Mobility and distribution of whey solutions in soil columns

Nara Cristina De Lima Silva,Hugo Alberto Ruiz,Leandro Da Silva Almeida

doi:10.14393/bj-v35n5a2019-42253

Abstract

In Brazil’s food industry, dairy production is one of the most important sectors, whose most relevant byproduct is whey. Due to the difficulties of reuse and environmental impacts caused when discarded as effluent in water bodies, an alternative for its final destination would be the application of this residue in the soil. The purpose of this study was to determine chemical changes and mobility and distribution of solutes in the soil after applications of whey rates, as well as to analyze the leachate collected after each application. The test was carried out in a laboratory, in PVC columns filled with soil. The treatments consisted of 2 x 2 samples of a typical dystrophic Red-Yellow Oxisol (Oxisol) and a typical dystrophic fluvic Inceptisol (Inceptisol), sampled in the layers 0- 20 and 20-40 cm. Each experimental unit consisted of 11 PVC rings (diameter of 6.6 cm, height of 7 cm). The columns were arranged in a randomized complete block design with five replications. Four whey rates were applied, corresponding to a soil pore volume of 0.2, at intervals of six days. The leachate was collected 24 and 120 hours after each application to measure pH, electrical conductivity (EC), chemical oxygen demand (COD), contents of total N, N-NH4+, N-NO3-, Na, K, Ca, and Mg. Six days after the last whey application, the columns were opened and the soil of each ring was analyzed for pH, EC, total N, N-NH4+, N-NO3-, Na, K, Ca, and Mg. The high electrolyte concentrations of whey resulted in a general increase in soil EC. The increase of N-NH4+ and N-NO3- in the soil was high due to mineralization. High concentrations of K, Na and Ca caused displacement of Mg from the exchange complex. It was concluded that from an environmental standpoint, whey soil application is a viable alternative, given that problems of salinization and leaching of undesirable elements are avoided by an adequate management.

Highlights

Whey consists of a milk co-product that is extracted from milk coagulation in the cheesemaking process (BRAZIL, 2013)
As for leachate collection, there was a marked drop in volume during leaching
The application of whey in the soil as the final destination for this residue is an environmentally viable alternative, provided that a correct management is made in order to avoid problems of surface sealing, salinization and leaching of undesirable elements

Summary

Introduction

Whey consists of a milk co-product that is extracted from milk coagulation in the cheesemaking process (BRAZIL, 2013). This residue stands out due to the large volume generated (about 9 L kg-1 of cheese manufactured) and its quality characteristics, which allow several possibilities of use. Whey represents approximately 80 to 90% of the milk volume and contains 55% of its nutrients, the water content varies from 91 to 95% (SILVA, 2006). The beneficiation processes allow the wide use of this residue in the manufacture of other products in the food industry and even in the pharmaceutical industry (MAHMOUD, 1994; BOUNOUS et al, 1999). The recovery of whey substances for such purposes depends on the availability of appropriate techniques and the use of economically viable processes

Objectives

Methods

Results

Conclusion