Ashes (residues), coal

Endpoint summary

Additional information

The environmental toxicity profile of ash (residues), coal has been well defined. Short term and long term tests with species of 3 trophic levels are available for different types of ashes (residues), coal.

The ashes (residues), coal with higher content of free lime proved to be harmful to green algae with EL50 values for the growth rate of 30 mg/L. No toxicity was observed in any of the tests with the other ashes (residues), coal. In these cases the NOEL of green algae is greater than 100 mg/L. Short term effects of the substance towards fish and daphnia were found to be in the same range providing NOEL values of greater than 100 mg/L.

Additionally, the long term toxicity tests to aquatic invertebrates indicated that the ashes (residues), coal with higher content of free lime did not affect the growth or reproduction of Daphnia magna when exposed to a WAF prepared at a loading rate of 2.2 mg/L (NOEL) for 21 days. Moreover the ashes (residues), coal without higher content of free lime also did not affect reproduction or survival of Daphnia magna at a WAF prepared at a loading rate of 100 mg/L after 21 days of exposure.

The ashes (residues), coal with higher content of free lime indicated slightly harmful effects to aquatic organisms whereas other ashes (residues), coal are not harmful to aquatic organisms. The heavy metal content of the tested substance had no influence on toxic effects on aquatic organisms. Measured data from the aquatic tests show that the bioavailability of the heavy metals is low. Two aqueous solutions prepared from ashes (residues), coal with higher content of free lime and the control solutions were further analysed for macro and trace elements. The concentration of trace metals in the WAF´s were found to be very low. Most elements, which are known to have negative effects on health and environment were either not detected or found in lower concentrations compared to the controls. The concentrations of all elements measured were found in the range of µg/L or below detection limit (seeTable 24). Even ashes with a higher content on Cu (249 mg/kg) and Ni (351 mg/kg) showed no toxicity in all aquatic tests, and these results reveal that metals are mainly in insoluble forms and not bioavailable under normal environmental conditions.

 

Table 24: Concentration of the water soluble components in the WAF´s [mg/L]  

sample	1	2	Medium
code	09-011	09-012
leaching	100 mg/L	100 mg/L	0 mg/L
duration	48 h	48 h
macro el.	µg/L	µg/L	µg/L
Al	1800	590	50
Ca	21000	8900	8800
Cl	48000	11000	30000
Fe	23	66	29
K	1500	1200	1700
Mg	4400	770	3900
Na	14000	15000	14000
P	430	72	470
S	4900	1900	2600
S04	15000	5400	7200
Si	1300	800	< 200
Ti	2,7	2,6	< 2
Trace el.	µg/L	µg/L	µg/L
As	< 5,0	< 5,0	< 5,0
B	120	85	61
Ba	120	12	< 10
Be	< 2	< 2	< 2
Br	< 50	< 50	50
Cd	< 0,1	< 0,8	< 0,1
Co	< 2	< 2	< 2
Cr	< 2	< 2	< 2
Cu	< 2	< 2	10
F	< 100	< 100	< 100
Hg	< 0,03	< 0,03	< 0,03
Mn	15	85	180
Mo	< 5	13	< 5
Ni	< 5	< 5	< 5
Pb	< 5	< 5	< 5
Sb	< 5	< 5	< 5
Se	< 5	< 5	< 5
Sn	< 15	< 15	< 15
Sr	120	30	3,2
Te	< 15	< 15	< 15
TI	< 1	< 1	1,2
V	< 4	4	< 4
W	< 20	< 20	< 20
Zn	2,3	3,2	9,2

Several studies on respiration inhibition effects in activated sewage sludge are available for ashes (residues), coal. The NOEL is greater than 100 mg/L (WAF). There is no toxicity in the range of water solubility of ashes (residues), coal and the inhibition of the degradation activity of activated sludge is also not anticipated.