ABSTRACT
Phosphorus is an important element for the plant growth, and it is used as a fertilizer. It is alimited and non-renewable resources in the earth. But when the excessive amount ofphosphorus goes into waterbody, it works as a nutrient for aquatic plants and algae and causes
eutrophication. So, the recovery of the phosphate from water is very important to avoid
eutrophication and recover phosphate to use as fertilizer.
Phosphate recovery using adsorption is a very attractive and effective method. Nowadays
different types of natural bio waste material are used for phosphate recovery. Using biochar
only is not suitable for phosphate adsorption because of the negative surface charge of thebiochar. But metal modified biochar has good phosphate adsorption capacity. Sometime theadsorbed material could not be used as fertilizer because of presence of heavy metal in modifiedadsorbent.
Eggshell decorated biochar exhibits excellent phosphate adsorption capacity than only biochar.
Moreover, calcium is not toxic. That’s why current study was intended to recover the phosphatefrom wastewater using a most convenient procedure and available materials. Bamboo andeggshell were used as an available natural ingredient which was not used for phosphaterecovery before. Since bamboo char is the source of carbon and eggshell as the resource for
CaCO3, would be used as a metal cation which has great affinity for phosphate. So, thecombination of pure biochar with calcite could be a good adsorbent material to recoverphosphate from wastewater. Another objective of this study was to examine the phosphatedesorption using DI water at different temperature and the effectiveness of the phosphateloaded materials as P fertilizer on Japanese mustard spinach cultivation for the sustainable
management of the P adsorbed material.
Bamboo and eggshell adsorbent were prepared for different mixing ratio and temperature (600,700, and 800°C) to find out effective ratio and calcination temperature. To investigate thefeasibility of calcined bamboo and eggshell for phosphate removal, different calcination
temperature, initial concentration, temperature, time, dose rate, pH, and presence of different
ions was examined. Adsorption mechanism was understood by adsorption isotherm,
thermodynamics study, and adsorption kinetics. Morphological changes and characterizationof the adsorbent after calcination and adsorption were identified by the SEM image, EDX
spectra and FTIR analysis. The maximum P adsorption capacity of the BE 1:1 and BE 2:1 wasfound 95.14 mg/g and 98.40 mg/g respectively. For CE, BE 1:1 and BE 2:1 adsorbent, the dataXI

were well fitted by Langmuir model, and it indicates the monolayer adsorption on thehomogenous surface of the adsorbent. Thermodynamics results revealed that the Gibbs freeenergy ΔG of the BE 1:1 and BE 2:1 at 298 K, ΔG was positive indicates the process was notspontaneous. But after increasing temperature the reaction was spontaneous. Langmuir
separation factor (RL) value indicates the favorable adsorption conditions for phosphate.
Characterization of adsorbent was identified by FTIR, and SEM image. From FTIR analysis
the formation of the band at 1021 cm-1 was observed, which clearly indicated the presence ofphosphate after adsorption on BE 1:1. From kinetic study it has been found that the experiment
data were better fitted the pseudo second order model which explain that adsorption procedure
was chemisorption process. Presence of different ions (anions and organic acids) and pH of thesolution also influence the phosphate adsorption mechanism. But calcined BE 1:1 is noteffective for the organo-phosphorus herbicide glyphosate removal which is beneficiary for thisresearch because it will not compete with phosphate for active sides and don’t makecontamination in application of phosphate adsorbed material as fertilizer.
In this study phosphate desorption in Milli-Q water and NAC extraction method was examined.
Then phosphate dropped biochar was applied on pot experiment for Japanese mustard spinachcultivation. From the experiment it was found that phosphate desorption in Milli-Q water wasvery low. Because the bonding between calcium and phosphate is very strong. So, the reuse of
the adsorbent is not a good option. But the phosphate loaded eggshell modified bamboo char
was effective as slow-release fertilizer for the Japanese mustard spinach cultivation. So, thephosphate loaded eggshell modified bamboo char has potentiality to use in plant cultivation asa phosphorus fertilizer.

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