Chemical amelioration of nepheline sands using sewage sludge from a regional wastewater treatment plant

Abstract

The studies on the use of municipal wastewater sludge as an unconventional chemical ameliorant with a fertilizing effect were carried out on ore dressing waste ("tailings") of the apatite-nepheline plant ANOF-2 KF JSC "Apatit" with a predominance of nepheline sands in their composition. The tailings dump is included in the list of objects of accumulated environmental damage in the region, but due to its rich mineral composition, it is recognized as a technogenic deposit subject to conservation for the prospect of obtaining apatite, nepheline, sphene, aegirine and titanomagnetite concentrates. In the work, the method of phytotesting of soil irrigated with unfiltered rainwater with fragmentary application of sewage sludge of a regional wastewater treatment plant enterprise has been applied. The experiments have been carried out on a single-species seed recommended for reclamation of disturbed territories in the northern regions. During the formation of a sown phytocenosis from meadow timothy ( Phleum pratense L.) on nepheline sands, the stimulating effect of sewage sludge on the nutrient regime of the soil is confirmed. After phytoextraction (at the end of the experiment), it retains a high residual pool of basic nutrients (N, P, K), which indicates a prolonged action of sewage sludge. To confirm the effect obtained in laboratory conditions, a field experiment has been laid at the ANOF-2 reserve tailing dump in 2019, observations are continuing.