Recovery and utilization of phosphorus from fruit and vegetable wastewater

Yu Qin,Deyin Hou,Xiaoxu Zheng,Shengjun Xu,Xiaohan Zhang,Kai Li,Ping Lyu,Wei Zhang,Cong Wang,Shuanglong Ma,Huili Li

doi:10.1038/s41598-021-04430-1

Abstract

Excessive discharge of phosphorus into the water bodies is the key factor to cause eutrophication. The fruit and vegetable wastewater contains large amounts of phosphorus, and it may be directly discharged into water bodies, which has a great burden on the municipal sewage pipe network. Therefore, coagulation was used to remove phosphorus, recovered the phosphorus from the wastewater into the precipitate, and then the precipitate was pyrolyzed as an efficient adsorbent for phosphate removal. By comparing the adsorption effects of adsorbents (XT-300, XT-400, and XT-500) with pyrolysis temperatures of 300 °C, 400 °C, and 500 °C on phosphate in actual phosphorus-containing wastewater and simulated phosphorus-containing wastewater at different adsorbent dosage (4 g/L, 7 g/L, and 10 g/L), it was found that XT-300 had the best performance of adsorption, and the adsorption of phosphate was endothermic and obeyed the Langmuir isotherms and Elovich kinetics. The influence of pH, coexisting anions, and the structure of XT-300 revealed that the removal of phosphate was associated with electrostatic attraction, pore filling, but could not be determined whether it was related to surface precipitation. This study provides a way and method for the recovery and utilization of phosphorus in fruit and vegetable wastewater and proves that the synthetic adsorbent was an efficient phosphorus adsorbent. In the long term, we can try to use the adsorbent after phosphorus adsorption to promote plant growth in agricultural systems.

Highlights

Carbon-based material is a kind of pyrolysis black carbon
Part of carbon, nitrogen, and phosphorus in fruit and vegetable wastewater were successfully precipitated by the combined coagulation of polyferrous sulfate (PFS) and PAM, in which the removal of phosphorus reached more than 50%, and the recovery of phosphorus was effectively realized
It was found that XT-300, XT-400, and XT-500 had the performance of adsorption on phosphate removal, and XT-300 had the best performance of adsorption

Summary

Introduction

Carbon-based material is a kind of pyrolysis black carbon. Its production has many environmental benefits, such as carbon sequestration, global warming mitigation, soil quality improvement, and contaminant removal[16,17,18]. In this study, taking the fruit and vegetable wastewater as the matrix, most of its granular substances, especially phosphorus, are flocculated and precipitated by coagulation, and the precipitates are employed as raw materials to fabricate phosphorus adsorbent. The main purposes of this study are as follows: (1) Using the method of coagulation to coagulate and remove the high carbon, high nitrogen, and high phosphorus in fruit and vegetable wastewater, and the recovered precipitates to prepare a new phosphorus adsorbent; (2) To analyze the adsorption process by batch experiment and model analysis; (3) To explain the adsorption mechanism by various characterization. This study is expected to verify that the synthesized carbon-based material was an efficient phosphorus adsorbent, which could be used for phosphate adsorption in actual water bodies, to provide a method for the preliminary recovery and utilization of high carbon, high nitrogen, and high phosphorus in fruit and vegetable wastewater

Methods

Results

Conclusion