Comparative evaluation of river chemical status based on WFD methodology and CCME water quality index.

The Water Framework Directive (WFD) methodology, proposed by the Ministry of Environment and Energy of Greece (WFD-MEEG), and the Canadian Council of Ministers of Environment Water Quality Index (CCME-WQI) are comparatively applied to evaluate the chemical status of a major transboundary river. Water quality parameters were monitored at 11 sites along the main stream of the river and its main tributaries, and at five sites in the reservoirs, on a monthly frequency, in the period from May 2008 to May 2009. Water temperature (T), dissolved oxygen (DO), pH, and electrical conductivity (EC) were measured in-situ, while water samples were collected for the determination of total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrite-, nitrate- and ammonium-nitrogen, total Kjeldahl nitrogen (TKN), ortho-phosphates (OP), total phosphorus (TP), and chlorophyll-a (Chl-a). The water samples were also analyzed for the determination of seven heavy metals (i.e., Cd, Pb, Hg, Ni, Cr, Cu, Zn) and 33 priority substances, as listed in Annex II of EU Directive 2008/105/EC. The results showed that the physicochemical parameters (i.e., T, DO, pH, EC, inorganic nitrogen, TKN, OP, TP, TSS, and Chl-a) were within the natural range. The mean concentration of the measured heavy metals did not exceed the limits set by WHO (2003, 2017) for drinking water. Regarding the priority substances, some of them (i.e., anthracene, fluoranthene, and polyaromatic hydrocarbons) were measured in various stations at higher concentrations than the Annual Average Environmental Quality Standards (AA-EQS). Based on the WFD-MEEG methodology, the river water was in the 'good' quality class, while according to CCME-WQI the river quality ranged from 'marginal' to 'good' category. It seems that CCME-WQI is stricter than WFD-MEEG but could be a WQI appropriate for use.

On-site treatment of domestic wastewater using a small-scale horizontal subsurface flow constructed wetland.

A small-scale horizontal subsurface flow constructed wetland, located in North Greece, was designed and constructed to treat wastewater from a single-family residence. A three-year monitoring program was undertaken to evaluate the performance of this system. The monitoring campaigns were organized every 7 days. Water quality samples were collected at the inlet, at intermediate points (i.e. at the end of each treatment stage) and at the outlet of the system. Temperature, electrical conductivity, pH and DO were measured in-situ with the use of appropriate instruments at the same points of water sample collection. Water samples were analyzed for BOD, COD, TKN, ammonia, nitrate, nitrite, total phosphorus (TP), ortho-phosphate (OP), total suspended solids (TSS) and total coliforms (TC). Mean removal efficiencies for the monitoring period were: 86.5% for BOD, 84.6% for COD, 83.7% for TKN, 82.2% for ammonia, 63.1% for OP, 63.3% for TP, 79.3% for TSS and 99.9% for TC. Furthermore, based on statistical testing, TKN, ammonia and TP removal efficiencies showed dependence on temperature. The paper presents facility description, study details and monitoring results. The study shows that the use of constructed wetlands in wastewater treatment is a good option for single-family residences in rural areas.

Constructed wetlands for wastewater and activated sludge treatment in north Greece: a review.

Constructed wetlands used for the treatment of urban, industrial and agricultural wastewater have become very popular treatment systems all over the world. In Greece, these systems are not very common, although the climate is favourable for their use. During recent years, there have been several attempts for the implementation of these systems in Greece, which include, among others, pilot-scale systems used for research, and full-scale systems designed and/or constructed to serve settlements or families. The purpose of this paper is the presentation of systems operating in Northern Greece, which have been studied by the Laboratory of Ecological Engineering and Technology of Democritus University of Thrace and others. A comparison is made of different system types, and the effect of various design and operational parameters is presented. Current research shows the good and continuous performance of these systems.

Performance and cost comparison of a FWS and a VSF constructed wetland system.

Two constructed wetland systems, treating domestic wastewater, are compared in terms of performance and costs. One is a free water surface (FWS) wetland system located in Pompia, Crete, south Greece, and the other one is a vertical subsurface flow (VSF) wetland system located in Comati, Chalkidiki, north Greece. The FWS system is designed for 1200 p.e. Its construction cost was Euro 305,000, and the capital, operation and maintenance cost was Euro 22.07 p.e.(-1) yr(-1) or Euro 0.50 m(-3) of influent. The VSF system is designed for 1000 p.e. Its construction cost was Euro 410,850, and the capital, operation and maintenance cost was Euro 36.81 p.e.(-1) yr(-1) or Euro 0.56 m(-3) of influent. Both systems achieved high removal rates for BOD5, COD, TSS, TKN, phosphorus, TC, and FC, which makes them ideal for small communities in the Mediterranean region.