Hamed Fathi (email is hamed_fathi_dokht at yahoo.com) is a Ph.D. student in Gorgan University of Agricultural Sciences and Natural Resources (Iran), working on a thesis entited The Effect of sewage sledge and their bio-char as mulch and top-soil incorporated on some soil attributes, lead adsorption and desorption Isotherms potassium uptake and plant(soybean) growth in a loss soil with high specific surface area in a temperate climate. He is looking for a 6 - 8 month sabbatical host at an institute starting September 2015 (he has funding for this research). To see a C.V., please click here.
Says Mr. Fathi "This research is a bi-annual field experiment for growing soybean with bio-char treatments from sewage sludge sources as mulching and soil incorporated which were combined with nitrogen and potassium fertilizers at various rates. The first year experiment was already carried out with promising results manifested in greater soybean production. Sewage sludge is a source of pathogens if it is used for agricultural purposes without proper treatments. I addition to carbon sequestration benefits, bio-char produced at high temperatures destroys pathogens. Charcoal wells are widespread throughout many countries in Middle East (Like Iran) which can be used for bio-char production without modifications. Same plots are used for soybean production in second year."
This is a short write up on my work
1-Sewage sledge was selected as the raw material to produce biochars. Biochars were produced via paralyzing the biomass at various temperatures under O2–limited conditions. Dried sewage sledge were collected from the north of Iran, broken into small pieces, and then washed with tap water three times to remove dust. After oven drying at 80°C for 2 days, the sewage sledge were milled into powder and passed through a 2-mm sieve. The sewage sledge powder was paralyzed in a closed ceramic pot under O2–limited conditions at 300°C for 3 h, and (650°C) for 3 h.
2-The experimental design was a randomized complete block with three replicates. A field experiment was set up to study the effect of sewage sledge biochar on soybean growth. Five amendment treatments included (i) a control (no Sewage sledge or biochar application); (ii) Sewage sledge application (25 Mg ha-1 dry wt. Mulch application of sewage sledge); (iii) biochar application (25 Mg ha-1 dry wt. mulch application of sewage sledge biochar) (iv) Sewage sledge application (25 Mg ha-1 dry wt. Topsoil incorporated application of sewage sledge) and (v) Sewage sledge application (25 Mg ha-1 dry wt. Topsoil incorporated application of sewage sledge biochar)
3- Batch adsorption and desorption experiments
Air-dried soil samples (200 g) were placed in polythene cups and biochar was added at 0%, 3% or 5%. The soil and biochar were mixed thoroughly and then wetted with deionized water to 70% of field water holding capacity of the soil. All cups were covered with a plastic lid, and a small hole made to allow gas exchange but to minimize moisture loss, and then incubated at a constant 25°C. The cups were weighed every 5 days, with water added to maintain constant moisture content throughout the incubation period. After 30 days of incubation, the soil samples were removed from the cups. Then, 5 g of soil samples were air-dried and ground to pass a 300-mesh sieve for zeta potential determination. Other parts of samples were air-dried and ground to a pass 60-mesh sieve for adsorption experiments.
A stock solution containing 0.1 M Pb(NO3)2 was prepared using reagent-grade Pb(NO3)2. A 1000-mL aliquot of 1 M NaNO3 solution and appropriate quantities of 0.1 M Pb(NO3)2 solution and deionized water were added into 1000-mL volumetric flasks to obtain mixed solution with 0.001 M NaNO3 and various concentrations of Pb(NO3)2 (0.1, 0.25, 0.5, 1.0, 1.5 or 2.0 mM for concentration effect experiments and 2.0 mM for pH effect experiments). NaNO3 (0.001 M) was used as the supporting electrolyte to maintain the ionic strength in the adsorption experiments. The pH Solution was adjusted to the target values with either HNO3 or NaOH