Evaluating the feasibility of muck from slurry shield tunnels as a growth medium for landscaping

Figures & data

Figure 1. Processes to produce MSST.

Table 1. Physical properties and particle size composition of MSST

Wet density (g/cm^3)	Dry Density (g/cm^3)	Water content (%)	Specific gravity	Void ratio	Saturation (%)	Liquid limit (%)	Plastic limit (%)	Plasticity index	Liquidity index
1.60	0.96	67.7	2.68	1.81	100.5	26.28	61.71	35.42	1.17
Particle content less than a certain particle size (mm)/%
0.075	0.01	0.005	0.002	0.001	Uniformity coefficient (Cu) = 10.67
100%	42.14%	20.89%	13.96%	7.20%	Coefficient of curvature(Cc) = 2.04

Table 2. Chemical and hydrophysical characteristics of the MSST

Index	MSST	LGS	GB15618-2008
pH	7.21	8.05	< 9.0
Total nitrogen (g/kg)	0.441	0.620	-
Total phosphorus (g/kg)	0.267	0.370	-
Total potassium (g/kg)	2.449	10.70	-
Alkali hydrolyzed nitrogen content (mg/kg)	83.463	24.64	-
Available phosphorus content (mg/kg)	60.653	7.85	-
Available potassium content (mg/kg)	199.094	86.92	-
Organic Matter (g/kg)	10.400	2.35	-
Ca (%)	3.28	-	-
Mg (%)	5.23	-	-
Al (%)	8.21	-	-
Zn (mg/kg)	3.21	118.5	< 300
Cr (mg/kg)	52.31	91.4	< 350
Cu (mg/kg)	162.14	30.34	< 200
Cd (μg/kg)	7.21	0.45	< 350
Hg (μg/kg)	0.73	0.20	< 1.0
Pb (μg/kg)	33.21	57.74	< 80

Figure 2. Result of SEM image and XRD image: (a) SEM image; (b) XRD image.

Figure 3. Pot experiment process.

Figure 4. Chlorophyll content of ryegrass in tillering stage and florescence stage.

Figure 5. Root characteristics and root activity of ryegrass in tillering stage and florescence stage: (a) total root length; (b) number of root tips; (c) total root surface area; (d) root activity.

Table 3. Physicochemical parameters of the mixtures

	After curing			Florescence stage
Sample	LGS	MSST	MSSTF	LGS	MSST	MSSTF	CJT 340–2011
Organic matter (g/kg)	2.35	10.40	11.51	2.03	9.02	10.05	-
Total nitrogen (g/kg)	0.62	0.44	0.45	0.58	0.42	0.42	-
Total potassium (g/kg)	10.70	2.45	3.01	12.88	12.90	14.97	-
Total phosphorus (g/kg)	0.37	0.27	0.27	0.72	0.52	0.53	-
Alkali hydrolyzed nitrogen (mg/kg)	24.64	83.46	83.46	60.21	80.00	80.00	≥ 40
Available phosphorus (mg/kg)	7.85	60.65	65.33	24.37	16.32	17.57	≥ 8
Available potassium (mg/kg)	86.92	199.09	231.05	123.5	120.12	143.24	-
pH	8.05	7.21	7.75	7.03	7.01	7.20	5.5 ~ 8.3

Data availability statement

Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. https://tmxy.csuft.edu.cn/szdw/fjslm/202104/t20210419_110140.html.