A dried sludge product resulting from the treatment process of domestic wastewater. The exact processes followed for the production of the dried sludge are: Preliminary + secondary treatment of the wastewater stream, thickening, dehydration and drying of the excess sludge.

Particle size distribution (Granulometry)

Link to relevant study record(s)

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8 March 2021 – 16 March 2021

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline required

Principles of method if other than guideline:

The grain size distribution of the substance was determined by cascade sieving.

GLP compliance:

no

Type of method:

sieving

Type of distribution:

other: Grain size distribution

Percentile:

other: 0.35%

Mean:

> 4 mm

St. dev.:

0.1

Percentile:

other: 42.42%

Mean:

> 2 - < 4 mm

St. dev.:

0.1

Percentile:

other: 48.06%

Mean:

> 1 - < 2 mm

St. dev.:

0.1

Percentile:

other: 8.39%

Mean:

> 0.5 - < 1 mm

St. dev.:

0.1

Percentile:

other: 0.57%

Mean:

> 150 - < 500 µm

St. dev.:

0.1

Percentile:

other: 0.06%

Mean:

> 100 - < 150 µm

St. dev.:

0.1

Percentile:

other: 0.12%

Mean:

> 50 - < 100 µm

St. dev.:

0.1

Percentile:

other: 0.03%

Mean:

< 50 µm

St. dev.:

0.1

The results obtained for the grain size (d) are as follows (averages of 3 measurements):

Grain size	%
d >4mm	0.35 ± 0.06
2 < d <4mm	42.42 ± 1.54
1 < d <2mm	48.06 ± 1.62
0.5 < d <1mm	8.39 ± 0.39
150μm < d < 0.5mm	0.57 ± 0.16
100μm < d < 150μm	0.06 ± 0.04
50μm < d < 100μm	0.12 ± 0.08
d < 50μm	0.03 ± 0.01

 

Conclusions:

The grain size of the material examined was centred around 2 mm with very small amounts > 4 mm and <0.5 mm.

Executive summary:

Dried waste sludge from a biological civic effluent treatment utility was examined to ascertain its grain size distribution.

 

The method used was sieving through a cascade of graduated sieves of precision ± 0.1mm. A total of about 1.5 kg of material was examined in three tests and the average results obtained for the grain size (d) are as follows:

 

The specific methods and results obtained are as follows:

Grain size	%
d >4mm	0.35 ± 0.06
2 < d <4mm	42.42 ± 1.54
1 < d <2mm	48.06 ± 1.62
0.5 < d <1mm	8.39 ± 0.39
150μm < d < 0.5mm	0.57 ± 0.16
100μm < d < 150μm	0.06 ± 0.04
50μm < d < 100μm	0.12 ± 0.08
d < 50μm	0.03 ± 0.01

Description of key information

The grain size distribution of the substance was determined by sieving through a cascade of graduated sieves.

Additional information

The specific methods and results obtained are as follows:

Grain size	%
d >4mm	0.35 ± 0.06
2 < d <4mm	42.42 ± 1.54
1 < d <2mm	48.06 ± 1.62
0.5 < d <1mm	8.39 ± 0.39
150μm < d < 0.5mm	0.57 ± 0.16
100μm < d < 150μm	0.06 ± 0.04
50μm < d < 100μm	0.12 ± 0.08
d < 50μm	0.03 ± 0.01