Petros Samaras

International Hellenic University · Deaprtment of Food Science and Technology

This study investigated the effect of light intensity on the growth and nutrient uptake of Chlorella sorokiniana cultivated in nitrogen-rich anaerobic digestion wastewater. Three light intensities (20, 68, and 162 µmol m⁻2 s⁻1) were applied over a 30-day period with a 16:8 h light–dark photoperiod. The goal was to understand how light affects bioma...

In the current study, the cultivation of microalgae on wastewater-based substrates is investigated for an effective natural wastewater treatment that also generates biofuels and value-added products beneficial to human health. Additionally, the health of ecosystems can be evaluated via microalgae. The utilization of microalgae as bioindicators, bio...

Microalgae offer a promising solution for efficiently treating high-nitrogen wastewater and recovering valuable nutrients. To optimize microalgae growth and nutrient assimilation, case-dependent studies are essential to demonstrate the process’s potential. This study aimed to evaluate the treatment capacity of high-nitrogen anaerobic digestion effl...

Access to safe drinking water is critical to health and development issues, and drinking behavior reflects awareness of health and water quality. In this paper, a study on the observations of trends in water consumption was conducted. hypotheses were formulated based on: water consumption, drinking tap water, awareness on drinking water, and Willin...

Wastewater treatment plants play a significant role in minimizing environmental pollution by treating wastewater and reducing the release of contaminants into the environment. However, their operation can still have an environmental footprint. Therefore, Life Cycle Assessment (LCA) of wastewater treatment provides a comprehensive framework to quant...

Moving bed biofilm reactor combined with membrane bioreactor (MBBR-MBR) constitute a highly effective wastewater treatment technology. The aim of this research work was to study the effect of commercial K1 biocarriers (MBBR-MBR K1 unit) and 3D-printed biocarriers fabricated from 13X and Halloysite (MBBR-MBR 13X-H unit), on the efficiency and the fo...

The current study investigated the performance of a moving bed biofilm reactor (MBBR), when adding 3D-printed biocarriers fabricated with 13X and bentonite (MBBR 3D), when using K1 commercial biocarriers (MBBR K1) and when not adding biocarriers at all (control MBBR). For the evaluation of the MBBR efficiency, various physicochemical parameters wer...

For this research, a comparative evaluation was performed in which the addition of 3D-printed biocarriers fabricated with 13X and Halloysite (13Χ-Η) and commercial Kaldnes K1 biocarriers were evaluated as opposed to the non addition of biocarriers in a semi-pilot scale MBBR-MBR unit. For the evaluation of the MBBR-MBR efficiency, various physicoche...

In the present work, a comparative evaluation of an MBBR unit performance was carried out for the following cases: when adding 3D-printed biocarriers fabricated with 13X and bentonite, when using K1 commercial biocarriers and when not adding biocarriers at all. For the evaluation of the MBBR efficiency, various physicochemical parameters were measu...

Background: Aerobic or anaerobic digestion is involved in treating agricultural and municipal waste, and the addition of biocarriers has been proven to improve them further. We synthesized novel biocarriers utilizing zeolites and different inorganic binders and compared their efficiency with commercially available biocarriers in aerobic and anaerob...

The aim of this paper was to evaluate the characteristics and the energy potential for the methane production of fine screenings collected from the primary stage of a municipal wastewater treatment plant, and assess the impact on the properties and the oxygen demand of the aqueous effluents downstream from the sieves. Commercial filter bags with si...

Four microalgae species were evaluated for their bioremediation capacity of anaerobic digestion effluent (ADE) rich in ammonium nitrogen, derived from a biogas plant. Chlorella vulgaris, Chlorella sorokiniana, Desmodesmus communis and Stichococcus sp. were examined for their nutrient assimilation efficiency, biomass production and composition throu...

Concrete sewer pipes can be corroded by the biogenic sulfuric acid (H2SO4) generated from microbiological activities in a process called biocorrosion or microbiologically induced corrosion (MIC). In this study, inhibitors that can reduce Acidithiobacillus thiooxidans growth and thus may reduce the accumulation of biofilm components responsible for...

Ammonia accumulation in biogas plants reactors is becoming more frequently encountered, resulting in reduced methane (CH4) production. Ammonia toxicity occurs when N-rich substrates represent a significant part of the biogas plant’s feedstock. The aim of this study was to develop an estimation method for the effect of ammonia toxicity on the CH4 pr...

A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtr...

Investigating societal and environmental correlations aims at encouraging public participation and active involvement to facilitate understanding and strengthen social acceptance of emerging technologies for improving human health and well-being especially during pandemics. In this context, studying social inputs in relation to critical environment...

Clean water is an essential resource for life, and its demand is continuously increasing with the rapid growth in population, while the freshwater reserves are also depleting. A large amount of wastewater is released by different industries, which is affecting the environment as well as polluting the freshwater reserves. Recycling and treatment of...

This is the first study that examines the effect of operating conditions on fouling of Membrane Bio-Reactors (MBRs), which treat municipal wastewater in field conditions, with specific regard to the controlled development of filamentous microorganisms (or filaments). The novelty of the present work is extended to minimize the dissolved oxygen (DO)...

Wastewater treatment plants have been traditionally developed for the aerobic degradation of effluent organic matter, and are associated with high energy consumption. The adoption of sustainable development targets favors the utilization of every available energy source, and the current work aims at the identification of biomethane potential from n...

Simple and low-cost field systems called biobeds have been successfully developed in Sweden to reduce the environmental pollution caused by pesticides. Although these systems have been efficiently used for the treatment of a broad range of wastewaters worldwide, however, their utilization for olive oil mill wastewaters (ΟMWW) treatment is limited....

Concrete sewer pipes can be deteriorated by sulfuric acid (H2SO4), which is created by the oxidation of hydrogen sulfide in the presence of certain bacteria inside the sewers. This process is called biocorrosion. In this paper, H2SO4 (i.e., chemical, non-biogenic) was used to study acid attack on concrete samples. The authors conducted experiments...

Membrane bioreactor (MBR) systems are connected to several advantages compared to the conventional activated sludge (CAS) units. This work aims to the examination of the life cycle environmental impact of an MBR against a CAS unit when treating municipal wastewater with similar influent loading (BOD = 400 mg/L) and giving similar high-quality efflu...

Thirteen bacterial isolates from a bioreactor treating a mixture of municipal and molasses wastewater were investigated for their potential to degrade and decolorize melanoidins. All isolates were initially screened for manganese peroxidase activity and growth potential in the presence of four synthetic melanoidins solutions at concentrations rangi...

The biological activity occurring in urban sewerage systems usually leads to the (biogenic) corrosion of pipe infrastructure. Anti-corrosion coating technology was developed in an effort to protect sewer pipes from degradation. This study evaluates a new class of relatively low-cost magnesium hydroxide-based coatings, regarding their ability to adh...

The investigation of environmental and social inputs in relation to health has lately attracted notable attention. In the process for discovering correlations between environment, society and health, public participation is a widely used approach. In this framework, most state-of-the-art methodologies often lack transparency and interpretability, b...

Membrane fouling still remains a drawback for membrane bioreactors; there is nevertheless a natural promising solution which is the growth of filamentous microorganisms in moderate concentrations. In this project, an innovative 25 L membrane bioreactor is used, consisting of two aerated tanks and a membrane tank. The first tank is supplied with hig...

Wastewater treatment, as a crucial component of the urban water environment, consists of several energy-consumptive stages, therefore efficiency and energy savings measures are essential to maintain them as environmentally sustainable and economically viable. Operational and technical data from WWTPs in Greece have been collected as well as a sampl...

Membrane fouling investigations in membrane bioreactors (MBRs) are a top research issue. The aim of this work is to study the combined effect of colloids and soluble microbial products (SMPs) on membrane fouling. Two lab-pilot MBRs were investigated for treating two types of wastewater (wwt), synthetic and domestic. Transmembrane pressure (TMP), SM...

The changing role of the municipal water and wastewater authorities, together with the need for a sustainable maintenance treatment in the sewer systems, have been the catalysts for the integration of technical and financial information into asset management systems. This paper presents results from a cost-comparative analysis focusing on an annuit...

Tanning involves the processing of raw hides and skins through chemical reactions and mechanical methods to produce leather for the manufacturing of various products. Conventional methods of pre-tanning and tanning in the leather industry result to the production of enormous volumes of toxic liquid, solid and gaseous waste streams, and to the consu...

This paper is intended to review the current practices and challenges regarding the corrosion of the Greek sewer systems with an emphasis on biocorrosion and to provide recommendations to avoid it. The authors followed a holistic approach, which included survey data obtained by local authorities serving more than 50% of the total country’s populati...

Social acceptance of water quality in urban areas depends on the perception and awareness of the stakeholders and the wider public. Moreover, the significance of social trust in stakeholders appears to be an influential factor affecting social support of water quality. However, efforts on understanding, communicating and engaging with the public an...

In this study, a comprehensive literature review is conducted with regard to recent advances in using recycled fly ashes as alternative and cost-effective reagents than as wastes in the advanced oxidation of wastewaters. Fly ashes are powdery solid residues that are produced in enormous quantities in coal/lignite-fed power stations and also from wa...

Social acceptance of water quality in urban areas depends on the perception and awareness of the stakeholders and the wider public. Moreover, the significance of social trust in stakeholders appears to be an influential factor affecting social support of water quality. However, efforts on understanding, communicating and engaging with the wider pub...

Membrane biofouling, due to Soluble Microbial Products (SMP) and Extracellular Polymeric Substances (EPS) deposition, results in reduction of the performance of Membrane Bioreactors (MBRs). However, recently, a new method of biofouling control has been developed, utilizing the interference of the bacterial inter- and intra-species' communication. B...

The treatment, management, recovery and disposal of industrial and hazardous waste are common concerns worldwide. In Greece, such types of wastes are considered as an integral part of the immediate priorities and strategies of both the National Hazardous Waste Management Plan (NHWMP) and the respective Regional Waste Management Plans. According to...

This study aims to better clarify the mechanism of MBR membrane fouling, since it remains ambiguous due to its high complexity. The fouling mechanism was studied during long-term lab-scale MBR experiments in a hydrophilic and a hydrophobic membrane and was evaluated according to the trans-membrane pressure (TMP) profile, the size of colloid particl...

Membrane bioreactors (MBR) constitute an advanced wastewater treatment technology over conventional activated sludge processes, however, membrane fouling remains the basic obstacle preventing their universal application. Extended research has been carried out on this issue but an optimal solution has not yet been found. This research proposes an in...

The objectives of this study were to investigate the composition of activated sludge biofilms and floes in a sequential batch reactor (SBR) and in a sequential biofilm batch reactor (SBBR). and to evaluate the role of the extracellular polymeric substances produced m the reactors in comparison with the respective treatment efficiency of domestic wa...

The treatment of molasses wastewater, by a combined microalgae-activated sludge process, for the simultaneous organics and total nitrogen reduction, was examined. Further enhancement of the performance of the combined process was accomplished, by means of biofilm carriers or electrocoagulation. A LED light tube was immersed into the reactor tank ai...

The aim of this work was the examination of the treatment potential of molasses wastewater, by the utilization of activated sludge and microalgae.The experimental systems used included an activated sludge sequencing batch bioreactor (SBR) operating in 12-h subsequent cycles, and a similar photo-bioreactor, aiming to favor microalgae growth. The mic...

BACKGROUND The baker's yeast industry is a major market and due to the intensified production large quantities of waste are generated. Wastewater from the baker's yeast industry with high content of molasses was treated anaerobically in an upflow anaerobic sludge blanket (UASB) reactor for the production of methane (CH4). RESULTS The molasses wast...

This work aims to identify the potential biomass resources produced in the area of the Central Macedonia Region, in Northern Greece, in order to contribute to the efforts to achieve national targets for renewable energy sources. Specific objectives included the evaluation of the biomass amounts in each regional unit, the measurement of their charac...

The ability of selected manganese peroxidase (MnP) yeast strains, isolated from the mixed liquor of an activated sludge bioreactor treating melanoidins wastewater, was investigated in this work, aiming to examine the degradation potential of melanoidins, in the presence or absence of nutrients. Ten yeast strains were initially isolated from the mix...

Utilization of constructed wetlands for the last two decades indicates significant progress took place on the operation and efficiency of constructed wetland systems including free water surface constructed wetlands and sub-surface flow constructed wetlands; as a result, their application in wastewater treatment has been increased and expanded worl...

The removal of toxic materials is becoming ever more critical due to diminishing water resources, increasing wastewater disposal costs, and stricter discharge regulations that have lowered permissible contaminant levels in waste streams. The present work presents an overview of various techniques (such as chemical precipitation, electrochemical tre...

Ozonation and sonication were applied to baker's yeast wastewater with high molasses content, under various operation conditions, in order to study the effect of them on COD (Chemical Oxygen Demand) removal and on methane enhancement. The ozonation treatment resulted in a significant reduction of the COD content; the COD removal was up to 38% after...

The aim of this work was the assessment of the environmental impact of different origin fly ashes with regard to their final disposal. The experimental procedure included the performance of single column tests and column tests of fly ash and soil in series. The appraisal of the potential environmental hazards was implemented using physicochemical a...

The possibility and efficiency of Lactobacillus kefiri and manganese peroxidase (MP) producing bacteria for the removal of melanoidins from synthetic and real melanoidins solutions were evaluated in this study. Samples collected from bench scale bioreactor treating melanoidins wastewater (90% v/v) were studied for screening and isolation of bacteri...

This study was conducted to evaluate the changes in microbiological, physical and chemical quality in wastewater during treatment operations of 17 wastewater treatment plants (WTPs) in cold and hot climate over a one-year period and to evaluate the quality of wastewater in drainages that discharges from these WTPs distributed in the province of Al-...

Non-Revenue Water (NRW) in urban water distribution networks is a very demanding task to handle. NRW impacts are economic (lost revenues), environmental (water and energy losses) and social (inefficient water pricing policies not based on the actual water consumption profile/patterns). To deal with NRW, water utilities turn to water audit tools and...

Climate change conditions and water demand growth are two main factors stressing water resources. The problem gets more severe in the countries facing water scarcity conditions, such as the Mediterranean basin countries. The Non-Revenue Water (NRW) problem is well acknowledged in areas facing severe water sacristy problems, but not all water utilit...

Background The aim of this work was the examination of molasses wastewater treatment by the combination of activated sludge with ozonation, for the effective removal of refractories. In addition to biological treatment, samples were subjected to: a) ozonation prior to activated sludge; b) ozonation coupled by addition of hydrogen peroxide prior to...

Limited amounts of industrial residues are recycled while the remaining huge quantities are stockpiled or disposed of, thus frequently leading to soil contamination. The utilization of industrial residues as valuable secondary resources into ceramics can contribute to efficient waste management and substitution for massive amounts of natural resour...

The current global trend towards increasingly stringent environmental standards and efforts for efficient utilization and re-use of available by-products and/or wastes, favors the use of low-cost sorbent materials for the treatment of heavy metal-contaminated solid wastes. In this study, the stabilization of tannery sludge, produced from the physic...

Membrane fouling is one of the most important considerations in the design and operation of membrane systems as it affects pretreatment needs, cleaning requirements, operating conditions, cost and performance. Given that membrane fouling represents the main limitation to membrane process operation, it is unsurprising that the majority of membrane m...

The objective of this work was the examination of the stabilization of sewage sludge by the addition of a steel slag (slag), and the investigation of the effect of stabilization time on the properties of the produced mixtures. The used slag was a by-product from steelmaking refining processes in ladle furnaces, the steelmaking slag that presented h...

The membrane biological reactor (MBR) configuration has proven to be optimal for treatment of many industrial wastewaters, especially when optimized treatment efficiencies are an important consideration. Ceramic MBR is being consolidated as a reliable technology for industrial applications, due to the benefits of the system, while ceramic membranes...