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Emergency environmental issue solved with Klarwin reverse osmosis system – Cluj, Romania

Application:

The Pata Rât Municipal dump, near Cluj, occupies an area of 8.96 ha with 400.000 m³ waste/year stored. The dump surface is unbalanced, with waste deposit heights ranging from 3 -15 m, dump slopes exceeding 45°, forming embankments near the Zăpodie stream, which is 2-10 m away.

Challenge:

The poor physical stability of the landfill and strong precipitation in summer 2017 resulted in sliding of parts of waste over the Zăpodie stream and the communal road.  The Cluj authorities have declared the situation an environmental emergency due to contamination of surface and ground waters.

Measurements of pH in surface water and leachate signify alkaline water

Six samples from Zăpodie stream and leachate were taken each month, starting January until May 2012 [1]. The pH values show a slightly alkaline water, but within the limits imposed by 161/2006 Governmental Order regarding the surface waters. Below is represented the variation in pH of a sample from Zăpodie stream, approximately 200 m after the landfill, in 5 months.

The leachate has a pH between 8.01 to 8.79 pH units, with a strongly alkaline reaction, which is usual for landfills in the first two years of operation.

Extreme values of dissolved solids in surface water require fast actions

Romanian legislation does not provide restrictions for conductivity (EC) and total dissolved solids (TDS) in natural water, but sample analysis results show increased values than usual. The stream water EC is up to 20 times bigger than the usual limit of 1000 µS/cm [2], found in literature, which indicates severely polluted water. The TDS values were up to 27 times larger than usual TDS value in fresh water [3], signifying change in ionic composition of water. Below is represented the variation in TDS and EC from Zăpodie stream, approximately 200 m after the landfill, in 5 months.

High concentration of Ca2+ and Mg2+ ions in the surface water has negative impact on the aquatic fauna. Ca2+, Mg2+ and Na2+, forms bicarbonates, nitrates, sulphates or chlorides in surface water. Presence of Mg2+ influences growth of some bacteria. [1]

The leachate analysis revealed concentrations of heavy metals like Zn, Cu, Cd, which have a toxic effect on the ecosystems and underwater organisms. As the pH is expected to decrease in the future, the heavy metals’ (Zn, Cu, Cd etc.) solubility will increase. [1]

Solution:

Cluj County’s decision was to treat the leachate on-site, using Klarwin reverse osmosis (RO) technology (1).

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484_Inaugurare CMID Cluj - 22.05.2020 - NIC_0573

The recommended technical solution included drainage layer, drainage collector network, buffer tank (2) and leachate treatment plant (3).

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The solution is based on the patented Disc Tube module (4), which consists of a chamber of hydraulic discs interleaved with ultrasonically welded, long-lasting membrane cushions.

In the reverse osmosis process, pressure is applied to leachate to force the pure water molecules through a semi-permeable membrane.

Most of the toxic, organic and metal components in water, along with bacteria, are unable to pass through the membrane, remaining in the concentrate.

Laboratory analysis of 35 parameters were investigated each month since the installation of the unit in July 2018.

Some of the parameters were exceeded tens, hundreds of times, which is a real danger to environment.

For example, ammonium (NH4-N) is 629 times larger than the permitted limit according to NTPA001 for concentration values in wastewater discharge in aquatic environment.

There is significant exceedance in the mineral loading measured by the following indicators: Ca2+, Mg2+, Na2+, SO42-, and some metals measured by the Zn, Cu, Ni indicators.

Below is represented the relative difference of all exceeded parameters with respect to the allowable limit in NTPA001, found in leachate and permeate in September 2018.

The result is a pure permeate stream (5) under the limits stated in the NTPA 001.

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Klarwin makes sure all parameters in the permeate are below maximum allowable limit. The reverse osmosis unit is continuously working since July 2018, proving “Fluid Perfection” is possible.

Benefits:

  • Small footprint
  • “Plug & Play” installation with a short start-up period
  • Easy Maintenance – modules can be opened and tested, a single cushion can be replaced
  • Less susceptible to scaling and fouling due to high flow velocities
  • No chemical pre-treatment needed
  • Low operating costs.

References:

[1] Lengyel A., Reti K.-O., Roşu C., Manciula D. (2013), The Impact Of Cluj-Napoca Municipal Landfill On Zăpodie Stream Water Quality, Aerul și apa componente ale mediului, Ed. Presa Universitarp Clujeană, Cluj-Napoca, pg. 337-344
[2] Vigh M., (2008), Calitatea apei râurilor din bazinul hidrografic al Târnavei, Ed. Casa Cărţii de Ştiinţă, Cluj-Napoca.
[3] Réti K.O., Vigh M., Csifo I., Kelemen Sz., (2011), Analiza indicatorilor fizicochimici pe Valea pârâului Trânghieşti – platoul carstic Padiş, Ecoterra, 29, pg. 74-78.