General Information
Wastewater generated from olive mills, consist a significant pollutant factor in olive producing areas, and also a major matter to be for the agricultural industry.
The main reasons for this statement can be described as follows:
  • High waste production on a relatively short period of time, in which under ideal conditions, have to be treated or to be disposed with safety in the environment prior to the commencement of the next production period. Produced wastewater volumes depend on multiple factors, such as the olive variety, maturation stage, storage time prior to olive production, the olive oil’s separation time from olive residues, the amount of available water in an olive mill and its buying cost. Generally for every 100 kg of olives 100-120 kg of wastewater is produced, with an average daily production value per olive mill, estimated around 15-20 tons.
  • The wastewater’s physico-chemical characteristics, which can affect severely the aquifer that are disposed (e.g. eutrophication, occurrence of toxic effects on aquatic fauna, phytotoxicity, and aesthetic degradation).
  • The notable high organic pollutant load of such type of wastewater, which is comprised both of readily cleavable compounds (e.g. sugars, organic acids, amino acids, proteins), as well as from compounds non easily cleavable (e.g. multi-molecular fatty substances, polyphenols). Polyphenols in this wastewater type are contained in high concentrations and are responsible for the occurrence of bio toxic effects on aquifers.

Olive mill wastewater contains as well, multiple inorganic substances (nitrogen and phosphorous compounds, sodium, potassium, iron, etc). Although these inorganic substances are not toxic, their high concentration and recurrent disposal may cause environmental issues.
The main characteristics olive mill wastewater are presented on table 1.
Table 1. Olive mill wastewater characteristics
Characteristic Value Range
Ph 3,4 - 9
Conductivity (mS/cm) 23 - 146
Turbidity (NTU) 200 - 720
TOC (mg/lit) 18.000 – 35.000
Polyphenols (g /lit) 0,98 – 2,34
COD (mg/lit) 36.000 – 130.000
BOD (mg/lit) 12.000 – 43.000

The GACS Solution (Geochemical Active Clay Sediment)
The Geochemical Method GACS consists an innovative solution on an international level on the subject of treatment and disposal of olive mill wastewater. The key characteristic of the Geochemical Method GACS is the usage of geopolymer materials, which have the ability to adapt on the characteristics and particularity of any type of waste. Under this manner, process optimization and performance maximization are achieved.
Benefits of the GACS Method, on treatment of olive processing wastewater against the conventional existing methods can be summarized in the following:
Financial Benefits:
  • Competitive investment cost
  • Significantly reduced operational cost
  • Reduced maintenance cost
  • Reduced sludge production
  • Reduced operational time

Environmental Benefits:
  • Heavy metals removal even on high concentrations.
  • Effluent complying with registration depending on the usage
  • Production of water that can be used for irrigation
  • Production of inert sludge which is suitable as soil fertilizer
  • Use of natural materials
  • Elimination of odors