1,720,995 research outputs found
Trattamento ecocompatibile di effluenti zootecnici mediante fitodepurazione a flusso subsuperficiale
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Reuse of liquid, dewatered and composted sewage sludge on agricultural land: effects of long-term applications on soil and crop.
No full textTo evaluate the effects of repeated sewage sludge applications in comparison to mineral fertilisers on a winter wheat - maize - sugar beet rotation, a field experiment on a silty-loam soil, in the eastern Po Valley (Italy), was carried out since 1988. Municipal-industrial wastewater sludge as anaerobically-digested, belt filtered (dewatered), and composted with wheat straw, has been applied at 5 and 10 Mg DM ha-1yr-1..
Biosolids gave crop yields similar to the highest mineral fertiliser dressing. However, with the higher rate of liquid and dewatered sludges, excessive N supply was harmful, leading to wheat lodging and poor quality of sugar beet and wheat crops. From this standpoint compost use was safer.
Biosolids increased organic matter (OM), total N, and available P in the soil and reduced soil alkalinity, with more evident effects at the highest rate. Compost caused the most pronounced OM topsoil accumulation. Significant accumulations of total Zn and Cu were detected in amended topsoil, but no other heavy metals (Cd, Cr, Ni, Pb), whose total concentration remained well below the hazard limits. Biosolid applications significantly increased the content of N, P, Zn, and Cu in wheat grain, N and Cu in sugar beet roots, and only Cu in maize grain.
Although, the application of biosolids brought about notable benefits to soil fertility, it is associated with possible negative effects on water quality due to increased P availability and on soil ecology due to Zn accumulation
Accumulation of copper and zinc from liquid manure in agricultural soils and crop plants
No full textBiomass production and nutrient uptake of cattail (Typha latifolia) in a h-SSF system treating dairy wastewaters in northern Italy.
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Treating dairy parlor wastewater using subsurface-flow constructed wetlands
No full textTwo horizontal subsurface flow reed beds to treat parlor effluent as well as domestic sewage, each 75 m(2), were built in 1999. The goal of the project is to verify the efficiency of this treatment system to reduce the polluting load of parlor effluent, which are more polluted than domestic sewage. Throughout the first year of the trial the two wetlands operated one after the other in succession and wastewater inflows and outflows were sampled 20 times. Analyses were made for pH, TSS, COD, BOD5, TKN, NH4-N, NO3-N, P, Cu and Zn. The reduction of suspended solids and organic load remained consistently at levels greater than 90%; those of the nutrients N and P were over 40% and 50%, respectively. The monitoring of the heavy metals Cu and Zn made it possible to verify that their load was reduced consequent to deposit in the sediments in moving through the system, while the phenomenon of assimilation by the reeds was shown to be insignificant. Mycorrhizae were found in the roots of the reeds of both wetlands, which indicates a possible strengthening of the assimilation activity of the plants
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