Q4. Can I use Purozite in place of sand?
Yes. Purozite has better flow rate, less clogging, and longer life than traditional sand.

Planning or upgrading your STP?

Avoid mistakes. Talk to the experts at Starke for customized media supply and system recommendations.

Email: info@starkefiltermedia.com

Website: www.starkefiltermedia.com