Demetris Lekkas

• PhD in Hydrology
• Professor (Associate) at University of the Aegean

The main aim of this paper is to address the available literature on the issue of controlling the composition of polyhydroxyalkanoates (PHAs) during their production from organic wastes and if possible, provide a complete strategy to achieve consistent composition. Improvement in the handling of single-use packaging can result in tangible results i...

The degradation of high-density polyethylene (HDPE) in marine environments was investigated under various weathering conditions. HDPE debris were collected from coastal areas near Korinthos, Greece which had been exposed to marine conditions for durations ranging from a few months to several decades; they were analysed alongside with laboratory-man...

In an attempt to increase our understanding of bio-based consumption behavior, this study examines antecedents and consequences of consumer satisfaction associated with three different bio-based products: (i) bio-based wall paint, (ii) bio-based household cleaning detergent, and (iii) a kitchen chair made of biosynthetic material. The proposed stru...

Climate change and the related greenhouse gas (GHG) emissions are an evident threat to Europe and the world and have been at the forefront of environmental policy for decades. Carbon footprint calculators provide a valuable approach when it comes to informing people about GHGs and specifically to CO2 equivalent (CO2-eq). These calculators estimate...

The maritime industry is addressing environmental issues, and “cold ironing” offers a promising solution. This method involves supplying ships at port with energy, reducing fossil fuel dependence and emissions, and aiding in global climate change efforts. It is especially important for islands like Lesvos, which suffer from high energy costs and en...

Food waste (FW) has become a global concern, with an estimated 1.3 billion tonnes lost annually, costing about $1 trillion. Environmental and social consequences of FW are significant, contributing to 6% of European Unions’ greenhouse gasemissions and affecting global food security. FW occurs is a complex issue occurring at various stages of the fo...

This research focuses on the management of food waste in small communities such as the one at the Reception and Identification Center (RIC) of Kara Tepe in Lesvos (Greece), using the method of home composting. To understand production patterns and possible variations of the characteristics of food residues, a sampling methodology was designed for o...

The maritime sector, grapples with environmental challenges, but the adoption of "cold ironing" emerges as a promising solution, signifying a shift toward sustainability by providing energy to ships at port, reducing reliance on fossil fuels, and significantly lowering emissions, contributing to global climate change efforts. This transition toward...

This study investigates the effect of nine consumer barriers to bio-based food products in shaping purchase intentions. A structural model is developed to assess: (i) the influence of prior experience with bio-based products and demographics on the perceived impact of the consumption barriers, (ii) how these nine barriers affect consumers' interest...

The linear economy of today's society conflicts with many environmental, social, and economic challenges. Therefore, the implementation of the Circular Economy model is prioritized by policymakers and the research community. The European Union is in accord with the smooth transition towards a Circular Economy through the Circular Economy Strategy,...

Short sea shipping involves transporting passengers and cargo between European ports and coastal countries bordering Europe on enclosed seas. Challenges include aging fleets and environmental concerns, but efforts to reduce emissions are in progress through the use of low-sulfur fuels, hybrid and electric vessels, and improved energy efficiency. Th...

Public spaces underwent a notable shift in their acoustic profile during the societal restrictions resulting from the COVID-19 pandemic. A silver lining emerged from this global crisis, with noticeable improvements in public acoustic environments due to reduced noise levels resulting from restricted mobility. This research focuses on the acoustic e...

In recent years, the growing popularity of plastic materials made from renewable biomass sources has prompted research on stakeholder views. This is because the circularity and decoupling credentials producing such materials can be substantial but also bring to the forefront pressing questions around public receptiveness and support. To this regard...

The food production industry on Lesvos island generates a significant amount of liquid biowaste, including olive mill wastewater, cheese whey wastewater, and wine sludge. Co-utilizing different food waste sources supports the Circular Economy concept and offers alternative routes in the waste valorization field. Hydrothermal treatment was applied t...

Environmental obligations of scientists, engineers and members of the research community have evolved further than the quantifiable control of emissions and waste of production. The environmental consciousness of communities as well as individual responsibility for the development of sustainable waste management strategies increased in demand, from...

Marine plastic pollution is a growing environmental concern, with plastic debris in the ocean having negative impacts on marine life and human health. One of the major challenges in addressing this problem is the slow degradation rate of plastics in the marine environment. In this study, the degradation of high-density polyethylene (HDPE), being ex...

Environmental noise is a global problem with multiscale consequences, affecting human well-being, environmental health and business efficiency. Several tourist accommodations aiming towards a more competitive and profitable business, produce the by-product of noise thus resulting in a higher noise footprint. The aim of this research is to propose a...

This study aims to present an overview of incorporating the Water Framework Directive into Italian law through Law 152/06. Subsequently, it will focus on a case study involving 34 rivers in the Salerno Province, utilizing data obtained from ARPA Campania. This work analyses the macro pollution indicators of the observed rivers using two aggregated...

The citizen’s carbon footprint is affected by various factors, but mostly by electricity consumption, daily transportation, travelling habits, as well as municipal solid waste management, a critical factor that is not frequently incorporated in carbon footprint estimations. This paper proposes a new carbon footprint calculator, the Carbon Footprint...

There are several sustainability issues that the linear economy of today's society cannot adequately tackle (i.e. resource depletion, waste treatment, etc.). As a result, the scientific community and policymakers give high priority to the implementation of the circular economy concept. The sustainable development goals of the United Nations are in...

Short sea shipping refers to the transportation of passengers and cargo between ports in Europe or coastal countries bordering Europe on enclosed seas. Aging fleets and environmental concerns pose challenges, but efforts are underway to reduce emissions through the adoption of low-sulfur fuels, hybrid and electric vessels, and improved energy effic...

Potato is the most popular non-grain food crop in the world, known for its high yield, water efficiency and nutritional 30 value and consequently it can play a vital role in food security. Yet, the examination of the environmental impact 31 associated with potato production represents a gap in the field of agricultural production. The purpose of th...

Biowaste management is at the center of attention in recent years due to the increased focus on Circular Economy practices. Lesvos has numerous food processing facilities and olive mills, and therefore Olive Mill Wastewater (OMWW) is a wastewater stream that requires attention. In this study, a holistic experimental set-up that combines aerobic and...

Biowaste management is in the center of attention in recent years, due to the increased focus on Circular Economy practices. Recent management solutions promote exploration for small and medium scale processing and monitoring practices. In this context, two pathways of biowaste valorization are analyzed: composting and anaerobic digestion. This stu...

The concepts of noise and quietness are multidimensional, contradictive and retain a degree of fuzziness. Their notion expands between the physical dimension of sound to a phenomenological/perceptual construct. The perception of noise as a sound of high-intensity or as an unwanted sound has shaped the concept of quietness as an urban sound design g...

The linear economy of today’s society conflicts with many environmental, social, and economic challenges (i.e. resource depletion, waste treatment, emissions, etc.). Therefore, the implementation of the Circular Economy (CE) model is prioritized by policymakers and the research community. The European Union is in accord with the smooth transition t...

This work examines the continuous addition (5 g/L) of conductive granular activated carbon (GAC) in an integrated pilot-scale unit containing an anaerobic digester (180 L) and an aerobic submerged membrane bioreactor (1600 L) connected in series for the treatment of agro-industrial wastewater. Biogas production increased by 32% after the addition o...

This study investigates structural linkages of perceived product quality, value, price, innovation, quality, risk, brand image, marketing awareness and labelling on customer satisfaction and loyalty towards bio-based products usage. The study employs the structural equation modelling technique for data analysis across a sample of 100 Greek consumer...

This study examines consumer preferences for bio-based products. Drawing from a sample of Greek consumers ( n = 533) and the use of self-reported scales, we assess the effects of individuals’ characteristics such as innovativeness, trust in science and technology, environmental concern, and previous experience with bio-products on consumer preferen...

The circular economy paradigm can be beneficial for urban sustainability by eliminating waste and pollution, by circulating products and materials and by regenerating nature. Furthermore , under an urban circular development scheme, environmental noise can be designed out. The current noise control policies and actions, undertaken at a source-mediu...

The standardized precipitation index (SPI) is used for characterizing and predicting meteorological droughts on a range of time scales. However, in forecasting applications, when SPI is computed on the entire available dataset, prior to model-validation, significant biases are introduced, especially under changing climatic conditions. In this paper...

The treatment and disposal of organic household and industrial waste is a global issue. Several environmental, social, and economic problems are associated with current waste management practices. Composting biowaste is a financially affordable and easy-to-use method, while compost, the final product, can improve various soil properties. In this st...

Purpose: The acquisition of reliable data on Municipal Solid Waste (MSW) composition is very important for the development of environmentally sound, sustainable and economically viable integrated waste management systems. However, no standardized universally accepted waste characterization protocol has been developed, as there are various methodolo...

There is not a universal method for assessing the quality of composts. This can be mainly attributed to the fact that composts are assessed by means of multiple measured parameters. For the case of composts, several parameters are optimal not necessarily if maximized or minimized but ideally when they are within a specific range of values. The comm...

The North Aegean Islands of Chios and Lesvos set recycling goals for organic residues from Municipal Solid Wastes (MSW). Both islands, in line with the National and Regional Plans for Municipal Waste Management, are discussing the approach of mechanical-biological stabilization MSW in combination with separated collection of biowastes and municipal...

Generalized linear models (GLMs) are popular tools for simulating daily rainfall series. However, the application of GLMs in drought-prone areas is challenging, as there is inconsistency in rainfall data during long and irregular periods. The majority of studies include regions where rainfall is well distributed during the year indicating the capab...

An investigation into the occurrence of priority substances regulated by 2000/60/EC Water Framework Directive and 2008/105/EC Directive was conducted for a period of one year in the surface water sources supplying the water treatment plants (WTPs) of Athens and in the raw water of WTPs. Samples from four reservoirs and four water treatment plants o...

Hotel sector causes significant environmental stress in both natural and built up areas due to their consumption of water and energy. In addition, the production of large volumes of liquid and solid waste results in a significant environmental footprint. The use of water and energy by hotels is strongly linked (e.g. energy is consumed for hot water...

Prediction of runoff response in ungauged catchments has been one of the key issues in water science. Despite the considerable effort, the hydrologic community has devoted over the past decade, there is still need to develop robust frameworks capable of representing the dynamic behaviours of catchment processes (e.g. streamflow). Runoff prediction...

The objective of this pilot study was to evaluate the performance of Powdered Activated Carbon (PAC) for the removal of individual trihalomethanes (THMs) from chlorinated drinking water, Athens, Greece. The pilot treatment facility was located at the Water Treatment Plant of EYDAP (Athens Water Supply and Sewerage Company) in Galatsi, Athens, and c...

For many years the water supply system of Athens in Greece has been disinfected mainly by chlorination. A consequence of chlorination is the formation of trihalomethanes (THMs). A survey was conducted to determine their levels in the Athens water supply system over a period of time. A multiple regression model for THM formation was generated for pr...

The hydrologic community has recently focused substantial attention on ungauged or poorly gauged catchments, since hydrological prediction under these conditions is highly uncertain, but represents the majority of practical applications. Catchments in Greece are usually ungauged, due to resource constrains, whilst in gauged areas the period of reco...

The concentrations of nine emerging contaminants, including pharmaceutically active compounds (PhACs) (ibuprofen, IBF; naproxen, NPX; diclofenac, DCF; ketoprofen, KFN) and endocrine disrupting chemicals (triclosan, TCS; bisphenol, BPA; nonylphenol, NP; nonylphenol monoethoxylate, NP1EO; nonylphenol diethoxylate, NP2EO), were determined in wastewate...

The objective of this study was to investigate the fate of selected endocrine disrupting compounds (EDCs) and non-steroidal anti-inflammatory drugs (NSAIDs) in lab-scale anaerobic digesters, operating under single stage and two-stage thermophilic and mesophiilic anaerobic conditions. Within the context of this study, the performance of all digestio...

: The purpose of this research was to evaluate the effect of low power sonolysis sludge pre-treatment on subsequent anaerobic digestion (AD) and to evaluate AD performance under different temperatures (37 o C, 55 o C), SRT values (8, 12 and 20 days) and operational modes (one stage AD and two-stage thermophilic and mesophilic AD). The impact of eac...

Drought is a natural hazard that can affect regions for months or years resulting to both environmental and socio-economic impacts. Different drought definitions (meteorological, agricultural, hydrological and socioeconomic) can be found in literature that can be linked to spatial and temporal characteristics of an event as well as to the correspon...

Artificial neural networks (ANNs) are being used increasingly to predict water variables. This study offers an alternative approach to quantify the relationship between time of chlorination in potable water (due to convectional treatment procedure) and chlorination by-products concentration (expressed as carbon and bromine) with an ANN model, i.e.,...

Current practices for the efficient use and management of water resources are based on the conjunctive application of water supply and demand measures. Even though options for the augmentation of water supply are widely analysed and assessed, water demand management remains an open field for study, as it is highly dependent on the socio-economic fe...

Chlorine was accepted as an effective disinfectant for drinking water in early 1900s. Because of chlorination, chlorine has dramatically reduced the incidence of waterborne diseases. An unwanted side effect is the formation of harmful by-products upon chlorination. The most significant group of disinfection by-products formed during chlorination is...

This article presents an analytical method based on solid-phase extraction (SPE) and gas chromatography coupled with mass spectrometry for the simultaneous determination of the most frequently used acidic pharmaceutical residues, ibuprofen, diclofenac, naproxen and ketoprofen (KFN), and phenolic endocrine disruptors, bisphenol (BPA), triclosan (TCS...

An econometric model has been developed that represents the cost structure of water supply and waste water treatment in an urban area. This paper proposes a method to capture the fi nancial characteristics of the underlying organisation and addresses the steps and the conceptualisation in order to create a cost structure for municipal water utiliti...

Laboratory studies were conducted to determine the sorption and desorption behaviour of two commonly used organophosphorus pesticides dimethoate and fenthion, which are widely used in the studied area to treat the olivetrees. Three Greek soils from the region of Mytilene island (denoted M, KT and P) which differed with respect to pH (pH 5.45–6.90),...

An analytical method for the simultaneous determination of the four most detected non-steroidal anti-inflammatory drugs (NSAIDs) in wastewater, namely ibuprofen (IBF), naproxen (NPX), diclofenac (DFC) and ketoprofen (KFN), was developed based on gas chromatography-mass spectrometry (GC-MS). Extraction from wastewater samples was performed by solid-...

The objective of this pilot-study is to evaluate the Granular Activated Carbon (GAC) performance for the removal of specific disinfection by-products (DBPs), trihalomethanes (THMs) and haloacetic acids (HAAs), from Athens drinking water. For this purpose, a GAC pilot filter-adsorber was operated in Galatsi WTP, Athens, for 235 days, until the GAC r...

The relationship between catchment size and streamflow magnitude is a well known hydrological theory and is usually used for prediction at ungauged basins (PUB). However, the nonlinear behavior of this relationship generates a number of problems when used for flood peak prediction for design purposes due to increased uncertainty. In this study, art...

Salt, the world's best-known mineral, is the chemical substance most related to human civilization history. Apart from his significance for the creation of life on the planet it has been used as main commodity for centuries. Man produces salt by solar evaporation since the dawn of human civilization. Nevertheless, recognition of the unique coastal...

The traditional approach to urban water management is primarily based on a supply-oriented approach, where water follows a one-way path from supply to a single use, to treatment and then discharged to the environment. The wide acknowledgement of the need to shift towards more sustainable practices has led to the recognition that demand is multi-fac...

Forecasting river flow is important to water resources management and planning. Four artificial neural network (ANN) models were developed and compared in order to forecast river flow in the River Trent, UK. The first two are feed-forward networks and were trained with back-propagation and cascade-correlation algorithms; the third is an adaptive li...

The toxic effects of triclosan (TCS) and nonylphenol (4-n-NP) on activated sludge heterotrophic and autotrophic microorganisms were evaluated. Toxicity experiments with specific oxygen uptake rate (SOUR) and ammonia uptake rate (AUR) revealed that TCS was much more toxic to heterotrophic and autotrophic microorganisms than 4-n-NP. In experiments wi...

The aim of this paper is to elaborate strategies, methodologies and techniques for integrated water resource management within the philosophy of the EC Water Framework Directive (2000/60/EC) for the trans-boundary river basin of Evros which is shared by two EU (Greece, Bulgaria) and an EU-candidate country (Turkey). With the recent comer EU Member...

The presence of organic compounds in bottled waters available in the Greek market and their fate when the representative samples exposed at different conditions were the main purposes of this study. The determination of the organic compounds was performed by gas chromatography–mass spectrometry techniques. Disinfection by-products compounds, such a...

The occurrence of five endocrine-disrupting compounds (EDCs), namely 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), triclosan (TCS) and bisphenol A (BPA), was assessed in the raw, treated wastewater and sewage sludge of eight sewage treatment plants (STPs) in Greece. The analytes were extracted by so...

The goal of the current review is to present and analyze the known information proposed and discussed the last few years about UFP and their possible health effects. It includes references from 1992 to 2008. It also includes references from some fundamental studies in the 1970's and 1980's. The review and analysis of the health hazards induced by u...

EXTENDED ABSTRACT The traditional approach to urban water management is primarily based on a supply-oriented approach, where water follows a one-way path from supply to a single use, to treatment and then discharged to the environment. The wide acknowledgement of the need to shift towards more sustainable practices has led to the recognition that d...

AWSC (Athens Water Supply and Sewerage Company) uses chlorine as an acceptable disinfectant. An unwanted side effect of chlorination is the formation of by-products. One of the most significant groups of disinfection by-products is the trihalomethanes. Water companies have to keep their concentration levels lower than the limits that the E.U. Direc...

The purpose of this research was to study the fate and toxicity of triclosan (TCS) in activated sludge systems and to investigate the role of biodegradation and sorption on its removal. Two continuous-flow activated sludge systems were used; one system was used as a control, while the other received TCS concentrations equal to 0.5 and 2mgl(-1). At...

Organotin compounds belong to the priority list of substances regulated by 76/464/EEC Directive, as well as by 2000/60/EC Water Framework Directive, because they pose considerable risks to the environment and human health. They are the most commonly used organometallic compounds with estimated global amount produced 50,000 tons per year. Therefore,...

Aquatic humic substances are amorphous organic macromolecules and precursors of mutagens formed on chlorination of raw water. Their isolation from River Mornos and Lake Yliki (primary reservoirs of Athens Water Supply and Sewerage Company) using columns of XAD-8 and IR-120 resins is performed in order to study their structural differences among res...

A rapid multiresidue method has been developed for the analysis of 17 organochlorine pesticides (OCPs) (α-HCH, γ-HCH, β-HCH, δ-HCH, aldrin, heptachlor epoxide, endosulfan I, 4,4-DDE, dieldrin, endrin, 4,4-DDD, endosulfan II, 4,4-DDT, endrin aldehyde, endosulfan sulfate, methoxychlor and endrin ketone) in marine sediments. The method is based on the...

A simple screening method for the determination of toluene-extractable organotin compounds in water samples was developed. Organotins [tributyl tin (TBT), triphenyltin (TPhT) and dibutyl tin (DBT)] were extracted from 2 1 of water sample with 10 mL of toluene in the presence of 2.5% (v/v) CH3COOH and 1.2% (w/w) NaCl. Aliquots of 240 μl of the tolue...

Polycyclic aromatic hydrocarbons (PAHs) as well as nonylphenol (NP) and octylphenol (OP) are substances of major environmental concern because of their adverse health effects on organisms, including endocrine disrupting activity. Seven PAHs, NP and OP have been included in the priority list of substances regulated by 2000/60/EC Water Framework Dire...

The objective of this pilot study was to evaluate the performance of a GAC postfilter-adsorber for the removal from the drinking water of Athens, Greece, of the two main groups of chlorination by-products, trihalomethanes (THMs) and haloacetic acids (HAAs), as well as of dissolved organic carbon (DOC). The analyses performed during the whole operat...

The presence of organotin (OT) compounds was investigated in coastal areas (10 stations), wastewater treatment systems (six stations), rivers (19 stations) and lakes (12 stations) throughout Greece, in three sampling campaigns organized between October 1998 and September 1999. A screening method for the determination of toluene extractable organoti...

The presence of organotin (OT) compounds was investigated in coastal areas (10 stations), wastewater treatment systems (six stations), rivers (19 stations) and lakes (12 stations) throughout Greece, in three sampling campaigns organized between October 1998 and September 1999. A screening method for the determination of toluene extractable organoti...

An integrated analytical method for the simultaneous determination of 4-n-nonylphenol (4-n-NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), bisphenol A (BPA) and triclosan (TCS) in wastewater (dissolved and particulate phase) and sewage sludge was developed based on gas chromatography-mass spectrometry. Chromatographic ana...