Generated in garbage dumps, materials recovery facilities or waste transfer stations, junkyards, molten metal baths, etc., leachates are highly polluting liquids which have filtered through solid waste due to percolation together with diverse chemical reactions of organic matter in a state of decomposition and other compounds. These liquids contain both suspended matter and dissolved matter, and if not properly collected and treated, they can pollute groundwater, jeopardizing both the environment and public health.

Polluting characteristics of leachates

• High COD and BOD5, and decompensation in COD/BOD5 ratio (revealing the existence of an important non biodegradable fraction).
• High nitrogen concentration, basically in the form of ammonium (NH4+).
• High salinity and conductivity (90%) produced by the presence of Cl-.
• High concentrations of halogenated organic compounds (AOX).
• Presence of inhibitors: principally traces of a wide variety of heavy metals.
• Large amounts of detergents, dissolved salts, and fouling agents (iron, calcium, and magnesium).
• Very low pH and phosphorus deficiency.

Leachate treatment plant in recycling park in Aranda.	All-embracing view of the plant in Aranda.

Conventional treatment

Biological, physical and chemical treatment complemented with micro/ultra filtration, ammonia stripping, chemical oxidations (H2O2, O3, UV, etc.), and activated carbon adsorption.

PHYSICAL AND CHEMICAL treatment (coagulation - flocculation) acts on the suspended fraction but not on the soluble fraction: this treatment removes suspended solids and solids in the colloidal state, heavy metals and other toxic pollutants by means of precipitation (high performance). COMPLEMENTED WITH AMMONIA STRIPPING, IT ALLOWS AMMONIUM REMOVAL BY MEANS OF DESORPTION.

Homogenizer grid.

Dosing equipment.

BIOLOGICAL treatment removes all soluble organic matter using hardly any reagent. MEMBRANE PROCESSES are very efficient systems: they remove water components by means of filtering water through micro/ultra/nano filtration membranes. MEMBRANE BIOREACTORS (MBR) achieve a total solid/liquid separation inside a bioreactor. SEQUENCING BATCH REACTOR (SBR) is an activated sludge system whose working principle is based on filling and emptying cycles which take place sequentially within the same tank. All our membrane processes have AUTOMATED SELF-CLEANING SYSTEMS which periodically clean the membranes, thus guaranteeing their OPTIMAL OPERATION.

Biological reactor grid.

External ultrafiltration membranes equipped with protection frame and system of signals to the electrical panel for automation.

Blowers for biological reactor.

Circulator pumps.

Also within the biological process, AMMONIACAL NITROGEN CAN BE REMOVED BY MEANS OF NITRIFYING-DENITRIFYING BACTERIA INSIDE PRESSURIZED REACTORS (NITRIFICATION-DENITRIFICATION): these bacteria turn ammonium into nitrogen by reducing the volume of organic matter and removing high fractions of BOD5 and of total nitrogen. Good biomass sedimentation and excess sludge stabilization.

As a complementary treatment, ACTIVATED CARBON ADSORPTION combines different granulometries in order to guarantee effluent quality, being able to remove up to 80% of non biodegradable COD (refractory COD). This system requires activated carbon regeneration once it is spent, and removing biological sludge from the vent so that it does not clog the filter. Not able to trap dissolved salts.

Treatment by means of one single membrane process

This system consists of ultrafiltration (already described), reverse osmosis, and evaporation/crystallization.

REVERSE OSMOSIS: It does not allow salts, antibiotics, nor essential oils through membranes. Capable of removing more than 90% of COD (even non biodegradable fraction), it retains very high percentages of dissolved salts (even Cl-) and produces a rejection with lower organic matter content. The result is an effluent which complies with regulations governing both effluent discharge into public sewer and effluent discharge into watercourse. Low energy consumption.

EVAPORATION / CRYSTALLIZATION: By means of heat application, leachates are evaporated, thus recovering water and concentrated salts. Afterwards, concentrated salts are crystallized. Biogas obtained in the plant is used as energy, either directly or using residual heat resulting from the movement of combustion engines and turbines due to mechanical power generated by biogas. This last system can generate electric power too. By means of methane gas transformation into energy, we control greenhouse gas emissions into the atmosphere, thus helping our planet while saving costs.

ALL OUR TREATMENTS ARE EASY TO CONTROL AND HAVE AUTOMATION CAPABILITY: IN PROSIMED, WE OFFER FULLY AUTOMATED PLANTS EQUIPPED WITH AMMONIUM METERS, CONDUCTIVITY METERS, OXYGEN METERS, PH METERS, ETC., CONTROL AUTOMATA, CONTROL VIA SYNOPTIC CHART WITH INTUITIVE TOUCH-SCREEN, AND POSSIBILITY OF TELEMANAGEMENT.

Recirculation pumps and measuring instruments.

Supports, blowers, pumps, and electrowelded polyethylene pipes.