**6.1.3 Treatment wetlands (TW)**

208 Studies on Water Management Issues

*Design:* Two pilot VDD (Figure 3) were constructed in agricultural area to reduce watercourse pollution, draught threat, to mitigate agricultural contaminants, and to develop new wetland habitats in order to improve biodiversity. Ditches approx. 20 m long, 5 m top width, 1.40 m bottom width and 1.5 m deep were filled with selected substrata of 0.4 m in height and planted with macrophytes (*Phragmites australis*) (Griessler Bulc & Šajn-Slak, 2007; Griessler Bulc et al., 2011). In one of the VDD, the treated water flows into a meandering stream of an overall length of 70 m where the revitalization principle was followed to

*Monitoring:* From April 2008 until March 2009, physical and chemical parameters and pesticides in water were sampled and analyzed according to Standard Methods (APHA, 2005). The treatment performance was also monitored by localization of the principal denitrification processes within the VDD. The location and relative abundance of denitrifying microorganisms was determined by real time PCR (rtPCR) of the narG gene.

*Results and Discussion*: With the exception of SS, pollutant concentrations met the outflow permitted levels (OG RS 47/2005). The comparison of our results with the results of monitoring of the same system in previous years showed that the VDD's efficiency for nitrite and ammonia increased due the maturity of the system. The analyses showed also 91 % removal efficiency for metholaclor pesticide. A relatively even distribution of the narG gene showed the flexibility of the VDD system. The results indicate that the facultative anaerobic denitrifiers were present throughout the system, and when the conditions were suitable, denitrification was performed. The research showed that the regularly maintained VDD efficiently decreased pollutants and is an adequate and promising technology that can be further developed. Start-up period with non-consistent treatment performance could be significantly decreased with bioaugmentation with a proliferous and well adapted microbial

drainage ditch

**VDD**

**6.1 Design and performance of different ET types** 

further increase the water quality and biodiversity.

**6.1.1 Vegetated drainage ditches** 

community.

**VDD** riverbed

meander

**VDD Glinščica VDD Lešnica** Fig. 3. Design of the two VDD Glinščica and Lešnica (source: LIMNOS Ltd., CGS plus Ltd.) *Design:* From 1989 to 2011, over 73 TW were constructed in different regions of Slovenia. Most TW are horizontal or/and vertical systems (VF, HSF), operating in combination or integrated in zero foot print unite. Most of them consist of several interconnected beds. Most TW were installed to treat sewage, industrial wastewater, highway run-off, gray water for toilet flushing, drinking water, water from fish farms and landfill leachate. Pre-treatment mostly comprised septic tanks or sedimentation basins. Excavations were sealed with PVC or HDPE membranes, clay or the combination of both. The medium was mostly a mixture of different material (peat, soil, sand, gravel, expended clay), varying in grain size and proportion. The depths of the TW varied from 0.5 to 0.8 m, and the bottom slope from 0 to 3 %. Most systems were between 20 and 1500 m2 in area (Table 1). Theoretical hydraulic loading of media was in each case at least 10-3 m/s. The TW for sewage vary in size with 2- 2.5 m2 per people equivalent on average. Wide adaptability to different environmental conditions, tolerance to stress, high productivity is evident characteristic of *P. australis* that favoured the use of this species in TW. Different parts of reed were used for planting, most frequently clumps. In shallow beds of integrated systems, where the depth was 0.4 m, other species, such as *Juncus effusus, J. inflexus, Carex gracilis, Schoenoplectus lacustris*, and *Thyphoides arundinacea,* were successfully tested. Systems were planted generally in spring or autumn when the environmental conditions were optimal.

*Monitoring:* The efficiency of TW was monitored by sampling at the inlets and outlets in different periods between 1989 and 2011. TW for landfill leachate were monitored regularly on a long-term basis, from 1992 till 2003, while other systems were monitored monthly for one year or occasionally for one up to 5 years. The efficiency of TWs was evaluated by analyzing suspended and settlements solids, COD, BOD5, total phosphorus and ammonia nitrogen. Grab samples were taken mostly according to the measured retention time and analyzed by independent laboratories. Analyses were done according to Standard Methods (APHA, 2005). At sampling sites, flow, temperature, pH, dissolved oxygen and electric conductivity were measured. More extensive chemical and microbiological analyses were done occasionally.

Ecosystem Technologies and Ecoremediation for Water Protection, Treatment and Reuse 211

*Results and Discussion:* The obtained results confirmed the findings that leachate can be a good fertilizer for short rotation coppice produced elsewhere for energy crops. The macronutrient requirements of willow, in relation to nitrogen set to 100, were found to be for N:P:K in the relation of 100:14:72. The N:P:K ratio usually found in leachate ranges from 100:0:54, respectively (Duggan, 2005) to 100:1.5:103 (Dimitriou et al., 2006). The N:P:K ratio calculated from the average concentration of nitrogen, phosphorous and potassium in leachate analyzed during 18-month period was 100:0.5:246, respectively. The potassium concentration was found in excess and phosphorous concentration was low as it is common for leachate. The lack of phosphorous for plant growth is usually expressed in a long-term period (>10 years) and its deficiency could therefore not have been expressed during our

*Case 2; Design:* A phytoremediation method for the treatment of tannery substrate on the industrial waste dump in Slovenia was used in 2006 to research the potential of various plant species to reduce Cr pollution. Several herbaceous and woody species were planted in the tannery substrate in a greenhouse and on the four testing polygons on the waste dump. *Monitoring:* Prior to planting, hardly degradable and toxic substances in the substrate and leachate were analyzed. Moreover, the substrate was examined for its inhibition and chronic toxicity to higher plants according to the ISO standard (ISO/DIS 22030). Several growth parameters were measured in the glasshouse and on the polygons. The growth parameters were measured on a monthly basis in the growing season. Prompt fluorescence, i.e. potential photochemical efficiency (parameter Fv/Fm), was measured on the plants in the glasshouse

*Results and Discussion:* The preliminary substrate analyses had shown that the most crucial pollutant in the tannery landfill site was Cr (III). The biological accessibility of Cr in roots and shoots of herbaceous and woody plant species showed that beet and sunflower were the most suitable species for phytoremediation, although Cr bioavailability was low. The results revealed that the growth of plants was inhibited and, their health worsened. The results also showed that phytoremediation could be a very delicate method that needs a

*Design:* The majority of watercourse revitalizations in Slovenia were carried out in the north-east part of the country. Revitalizations of short stretches of rivers and streams were designed in order to increase self-cleaning capacities of the streams in an intensive agricultural landscape and also in order to protect the natural population of otter. According to the data, the most continuous and viable population of *Eurasian otter* in Slovenia lives in the north-east of the country. Threats for otter in this area are degraded habitats due to the agro-operational works, including ameliorations and canalization of watercourses which took place in last decades. The results of non-sustainable management were among others the opening of corridors by removing tree canopies as well as riparian vegetation on watercourse banks (the shelter for otters disappeared, the living conditions for pray species worsened and consequently the food supply was reduced), the permeability of corridors had lowered and the risk for population fragmentation was higher. In order to protect and restore the otter population, ETs were implemented in

careful insight into the processes of specific pollutants removal.

observation.

and on polygons.

**6.1.5 River revitalization** 

*Results and Discussion:* Most TW were satisfactory efficient in BOD5 and COD removal, and only partly efficient in N and P removal. The TW for industry were constructed for the treatment of food processing wastewater, characterized by high COD, BOD5, and ammonia nitrogen and for dye-rich textile wastewater. The results indicated that TW can be an appropriate technology for the treatment of wastewaters from those industries because the outflow parameters reached the prescribed legislation standards (Griessler Bulc & Ojsteršek, 2008; Zupančič Justin et al., 2009). Two pilot TW were constructed at the end of 2005 for the treatment of water from drinking water wells, polluted with pesticides (atrazine, metholaclor), and pathogens. The results showed the removal efficiency of *E.coli* from 130 to 500 bacteria/100 mL at the inflow to 0 to 3 bacteria/100 mL at the outflow from TW (Istenič et al., 2009). Regarding the pesticides removal, bentazon was reduced from 1.8 μg/L at the inflow to 0.06 μg/L at the outflow, metholaclor from 0.73 μg/L to <0.05 μg/L, and terbutylazine from 0.53 μg/L to <0.03 μg/L (LIMNOS Ltd., results not published). TW for highway run-off treatment showed 69 % removal efficiency for suspended solids, 97 % for settleable solids, 51 % for COD, 11 % for BOD5 and 80 % for Fe. Heavy metals (Cu, Zn, Cd, Ni and Pb) were below the legislation limits at the inflow with the reduction efficiency in the system of over 90 % while the concentrations of N and P showed a low level of nutrients for biological processes (Bulc and Sajn Slak, 2003). The TW for gray water was constructed in 2011. Preliminary data showed that gray water was mostly lost due to evapotranspiration. The TW for landfill leachate were constructed for the landfill sites that cover approximately 0.5 to 2 ha. With regard to the studied parameters, the performance of TW was not influenced by annual seasons, but primarily by precipitation. The reduction efficiency reached on average 50 % for NH4-N, BOD5 and COD (Griessler Bulc, 2006; Griessler Bulc & Zupančič Justin, 2007). The results proved that a TW can be considered a method appropriate for the leachate treatments of old waste dumps (Zupančič Justin et al., 2005).

### **6.1.4 Restorations of landfill sites**

*Case 1; Design:* The ET approach for the reclamation of a 1.5 ha landfill in south-eastern part of Slovenia consists of a landfill soil cover, which is densely planted with grasses and fast growing trees (poplars, willows) as a phytoremediation layer, a TW of 1,000 m2 with an average hydraulic load of 12 m3/d and an irrigation system. Landfill leachate is treated in the TW from where it is recycled on the landfill cover without outflow into the environment. Closed loop leachate circulation enables additional leachate treatment by assimilation of nutrients into the plant biomass and by mineralization processes of microbes in the soil layer. Fast growing trees allow the evapotranspiration of a considerable amount of leachate, while the excess percolates back into the landfill body and enables further biodegradation of deposited wastes. The results provided an environmentally and economically-viable solution, with large buffering capacity and simple in concept. The presented methods won international awards (2001 Lillehammer Award; 2008 Global Energy Award, Griessler Bulc & Zupančič Justin, 2007).

*Monitoring:* To evaluate plant response on leachate irrigation, a remote sensing of the canopy reflectance was performed by ground-based monitoring of vegetation indices of the phytoremediation system with a multispectral camera (Tetracam, USA). Images were taken in regular monthly intervals during one vegetation season, from April to October, after two years of leachate irrigation.

*Results and Discussion:* The obtained results confirmed the findings that leachate can be a good fertilizer for short rotation coppice produced elsewhere for energy crops. The macronutrient requirements of willow, in relation to nitrogen set to 100, were found to be for N:P:K in the relation of 100:14:72. The N:P:K ratio usually found in leachate ranges from 100:0:54, respectively (Duggan, 2005) to 100:1.5:103 (Dimitriou et al., 2006). The N:P:K ratio calculated from the average concentration of nitrogen, phosphorous and potassium in leachate analyzed during 18-month period was 100:0.5:246, respectively. The potassium concentration was found in excess and phosphorous concentration was low as it is common for leachate. The lack of phosphorous for plant growth is usually expressed in a long-term period (>10 years) and its deficiency could therefore not have been expressed during our observation.

*Case 2; Design:* A phytoremediation method for the treatment of tannery substrate on the industrial waste dump in Slovenia was used in 2006 to research the potential of various plant species to reduce Cr pollution. Several herbaceous and woody species were planted in the tannery substrate in a greenhouse and on the four testing polygons on the waste dump.

*Monitoring:* Prior to planting, hardly degradable and toxic substances in the substrate and leachate were analyzed. Moreover, the substrate was examined for its inhibition and chronic toxicity to higher plants according to the ISO standard (ISO/DIS 22030). Several growth parameters were measured in the glasshouse and on the polygons. The growth parameters were measured on a monthly basis in the growing season. Prompt fluorescence, i.e. potential photochemical efficiency (parameter Fv/Fm), was measured on the plants in the glasshouse and on polygons.

*Results and Discussion:* The preliminary substrate analyses had shown that the most crucial pollutant in the tannery landfill site was Cr (III). The biological accessibility of Cr in roots and shoots of herbaceous and woody plant species showed that beet and sunflower were the most suitable species for phytoremediation, although Cr bioavailability was low. The results revealed that the growth of plants was inhibited and, their health worsened. The results also showed that phytoremediation could be a very delicate method that needs a careful insight into the processes of specific pollutants removal.

### **6.1.5 River revitalization**

210 Studies on Water Management Issues

*Results and Discussion:* Most TW were satisfactory efficient in BOD5 and COD removal, and only partly efficient in N and P removal. The TW for industry were constructed for the treatment of food processing wastewater, characterized by high COD, BOD5, and ammonia nitrogen and for dye-rich textile wastewater. The results indicated that TW can be an appropriate technology for the treatment of wastewaters from those industries because the outflow parameters reached the prescribed legislation standards (Griessler Bulc & Ojsteršek, 2008; Zupančič Justin et al., 2009). Two pilot TW were constructed at the end of 2005 for the treatment of water from drinking water wells, polluted with pesticides (atrazine, metholaclor), and pathogens. The results showed the removal efficiency of *E.coli* from 130 to 500 bacteria/100 mL at the inflow to 0 to 3 bacteria/100 mL at the outflow from TW (Istenič et al., 2009). Regarding the pesticides removal, bentazon was reduced from 1.8 μg/L at the inflow to 0.06 μg/L at the outflow, metholaclor from 0.73 μg/L to <0.05 μg/L, and terbutylazine from 0.53 μg/L to <0.03 μg/L (LIMNOS Ltd., results not published). TW for highway run-off treatment showed 69 % removal efficiency for suspended solids, 97 % for settleable solids, 51 % for COD, 11 % for BOD5 and 80 % for Fe. Heavy metals (Cu, Zn, Cd, Ni and Pb) were below the legislation limits at the inflow with the reduction efficiency in the system of over 90 % while the concentrations of N and P showed a low level of nutrients for biological processes (Bulc and Sajn Slak, 2003). The TW for gray water was constructed in 2011. Preliminary data showed that gray water was mostly lost due to evapotranspiration. The TW for landfill leachate were constructed for the landfill sites that cover approximately 0.5 to 2 ha. With regard to the studied parameters, the performance of TW was not influenced by annual seasons, but primarily by precipitation. The reduction efficiency reached on average 50 % for NH4-N, BOD5 and COD (Griessler Bulc, 2006; Griessler Bulc & Zupančič Justin, 2007). The results proved that a TW can be considered a method appropriate for the leachate treatments of old waste dumps (Zupančič Justin et al., 2005).

*Case 1; Design:* The ET approach for the reclamation of a 1.5 ha landfill in south-eastern part of Slovenia consists of a landfill soil cover, which is densely planted with grasses and fast growing trees (poplars, willows) as a phytoremediation layer, a TW of 1,000 m2 with an average hydraulic load of 12 m3/d and an irrigation system. Landfill leachate is treated in the TW from where it is recycled on the landfill cover without outflow into the environment. Closed loop leachate circulation enables additional leachate treatment by assimilation of nutrients into the plant biomass and by mineralization processes of microbes in the soil layer. Fast growing trees allow the evapotranspiration of a considerable amount of leachate, while the excess percolates back into the landfill body and enables further biodegradation of deposited wastes. The results provided an environmentally and economically-viable solution, with large buffering capacity and simple in concept. The presented methods won international awards (2001 Lillehammer Award; 2008 Global Energy Award, Griessler Bulc

*Monitoring:* To evaluate plant response on leachate irrigation, a remote sensing of the canopy reflectance was performed by ground-based monitoring of vegetation indices of the phytoremediation system with a multispectral camera (Tetracam, USA). Images were taken in regular monthly intervals during one vegetation season, from April to October, after two

**6.1.4 Restorations of landfill sites** 

& Zupančič Justin, 2007).

years of leachate irrigation.

*Design:* The majority of watercourse revitalizations in Slovenia were carried out in the north-east part of the country. Revitalizations of short stretches of rivers and streams were designed in order to increase self-cleaning capacities of the streams in an intensive agricultural landscape and also in order to protect the natural population of otter. According to the data, the most continuous and viable population of *Eurasian otter* in Slovenia lives in the north-east of the country. Threats for otter in this area are degraded habitats due to the agro-operational works, including ameliorations and canalization of watercourses which took place in last decades. The results of non-sustainable management were among others the opening of corridors by removing tree canopies as well as riparian vegetation on watercourse banks (the shelter for otters disappeared, the living conditions for pray species worsened and consequently the food supply was reduced), the permeability of corridors had lowered and the risk for population fragmentation was higher. In order to protect and restore the otter population, ETs were implemented in

Ecosystem Technologies and Ecoremediation for Water Protection, Treatment and Reuse 213

from consumption to waste, which will result in a shortage of plant fertilizers in a near

In Slovenia ET are in a rise since 1989. Different ET have been applied, namely treatment wetlands, watercourse revitalization, vegetated drainage ditches, waste stabilization ponds, phytoremediation of landfill sites. Most common ET in Slovenia are treatment wetlands for municipal sewage followed by watercourses revitalization. A high number of treatment wetlands indicate the priority of local communities and the authorities to solve deficient wastewater treatment systems in the country. An important part of the research and development of ET in Slovenia was focused also on the restoration of landfill sites, where a closed water and pollutant loop was investigated and successfully implemented; however, the system is not yet successful in the market because the local governance and environmental managers are still focused on wastewater treatment. Due to gradual acceptance and implementation of ET in local environments there is still a long way to walk in order to

achieve sustainable society in terms of closing the loops of water and nutrient usage.

sewage

Treated water Average

125-750 1991-2008 Industrial - - Vrhovsek et al., 1996,

0.5-1 2009 2009-2011 Drinking water - - Data not published

10-100\* 2006-2008 2006- Surface water - - Vrhovsek et al., 2007;

agricultural run

off

inflow concentration

COD: 239 NH4-N: 496 TP: 8.9

NH4-N:281 TP:2.5

NH4-N:- TP: 0.4

NH4-N: 128 TP: 56

COD: 25 NH4-N: 0.3 TP: 0.3

NH4-N: 3.3 TP:2.07

NH4-N: 217 TP: 2.5

50 51 53

54 51 58

51 - 79

neg 7 3

67.2 neg-49 33

35 37 49

Efficiency Reference

2005

2009)

Slak, 2003


2011

Slak, 2009

Urbanc-Bercic et al., 1998, Sajn-Slak et al.,

Griessler-Bulc and Ojstersek, 2008; Zupancic-Justin et al.,

Griessler-Bulc, 2006; Griessler-Bulc and Zupancic-Justin, 2007

Griessler-Bulc and Sajn-

Griessler-Bulc and Sajn-Slak, 2007; Bulc et al., 2011, Griessler-Bulc and Krivograd-Klemenčič,

Griessler-Bulc and Sajn-

Sajn-Slak et al., 2005

Griessler-Bulc and Zupancic-Justin, 2007

Operation period

311-1000 1995-2004 1995-2004 Landfill leachate COD:979

85 2001 2001 Highway runoff COD:29

20 2011 2011 Grey water COD: 411

36 2000-2003 2001 Sewage COD:391

15000 2003-2005 2003-2011 Leachate, soil COD: 1257

20-90 2006 2006-2011 Surface water,

future. Closing the loops of wastewater treatment is therefore crucial.

Nr. Type Area m2 Year of

55\* Treatment wetland

9 Treatment wetland

8 Treatment wetland

1 Treatment wetland

1 Treatment wetland

2 Treatment wetland

2 Vegetated drainage ditch

12\* Watercourse revitalization

2 Phytoremediat ion

\*estimated numbers

Table 1. Data about ET in Slovenia

 Waste stabilization pond

construction

7.5-1500 1989-2011 1989-2011 Municipal

Goričko on short sections of watercourses and lakes of eight local communities. Different in-stream and stream bank features were implemented to attain a successful revitalization. Weirs with small pools were constructed in the channels to improve streambed substrate, slow down the flow velocity, retain water and provide proper fish passages. Artificial indentations as well as restored and protected indentations contribute to better water habitats diversity. The passages for otters under the bridges were implemented which enabled otters to pass the roads safely. New vegetation zones (riparian wetlands and constructed wetlands) prevent erosion, provide buffer and better connectivity between terrestrial and aquatic ecosystems (Griessler Bulc & Šajn-Slak, 2009). The revitalization measures were also widely accepted by the local population, satisfied by the re-gained natural appearance of the streams and water murmur.

Fig. 4. Schematic evolution of river revitalization (source: LIMNOS Ltd.)
