Appropriate technology for soil remediation in tropical low-income countries - a pilot scale test of three different amendments for accelerated biodegradation of diesel fuel in Ultisol

Figures & data

Table 1. Physical and chemical characterization of the soil at the experimental site

	Topsoil	Subsoil
pH (H2O)	5.3	4.8
Organic Matter (%)	6.8	3.5
CEC (meq 100 g^−1)	9.3	10.00
Soil texture
Clay (%)	46.4	46.0
Silt (%)	29.6	23.6
Sand (%)	24.0	30.4
Chemical composition
N (total %)	0.14	-
P (Mehlich III, ppm)	22	13
K (available, ppm)	187	65
Ca (ppm)	843	634
Mg (ppm)	194	227
Na (ppm)	26	30
S (total, ppm)	19	18
Fe (ppm)	82	37
Cu (ppm)	1.1	0.8
Zn (ppm)	2.9	1.5
Mn (ppm)	132	121
B (ppm)	0.6	0.3

Figure 1. The interior of the experimental station with its 24 concrete compartments

Table 2. Treatment levels of the three amendments

	Description	Amounts added (kg^−1 soil dw)
1 WL	Whey low	0.6 mL
2 WH	Whey high	6 mL
3 PAL	Pyroligneous acid low + lime	0.1 mL
4 PAH	Pyroligneous acid high + lime	1 mL
5 CL	Compost tea low	2.5 mL
6 CTH	Compost tea high	25.3 mL
7 C	Control	-

Figure 2. Effect of the different amendments on the degradation of the total diesel range hydrocarbons. The X-axis indicate the percentage of the diesel that remained in the soil. The white rhombi indicates statistical significance (based on the data before normalisation) and the errors bars indicate standard deviation of the normalized data. The abbreviations reflect the type of amendments and treatment level (high/low) according to the following; C = Control, CTH = Compost tea high, CTL = Compost tea low, PAH Pyroligneous acid high, PAL = Pyroligneous acid low, WH = Whey high, WL = Whey low