| Phosphorus discharge from wastewater including livestock wastewater(e.g.,swine and cattle wastewater)is threatening environment wordwidely.Meanwhile,livestock wastewater appraises as vein of resources,of which phosphorus can be re-used in agriculture as a resource of nutrient.Therefore,phosphorus removal and recovery from wastewater such as livestock wastewater could practically alleviate the phosphorus resource predicament,and various technologies including low-cost adsorption technique could realize the removal and recovery of phosphorus.Especially,organic phosphonate,as an important type of phosphorus in wastewater,the removal and recovery of phosphonate has rarely been studied in this regard.Therefore,this study investigated novel adsorbents for the removal of phosphonate(NTMP;as selected organic phosphorous species),the desorption and reusability as well as the removal mechanisms,while real livestock phosphorus removal was also investigated.Firstly,a novel zirconium-lanthanum modified magnetite adsorbent(ZrLa@Fe3O4)was developed for the removal and recovery of nitrilotrismethylenephosphonate(NTMP)from wastewater.The NTMP adsorption capacity and desorption efficiency were investigated under various conditions,while the characterization of the novel adsorbent was also performed.The results showed that 99%NTMP removal efficiency was achieved using Zr-La@Fe3O4 adsorbent.In addition,using different initial concentrations of NTMP,the highest adsorption capacities obtained at equilibrium stage were 16 mg/g to 77 mg/g.Isotherm model of NTMP adsorption on Zr-La@Fe3O4 was well illustrated by the Langmuir model(R2=0.994),while the pseudo-second-order model(R2=0.893)was well demonstrated in the kinetics study.Besides,acid pH conditions(3,4,5,6)could promoted the NTMP adsorption.Nevertheless,the NTMP adsorption capacity was decreased with the increase of adsorbent dosage.A higher desorption efficiency was found with 1 mol/L NaOH solution,achieving 38.53%DE of NTMP,and then decreased with the increasing number of cycles in the reusability experiment.This novel adsorbent demonstrated potential for removal and recovery of NTMP and to become a promising technology for further research.Secondly,the desorption and reusability of phosphonate including nitrilotrismethylenephosphonate,which is important for adsorption process,has never been thoroughly explored.For this purpose,desorption efficiency,reusability and kinetic desorption study of nitrilotrismethylenephosphonate were systematically investigated in this study.The desorption mechanism was studied by XPS(X-Ray Photoelectron Spectroscopy)analysis.The results showed that both the pseudo second order and pseudo first order were fitted well for nitrilotrismethylenephosphonate desorption.The decreased of organic phosphorus(OP)presented to new findings for conversion of nitrilotrismethylenephosphonate into inorganic ortho-phosphate phosphorus(IP)during Kinetic and reusability(1.5 mol/L NaOH)which was exhibited to lower desorption efficiency of nitrilotrismethylenephosphonate.The highest desorption efficiency of 92.7%and 114.7%were achieved with 3 mol/L NaOH and 0.30 mol/L NaOH+NaCl solution.The reusability was successful in five cycles by 96.1%and 83.4%with 3 mol/L NaOH and 0.30 mol/L NaOH+NaCl.Comparably,higher total phosphorus(TP)100%efficiency is involved during nitrilotrismethylenephosphonate reusability.The 100%sustained removal efficiency of nitrilotrismethylenephosphonate made the zirconium-lanthanum modified magnetite as a promising aspirant for wastewater treatment.The XPS analysis suggested inner-sphere complexation mechanism.Overall,zirconium-lanthanum modified magnetite has a potential implementation for nitrilotrismethylenephosphonate desorption in practices.Thirdly,the influence of adsorbent dosage,pH,hydrodynamic and COD on phosphorus removal and recovery from real livestock wastewater were investigated.Moreover,the kinetics mechanism and the reusability implementation were examined for phosphorus removal.The results showed that organic phosphorus(OP)removal efficiency was higher by 99.9%(cattle wastewater)and 99.3%(swine wastewater)maintained at higher adsorbent dosages(0.06 g).The higher removal efficiency of 97.8%(IP),98.3%(TP),and 99.4%(OP)was achieved at 8 for cattle wastewater and 98%(IP),99.3%(TP),and 99.5%at pH 7 for swine wastewater.The hydrodynamically phosphorus removal efficiency was higher at increased stirring speed,and the intraparticle diffusion model fitted well with high correlation coefficients(e.g.,R2=0.941 and 0.974 for TP from the cattle and swine wastewater,respectively).The higher adsorption capacity for IP(287 mg/g),and TP(295.6 mg/g)was observed from the swine wastewater.IP,TP,and OP removal efficiency were higher when COD concentration decreased with increased reaction time.The maximum desorption efficiencies of 78.9%(IP),79.9%(TP),and 85.2%(OP)were reached for cattle wastewater,while 70.9%-91.5%(IP),75.3%-93.7%(TP)and 89.8%-98.3%(OP)obtained for swine wastewater during the reusability experiment.The lower desorption efficiency from the cattle wastewater might be occurred due to precipitation of CaCO3 and a high amount of total suspended solids.Overall,the Zr-La@Fe3O4 magnetite adsorbent is effective in practical applications.Overall,scientifically this thesis study reffering to the adsorption and desorption mechanism study of organic phosphorus wirh novel adsorbent(Zr-La@Fe3O4).Excellent removal of NTMP and adsorption capacity was generally obtained.The innovative results of NTMP conversion into IP achieved through the decreasing of organic phosphorus(OP)which indicated to lower desorption of NTMP.Further,the adsorbent amount is effective for treatment of livestock wastewater as relatively low cost of dosage. |
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