Browsing by Author "Wu, Shubiao"

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    Evaluation of slow pyrolyzedwood and rice husks biochar for adsorption of ammonium nitrogen from piggery manure anaerobic digestate slurry
    (Science of the Total Environment,, 2015) Kizito, Simon; Wu, Shubiao; Kirui, W. Kipkemoi; Lei, Ming; Lua, Qimin; Baha, Hamidou; Donga, Renjie
    Due to its high adsorption capacity, the use of biochar to capture excess nutrients fromwastewater has become a central focus in environmental remediation studies. In this study, its potential use in adsorption and removal of ammonium in piggery manure anaerobic digestate slurry was investigated. The adsorbed amount of NH4 +-N (mg·g−1) and removal percentage as a function of adsorbent mass in solution, adsorbent particle size, NH4 +-N concentration in the effluent, contact time, pHand temperaturewere quantified in batch equilibriumand kinetics experiments. The maximum NH4 +-N adsorption from slurry at 1400 mg N·L−1 was 44.64 ± 0.602 mg·g−1 and 39.8 ± 0.54 mg·g−1 for wood and rice husk biochar, respectively. For both biochars, adsorption increased with increase in contact time, temperature, pH and NH4 +-N concentration but it decreased with increase in biochar particle size. Furthermore, the sorption process was endothermic and followed Langmuir (R2 = 0.995 and 0.998) and Pseudo-second order kinetic models (R2 = 0.998 and 0.999). Based on the removal amounts, we concluded that rice husk and wood biochar have potential to adsorb NH4 +-N from piggery manure anaerobic digestate slurry, and thus can be used as nutrient filters prior to discharge into water streams.
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    Phosphate removal from aqueous solution using iron oxides: adsorption, desorption and regeneration characteristics
    (Journal of Colloid and Interface Science, 2018) Ajmal, Zeeshan; Muhmood, Atif; Usman, Muhammad; Kizito, Simon; Lu, Jiaxin; Dong, Renjie; Wu, Shubiao
    Dynamics of phosphate (PO4 3-) adsorption, desorption and regeneration characteristics of three lab-synthesized iron oxides, ferrihydrite (F), goethite (G), and magnetite (M) were evaluated in this study. Batch experiments were conducted to evaluate the impact of several adsorption parameters including adsorbent dosage, reaction time, temperature, pH, and ionic strength. The results showed that PO4 3- adsorption increased with reaction time and temperature while it decreased with an increase in solution pH. Adsorption isotherm data exhibited good agreement with the Freundlich and Langmuir model with maximum monolayer adsorption capacities of 66.6 mg·g-1 (F), 57.8 mg·g-1 (M), and 50.5 mg·g-1 (G). h u u Δ < ΔH > ΔS > demonstrating that PO4 3- adsorption onto tested minerals is endothermic, spontaneous, and disordered. The PO4 3- removal mostly occurred via electrostatic attraction between the sorbate and sorbent surfaces. Moreover, the PO4 3- sorption was reversible and could be desorbed at varying rates in both neutral and alkaline environments. The good desorption capacity has practical benefits for potential regeneration and re-use of the saturated particles in wastewater treatment systems.
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    Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand
    (Sustainability, 2019) Kizito, Simon; Luo, Hongzhen; Lu, Jiaxin; Bah, Hamidou; Dong, Renjie; Wu, Shubiao
    Recycling and value-added utilization of agricultural residues through combining technologies such as anaerobic digestion and pyrolysis could double the recoverable energy, close the nutrient recycle loop, and ensure cleaner agricultural production. This study assessed the beneficial application of biochar to soil to recycle digestate nutrients, improve soil quality, and reduce conventional chemical fertilizer. The addition of digestate-enriched biochar improved soil quality as it provided higher soil organic matter (232%–514%) and macronutrients (110%–230%) as opposed to the unenriched biochar and control treatments. Maize grown in soil amended with digestate-enriched biochar showed a significantly higher biomass yield compared to the control and non-enriched biochar treatments but was slightly lower than yields from chemical fertilizer treatments. The slightly lower yield (20%–25%) achieved from digestate-enriched biochar was attributed to slower mineralization and release of the adsorbed nutrients in the short term. However, digestate-enriched biochar could in the long term become more beneficial in sustaining soil fertility through maintaining high soil organic matter and the gradual release of micronutrients compared to conventional chemical fertilizer. Positive e ects on soil micronutrients, macronutrients, organic matter, and biomass yield indicates that enriched biochar could partly replace chemical fertilizers and promote organic farming in a circular economy concept.