Field experiments were conducted to study the effect of sewage sludge application on the heavy metal content in soils and grasses. The sewage sludge was obtained from Northern Shenyang Wastewater Treatment Plant, China, and applied at 0, 15, 30, 60, 120 and 150tha(-1). Native grasses Zoysia japonica and Poa annua were chosen as experimental plants. The experimental results showed that nutrient content of the soil, especially organic matter, was increased after sewage sludge application. The grass biomass was increased and the grass growing season was longer. Heavy metal concentrations in the soil also increased; however, the Zn content did not exceed the stringent Chinese environmental quality standard for soil. Pb and Cu did not exceed the standard for B grade soil, but Cd concentration in soil amended by sewage sludge has exceeded the B grade standard. Therefore, it is suggested that the sewage sludge produced from the wastewater treatment plant should not be applied to farmland, for which B grade soil or better is required. The sludge is suitable for application to forestry and grasslands or nurseries where food chain contamination with cadmium is not a concern.
"Agriculture has become an alternative destination for the sizeable quantities of sewage sludge (SS) generated , due to the presence of plant nutrients in organic waste (Melo et al., 2007; Wang et al., 2008). However, its use can also harm the soil-plant system, due principally to an imbalance in nutrients in this waste (Bertoncini et al., 2004). "
[Show abstract][Hide abstract] ABSTRACT: Sewage sludge (SS) has been widely used as organic fertilizer. However, its continuous use can cause imbalances in soil fertility as well as soil-water-plant system contamination. The study aimed to evaluate possible improvements in the chemical and microbiological characteristics of domestic SS, with low heavy metal contents and pathogens, through the composting process. Two composting piles were set up, based on an initial C/N ratio of 30:1, with successive layers of tree pruning waste and SS. The aeration of piles was performed by mechanical turnover when the temperature rose above 65 ºC. The piles were irrigated when the water content was less than 50 %. Composting was conducted for 120 days. Temperature, moisture
Scientia Agricola 09/2015; 72(5):432-439. DOI:10.1590/0103-9016-2014-0341 · 0.81 Impact Factor
"Researchers applied 0, 15, 30, 60, 120, and 150 t ha " 1 SS concentrations in native grasses, zoysia grass (Zoysia japonica) and annual bluegrass (Poa annua). According to their study, the nutrient content of the soil, especially the organic matter, was increased after the SS application (Wang et al., 2008). Moreover, while some heavy metals, such as Pb, Cd, As, and Hg, were determined at high concentrations in some plants, but their values were reported at the permitted limits in the soil (Singh and Kumar, 2006; Karavin et al.,2014), some of them, such as Cu, Ni, Cr and Co, were measured at more than the normal level, or at the limit (Karavin et al., 2014). "
[Show abstract][Hide abstract] ABSTRACT: This study was conducted to determine the effects of sewage sludge (SS) used as fertilizer at different concentrations [Control, 20 kg ha–1 nitrogen (N), 30 ton ha–1 SS (S1), 60 ton ha–1 SS (S2) and 90 ton ha–1 SS (S3), 20 kg ha–1 N + 30 ton ha-1 SS (N + S1), 20 kg ha–1 N + 60 ton ha–1 SS (N + S2) and 20 kg ha–1 N + 90 ton ha–1 SS (N + S3)] on common vetch yields and chemical features. For this purpose, an increasing level of SS was applied to the soil samples. The residuals of some heavy metal (Hg, Cr, Fe, Ni, Zn, Mn, Cd, Pb, Cu, Co, and Se) and macro element (K, Ca, Na, Mg, C, and S) concentrations were measured in leafs, seeds and soils. According to the results of this study, SS, when applied to soil in increasing amounts, raised the mineral matter contents of the plants, which favorably affected plant growth. Accordingly, it affected the herbage yield, increasing the yield in parallel with the increasing SS concentrations. Applying N with the SS positively influenced the heavy metal contents on leafs and seeds of common vetch and residue in the soil. Besides, the heavy metal contents were found at below critical levels in the soil, leaf and seeds. Therefore, SS application as fertilizer used in appropriate concentrations did not pollute the soil very much, but did lead to an increase in plant products.
Legume Research 08/2015; 38(4):488-495. DOI:10.5958/0976-0571.2015.00133.2 · 0.15 Impact Factor
"The role of sewage sludge utilization on agricultural lands as a fertilizer is known to result in the recycling of valuable components, including organic matter , N, P, K and micronutrients (Singh and Agrawal, 2007). However, high concentrations of heavy metals (HMs), such as Zn, Cu, Cr, Ni, Cd, and high amounts of pathogens in sewage sludge led to concerns regarding soil and groundwater pollution (Gascó et al., 2005; Wang et al., 2008). In addition, high concentrations of N and P in sewage sludge have adverse environmental effects (Sumner, 2000). "
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