Carrion de los Céspedes

S1-S2-S3-S4

• Dimension: 4 units x 6.50 x 3.70 m (24.05 m²)= 96.2 m²
• Population served: 4 X 50 pe = 200 pe
• Design of the unit: The iMETland flow-sheet includes: pretreatment (coarse and fine screen and grit&grease chamber), Imhoff tank (primary settling and digestion- HRT= 90 min in the settling area at maximum flow; cumulative sewage sludge 140 l/pe·year); pumping station; iMETland filtering media (4 units); disinfection camera – electro-disinfection (HRT = 30 min).
• Filtering media: the iMETland unit has been constructed in a 1.2-m-depth concrete vessel. At the bottom of the vessel, drainage and ventilation pipes are placed (PVC 90 mm-perforated pipes). For improving the aeration of the electroactive media, four vertical PVC pipes have been connected to the drainage system (90 mm diameter) through "T-pieces". The drainage pipes are covered with a 30-cm- thickness gravel (12 mm) layer. Over the fine gravel layer, the electroconductive material is placed. The four iMETland units present different internal configurations in relation to the conductive material:
  1. S1: above the bottom gravel layer, 40 cm of conductive material- coke (10-30 mm) is placed and, then, another 40 cm of fine conductive material- coke (3-10 mm).
  2. S2: only one layer of 50 cm of fine conductive material-coke (3-10 mm) was placed above the bottom gravel layer. In a second stage it was increased to 80 cm of the same material.
  3. S3: above the bottom gravel layer, 50 cm of conductive material- coke (10-30 mm) is placed and, then, another 25 cm of fine conductive material- coke (3-10 mm).
  4. S4: above the bottom gravel layer, 40 cm of conductive material- coke (10-30 mm) is placed and, then, another 40 cm of BIOCHAR, whith intermediate aeration pipes.

  The conductive material is then covered by a 5-10 cm-thickness layer of fine gravel (6-12 mm) for the plantation of the METland and for facilitating the homogeneous distribution of the inlet water along the iMETland’s surface

• Expected results: The iMETland units have been designed for meeting the discharge limits imposed by the Directive 91/271/EEC, concerning the treatment of urban wastewaters. Therefore, the expected results are (for the main monitoring and control parameters): COD < 125 mg/l, BOD₅ < 25 mg/l and SS < 35 mg/l.
• Monitoring results: The following table summarizes the results obtained in the iMETland units (96 m²)

Carrion de los Céspedes - 50 PE

• Dimension: Package version –20 m²
• Population served: The unit is designed for a population up to 50 PE
• Design of the unit: The flow sheet includes: screening, primary settling tank (settling and digestion of sewage sludge) and the iMETland-20m² unit
• Filtering media: the package iMETland unit has been built inside a 5 m diameter-FRP (fiberglass reinforced polyester) deposit. The layers of filling material (from the bottom to the top) are:
  • 20 cm of thick gravel (25-40 mm)
  • 60 cm of conductive material (1-3 cm)
  • 15 cm of thick sand (1-3 mm)

  The package version can work in a dual mode: upflow (the filtering media is flooded) and downflow (aerated conditions are predominant).

• Expected results: The iMETland units have been designed for meeting the discharge limits imposed by the Directive 91/271/EEC, concerning the treatment of urban wastewaters. Therefore, the expected results are (for the main monitoring and control parameters): COD < 125 mg/l, BOD₅ < 25 mg/l and SS < 35 mg/l.
• Monitoring results: The following table summarizes the results obtained in the iMETland 50 PE (20 m²)

Orby - Denmark

• Dimension: The unit consists of 2 bassins of each 40 m2, 80 m2 in total
• Population served: The system serves 200 pe
• Design of the unit: The flow sheet includes: screening, primary settling tank (settling and digestion of sewage sludge) and the iMETland-20m² unit
• Filtering media: The package iMETland unit has been built inside a 5 m diameter-FRP (fiberglass reinforced polyester) deposit. The layers of filling material (from the bottom to the top) are:
  • 20 cm of thick gravel (25-40 mm)
  • 60 cm of conductive material (1-3 cm)
  • 15 cm of thick sand (1-3 mm)

  The package version can work in a dual mode: upflow (the filtering media is flooded) and downflow (aerated conditions are predominant).

• Expected results: The iMETland units have been designed for meeting the discharge limits imposed by the Directive 91/271/EEC, concerning the treatment of urban wastewaters. Therefore, the expected results are (for the main monitoring and control parameters): COD < 125 mg/l, BOD₅ < 25 mg/l and SS < 35 mg/l.
• Monitoring results: The following table summarizes the results obtained in the iMETland 50 PE (20 m²)

Mar de Plata

• Dimension: 80 m2
• Population served: 200 PE
• Design of the unit: Four iMETland units of 20 m2 each were constructed. Units are fed with primary wastewater coming from a 20 m3 septic tank and operate downflow. Reeds, papyrus and iris (species present in regional natural wetlands) were planted on the system.
• Filtering media: Units have a top layer of coarse sand to stimulate nitrification, followed by a layer of 10-30 mm conductive particles that stimulate direct interspecies electron transfer.
• Expected results: According to the project schedule, the mean organic load will be increased by 50% every 2 months, to reach a final value of 200 g_COD m^-2 d^-1 during next year. A similar reduction of COD than that observed during start-up phase is expected. Also, higher removal rates of nitrogen are projected, as plants species and microflora will continue developing during summer.
• Monitoring results: During start-up phase organic load was progressively increased up to 100 g_COD m² d^-1. COD was reduced by almost 90% with a mean outlet concentration of 47 mg l^-1. The treatment of 100 g_COD m^-2 d^-1 represents a 5 fold increase compared to typical design parameters of vertical flow wetlands. Total nitrogen concentration on the inlet of the iMETland unit was 94 mg l^-1, comprised by 89 mg l^-1 of ammonia, 3 mg l^-1 of organic nitrogen and 2 mg l^-1 of nitrate. These values are higher than the limits set by the local control authorities for the discharge to surface water bodies. 80% reduction of ammonia and 30% reduction of total nitrogen were already achieved enabling wastewater use for irrigation aims even during start up.