In September 2021 a new and exciting project was delivered for a mining company located in the south of Ecuador. The challenge involved the design and construction of a biological wastewater treatment plant in just 6 weeks.
The mining camp had an existing WWTP that treats wastewater from bathrooms and kitchens. However, the water from the secondary settling of this WWTP contained high levels of nutrients.
The discharge of nutrients, especially nitrogen and phosphorus, causes eutrophication in surface waters, with seasonal algal blooms being a common result. It causes serious problems for ecosystems and people due to low dissolved oxygen, fish kills, turbid water and depletion of flora and fauna.
To avoid this problem, BIOBOX® proposed a compact solution in a container after the existing pre-treatment. This offers a technically and economically feasible solution with a very small footprint (1 x 40′ container).
The plant is designed to remove COD, nitrogenous pollutants (ammonium), nitrates and phosphorus from an influent of 31 GPM (7 m³/h)
Although the plant was initially designed to treat concentrations of 250 mg/L of nitrate (NO3–) (N-NO₃: 56 mg/L) and 60 mg/L of ammonium (NH4+) (N-NH₄⁺: 47 mg/L), meeting the discharge limit of 10 mg/L, it ultimately managed to treat 400 mg/L of nitrate (NO3–) (N-NO₃: 90 mg/L) and 60 mg/L of ammonium (NH4+) (N-NH₄⁺: 47 mg/L) , while maintaining the same discharge compliance. Additionally, this process removes over 6 mg/L of phosphorus to meet the IFC standard
The plant’s water treatment line is organized in three stages: an initial pre-filtration, a biological denitrification and a biological nitrification.
The initial pre-filtration is performed using a specific material designed to smooth out peaks of suspended solids (SS). Following this, an intensive anoxic denitrification process is carried out in three pressurized filters, designed to reduce the concentration of nitrates in the water. This process is automated with probes that monitor various parameters such as NO3-, ORP, pH, and flow rate, and it is controlled by a PLC.
This type of denitrification, which consumes organic matter in combination with the biological oxygen demand (BOD) remaining in the wastewater, is similar to the treatment used in plants to reduce nitrates in well water with high concentrations of this compound.
Finally, the water undergoes a biological nitrification process in a biofilter, using a specially designed bed for this purpose, with the addition of alkalinity to remove ammoniacal nitrogen.
Like all installations of this type manufactured by BIOBOX®, the entire treatment line is fully sensor-equipped. It works automatically and sends all analytical and performance data to a central server.
The installation met some milestones in terms of planning and execution, from project definition to delivery to port in less than 5 weeks.
Thanks to its fully prefabricated design, installation and commissioning were streamlined, allowing for a faster start-up of the on-site biological systems. Remote monitoring was implemented, and complete operational and maintenance knowledge was transferred to the end-user during the commissioning phase.
In conclusion, this plant proved to be the best solution for a total nitrogen elimination of 90%, complying with river discharge regulations and allowing the mining company to successfully continue with its policy of minimizing environmental impact.
Technologies used:
- 1. BIOBOX Nitrate
- 2. BIOBOX Ammonium
- 3. BIOBOX Organic Matter
- 4. Phosphorus elimination treatment.
- 5. BIOBOX Combined contaminants
Plant characteristics:
- Influent: Wastewater
- Technology: BIOBOX Nitrate; BIOBOX Ammonium; BIOBOX Phosphorus
- Flow rate: 31 GPM / 7 m³/h
- Influent N-NO₃: 90 / (NO₃ : 400 mg/L)
- Influent N-NH₄⁺: 47 / (NH₄⁺: 60 mg/L)
- Effluent Total N: <10 mg/L
- Phosphorus input: 8 mg/L
- Phosphorus output: <2 mg/L
Plant steps:
The water treatment line consists of three steps:
Initial Prefiltration
Biological Denitrification
Biological Nitrification