ADSORPTION EXTRACTION OF PHOSPHORUS FROM LIQUID WASTE WITH UTILIZATION OF SEDIMENTS IN FERTILIZER

Abstract

The study is dedicated to solving the problem of removing phosphorus from wastewater, which is extremely relevant in modern conditions of increasing anthropogenic load on water resources. Excessive input of phosphates into natural reservoirs causes intensive eutrophication, deterioration of water quality, reduction of biodiversity and increase in costs for water treatment. At the same time, phosphorus belongs to non-renewable minerals, the reserves of which are gradually depleted, which determines the economic feasibility of its return to the production cycle. Therefore, the combination of the wastewater treatment process with the subsequent use of extracted phosphates in the production of fertilizers corresponds to the principles of sustainable development and circular economy. The paper presents the results of an experimental study of the efficiency of phosphate removal from model solutions in dynamic and periodic conditions using adsorbents of various nature. In dynamic tests, the highest efficiency was demonstrated by natural zeolite, which provided a degree of purification of 94.5%, which significantly exceeds the indicators of activated carbon, glauconite and crushed walnut shell (67.75–76.5%). In batch conditions, the fastest phosphate removal (98% in 2 hours) was observed for activated carbon, but the zeolite showed a better balance between cleaning efficiency and the possibility of further environmentally safe disposal. Special attention is paid to the prospects of reuse of saturated adsorbents.It is shown that zeolite sediments can serve as an available raw material for the production of long-acting mineral and organo-mineral fertilizers that improve soil structure, increase moisture retention, and reduce the loss of nutrients. On the basis of the obtained data, an improved technological scheme of urban wastewater treatment with the introduction of the post-treatment stage in contact settling tanks with zeolite dosage (1 g/dm³, 60 min of contact) is proposed. The proposed solution provides not only a significant reduction in the concentration of phosphates, but also creates conditions for the integration of cleaning processes and resource recovery, which is an important advantage for modern treatment facilities.