what is sludge building?

  • The sludge settlement and compaction index referred as SVI, which measured as the volume of 1g of activated sludge after 30 minutes sedimentation. Normal range of SVI is 50-150.

  • When the SVI reaches 300-400 or above, it indicates a phenomenon called sludge bulking.

Notes :
SV30 = Activated Sludge Precipitationn rate after 30 mins (%)

MLSS : Sludge concentration inn aeration tank (mg/L)


Inflow Factors

  1. Low Temperature
  2. Low SS
  3. Low pH
  4. CNP = 10051Insufficient N and P
  5. Existence of toxic materials (ex: heavy metals).

Environmental Factors

  1. Summer time longer than winter.
  2. Sunny and dry seasons last longer than rainy seasons.

Microorganism causing sludge bulking

Based on investigation result, most of sludge bulking in wastewater treatment plant is caused by filamentous bacteria, among which Type 021N are the most and are counted for 70% in industrial wastewater bulking cases. Meanwhile, Type 1701 and Type 021N are counted for about 40% total number of fungi.


Small and slightly curved without branches; aerobic type, produced in a wide range of conditions, caused for more than half of sewage sludge bulking cases, and also a lot in industrial wastewater cases.

Dosage reference (actual dose need to be adjust according to the test result)

Product NameMethod
GT 8850
1. Add 100-300 mg/L directly in case of emergency.
2. Continues dosage : For average flow rate, add 5-30 mg/L to the aeration tank after dilution 5 times with water and aeration.

Case Study 1 – Pulp and Paper Mill Biological System

Usage of GT8850 – Before vs After


Without adding GT8850, sludge has poor sedimentation ability and overflow of sedimentation tank contains a lot of SS.


After adding GT 8850, sludge sedimentation ability at the back section of aeration tank was greatly improved.

Microscopic Examination of GT8850 Usage

The usage of GT8850 can control filamentous bacteria, improve sludge bulking and increase sludge compactness.

COD and SS Analysis Result – Pulp and Paper Mill Case Study

1. Before Adding Period

Due to the unstable production activity in the upstream, the effluent quality fluctuated greatly. Without adding GT8850 at the initial stage, the effluent was easy to exceed standard with actual on-site operational problem.

2. Add Period

At 18/07/01, start adding GT8850. The effluent quality was gradually getting stable.

3. Abnormal Water Period

Excess production activity in the upstream caused abnormal effluent quality at 18/09/18. After adding more GT8850, the effluent start to gradually recover to reach the discharge standard.

4. Stable Period

Continuous addition of GT8850 can improve COD and SS quality to reach below discharge standard. It shows improvement of sludge activity in aeration tank and effluent quality stability which caused by usage of GT8850..

GT8850 Benefits – Pulp and Paper Mill Case Study

  • Enrich the aerobic tank microbial ecology and improve the ability to remove pollutants
  • Optimize effluent quality
ParameterWithout GT8850Adding GT8850
Average SS32 mg/L10 mg/L (%R 68.8%)
Average COD113 mg/L95 mg/L (%R 15.9%)
  • Reduce biological sludge treatment cost
  • Produced sludge moisture was reduced from 87% to 83% and production of wet sludge was reduced from 1,009 ton to 831 ton/month (reduced 178 ton sludge/month). Therefore, the cost for biological sludge treatment could be effectively reduced.

Case Study 2 – Hair Products Manufacturer Biological System

Comparison of before and after adding GT8850


Without adding GT8850, the sludge activity is poor and has broken sludge in bad condition, causing sedimentation tank contains a lot of SS and turbid.


After adding GT 8850 at the back site of aeration, sludge had great activity and sedimentation ability. Not only SS at outflow significantly reduced, but the efficiency of COD biodegradation also increased.

GT8850 Benefits – Hair Products Manufacturer Case Study

Adding GT8850 will greatly improve sludge physical characteristic and its activity. Further, it will also enrich the aerobic tank microbial ecology and improve microbial ability to remove pollutants.




  • Optimize effluent quality
ParameterWithout GT8850Adding GT8850
Average SS32 mg/L18 mg/L (%R 43.8%)
Average COD171 mg/L75 mg/L (%R 56.1%)