Biological denitrification pilot in the Mar Menor (Murcia, Spain)

7 April 2022

BIOBOX® Nitrates has demonstrated its high efficiencyAll along a demanding pilot project in the D-7. It has achieved a nitrate removal in the Mar Menor of over 97% and an operating cost per m3 treated of less than €0.10.

Project description: Biological denitrification pilot plant in Mar Menor

The Mar Menor lagoon, located in Murcia (Spain) is the largest permanent body of salt water in Europe. It is a unique natural enclave of great ecological and scenic value. Until 2015 it was characterised as a place with a high biodiversity of fauna and flora and good levels of water quality. However, it is currently facing problems of nutrient pollution, mainly nitrates, which have generated a process of serious eutrophication of the lagoon.

Workers removing biomass / Source: Dossier June 2022 Mar Menor Channel

This has led the management of the Mar Menor to actively search for solutions and to look for more efficient ways to definitively eliminate the excess of nitrates that have been threatening the lagoon’s biodiversity for decades.  

As part of the specific action plan, it was decided to face this problem by using a biofiltration process based on biological heterotrophic nitrification. At that time, BIOBOX® proposed to carry out a pilot project to demonstrate the effectiveness of the BIOBOX® Nitrates (Puremust-sn®) technology.

As a result, a pilot plant was installed in April 2022 in the D-7 drainage channel of the Los Alcazares Wastewater Treatment Plant (WWTP).

Like all the plants offered by BIOBOX®, this pilot plant integrates advanced technology in both automation and sensor technology. This allows the plant to be operated autonomously and can be controlled remotely without the need for operating personnel.

Operating data and key measurement parameters are constantly monitored and recorded both locally and in the cloud. Having this data makes it possible to know how the plant is operating at all times with real-time or historical visualisation.

This four-month pilot project achieved outstanding results:

  • Nitrate removal performance over 97%.
  • Elimination remains constant and stable
  • The outflow COD remains well below the discharge to public watercourse and lower than the input COD
  • Cost of treatment below 0,1 €/m3
Pilot test results / Nitrate removal above 97%. Source: BIOBOX®

In conclusion: BIOBOX® has been chosen by the Government of Murcia as a technically and economically viable solution to eliminate nitrates from the wadis that flow into the Mar Menor. Throughout a demanding pilot project in the D-7 drainage channel, BIOBOX® Nitrates (Puremust-sn®) has demonstrated its high efficiency, achieving a nitrate elimination of over 97% and an operating cost per m3 treated of less than 0.10 €.

Technologies used:

Characteristics of the pilot plant:

  • Treated flow rate:0.24 m3/h
  • Nitrate input : 90-120 mg/l
  • Nitrate output: 5-15 mg/l
  • Biofiltering material: Filtralite® HC 2.5-5

Treatment process:

  • 1- Pre-filtration
  • 2- Biological denitrification by biofiltration

Biological denitrification pilot plant in the Mar Menor:

  • 4 Months (April 2022 – July 2022)

Explanatory video of the pilot test carried out:

On the occasion of the EU Green Week 2022, BIOBOX® created a webinar on the functioning of its BIOBOX® Nitrates technology and the successful results obtained in the demonstration pilot in the D-7 watercourse, in Los Alcazares, Mar Menor (Murcia).

Language: Spanish


General Directorate of the Mar Menor
Mar Menor Canal
Confederación Hidrográfica del Segura
European Regional Development Fund
Regional Entity of Sanitation and Purification