Katia Lasaridi

Integrated aerobic biological treatment and chemical oxidation with Fenton’s reagent for the processing of green table olive wastewater

Table olive processing wastewater (TOPW) is unsuitable for disposal at municipal or industrial wastewater treatment plants due to its high organic and phenol content. Aerobic biological treatment using an Aspergillus niger strain in a bubble column bioreactor in combination with chemical oxidation was studied for the management of TOPW to a quality which corresponds to the input standards for wastewater treatment plants (COD < 1200 ppm, BOD < 500 ppm). After 2 days of biological treatment COD was reduced by 70%, while the total and simple phenolic compounds were decreased by 41 and 85%, respectively. In the chemical treatment step, the effect of different H 2 O 2 concentrations on the patterns of COD and phenol reduction was studied. The main effect of the chemical oxidation step was the elimination of persistent phenolic compounds during the biological treatment of total phenolic compounds. Coagulation with CaO significantly improved the efficiency of the process.

Measuring waste prevention

The Waste Framework Directive (WFD-2008/98/EC) has set clear waste prevention procedures, including reporting, reviewing, monitoring and evaluating. Based on the WFD, the European Commission and will offer support to Member States on how to develop waste prevention programmes through guidelines and information sharing on best practices. Monitoring and evaluating waste prevention activities are critical, as they constitute the main tools to enable policy makers, at the national and local level, to build their strategic plans and ensure that waste prevention initiatives are effective and deliver behaviour change. However, how one can measure something that is not there, remains an important and unresolved research question. The paper reviews and attempts to evaluate the methods that are being used for measuring waste prevention and the impact of relevant implemented activities at the household level, as the available data is still limited.

Microbial characterization during composting of biowaste

Windrow composting of source-separated biowaste was studied in a pilot plant in Crete, with regard to abiotic factors, gas concentration in the pile and succession of functional microbial groups. The pH, C/N ratio and VS content, as well as the O(2) and CO(2) concentration, correlated well with composting time, indicating typical composting behaviour. Most of the microbial groups examined exhibited their highest counts towards the end of the thermophilic phase, with declining trends thereafter. The population of total mesophilic and thermophilic bacteria increased during the mild thermophilic phase and followed the temperature decline thereafter. Results on these microbial groups and fungi indicate that the timing of the thermophilic stage in the composting process, in addition to the peak temperature and duration of the stage, affects the microbial succession. Escherichia coli were detected for over 2 months of processing, in spite of the high temperatures achieved; only after about 3 months of composting did its population decline below the detection limit.

Attitudes and behaviour of Greek households regarding food waste prevention.

Food waste is a waste stream with serious economic, environmental and social implications. The emphasis of the reported research is on the food waste generated by households in Greece. A structured questionnaire was utilised in order to identify the attitudes of the respondents and investigate the prevalence of certain behavioural good practices that can prevent the generation of food waste. The research, to our knowledge the first of its kind in Greece, took place in February and March 2012. Face-to-face interviews were employed, resulting to a total of 231 consumers fully completing the questionnaire. Results indicate that, based on self-reported behaviour, people in Greece have positive attitudes towards food waste prevention and that their habits are close to the good practices suggested in the literature for reducing food waste. For instance, most respondents do plan their food shopping in a multitude of ways and are very careful in their purchases of fresh food supplies. However, about 40% misunderstand the meaning of food date labels. The positive findings are strongly influenced by the severe recession experienced in the country, which makes consumers more conscious of their spending. Results may serve as a yardstick to further promote and establish food waste prevention behaviour at the household level on an environmental and social awareness basis that may outlast the economic crisis.

Household waste compositional analysis variation from insular communities in the framework of waste prevention strategy plans.

Waste management planning requires reliable data regarding waste generation, affecting factors on waste generation and forecasts of waste quantities based on facts. In order to decrease the environmental impacts of waste management the choice of prevention plan as well as the treatment method must be based on the features of the waste that are produced in a specific area. Factors such as culture, economic development, climate, and energy sources have an impact on waste composition; composition influences the need of collecting waste more or less frequently of waste collection and disposition. The research question was to discover the main barriers concerning the compositional analysis in Insular Communities under warm climate conditions and the findings from this study enabled the main contents of a waste management plan to be established. These included advice to residents on waste minimisation, liaison with stakeholders and the expansion of kerbside recycling schemes.

Pilot-scale anaerobic co-digestion of sewage sludge with agro-industrial by-products for increased biogas production of existing digesters at wastewater treatment plants

Due to low degradability of dry solids, most of the digesters at wastewater treatment plants (WWTP) operate at low loading rates resulting in poor biogas yields. In this study, co-digestion of sewage sludge (SS) with olive mill wastewater (OMW), cheese whey (CW) and crude glycerol (CG) was studied in an attempt to improve biogas production of existing digesters at WWTPs. The effect of agro-industrial by-products in biogas production was investigated using a 220L pilot-scale (180L working volume) digester under mesophilic conditions (35°C) with a total feeding volume of 7.5L daily and a 24-day hydraulic retention time. The initial feed was sewage sludge and the bioreactor was operated using this feed for 40days. Each agro-industrial by-product was then added to the feed so that the reactor was fed continuously with 95% sewage sludge and 5% (v/v) of each examined agro-industrial by-product. The experiments showed that a 5% (v/v) addition of OMW, CG or CW to sewage sludge significantly increased biogas production by nearly 220%, 350% and 86% as values of 34.8±3.2L/d, 185.7±15.3L/d and 45.9±3.6L/d respectively, compared to that with sewage sludge alone (375ml daily, 5% v/v in the feed). The average removal of dissolved chemical oxygen demand (d-COD) ranged between 72 and 99% for organic loading rates between 0.9 and 1.5kgVSm-3d-1. Reduction in the volatile solids ranged between 25 and 40%. This work suggests that methane can be produced very efficiently by adding a small concentration (5%) of agro-industrial by-products and especially CG in the inlet of digesters treating sewage sludge.

Assessing odour nuisance from wastewater treatment and composting facilities in Greece

The problem of odour nuisances in Greece was explored using: (a) field measurements of a range of malodorous compounds (hydrogen sulfide, ammonia, benzene, toluene, xylenes, formaldehyde, acetaldehyde, acetone, methyl-mercaptan and carbonyl sulfide) from selected wastewater treatment plants and composting facilities; and (b) questionnaires, completed by wastewater treatment plant operators, to investigate potential odour problems, the odour abatement technologies used, and potential interest and motives for adopting such technologies. The sparse information available in the literature is also exploited. Results indicate that on several occasions there was an odour problem, often stemming from the uncontrolled city sprawl, which results in mixed and often conflicting land uses. This is particularly true for wastewater treatment plants, which tend to be built close to built-up areas and highlights the importance of town planning as a tool to minimize odour problems. Measurement of odours and/or odour related gases is not commonly practised in Greece, while the odour abatement systems currently used are often considered inadequate by plant managers who do have an active interest in using more efficient and effective technologies. To our knowledge, this is the first systematic effort to monitor the odour nuisance in the country.

Benefits from GIS Based Modelling for Municipal Solid Waste Management

Waste management issues are coming to the forefront of the global environmental agenda at an increasing frequency, as population and consumption growth result in increasing quantities of waste. Moreover, technological development often results in consumer products of complex composition, including hazardous compounds, which pose extra challenges to the waste management systems and environmental protection at the end of their useful life, which may often be fairly short (e.g. cell-phones and electronic gadgets). These end-of-pipe challenges are coupled with the deepening understanding that the Earth’s natural resources are finite by nature and their current exploitation rate unsustainable, even within a midterm perspective. The self-cleaning capacity of the Earth systems is often also viewed as a «natural resource» under stress, with climate change being the most pronounced expression of this risk. In the context of the above mentioned challenge a New Paradigm for waste management has emerged, shifting attention to resources efficiency and minimisation of environmental impacts throughout the life cycle of waste management, from waste prevention to safe disposal. This is best expressed, but not confined, in the relevant EU policy and legislation (e.g. the Thematic Strategy on the prevention and recycling of waste, the Thematic Strategy on the Sustainable Use of Natural Resources and the revised Waste Framework Directive, WFD-2008/98/EC). Especially the latter is of particular interest as it has a legally binding nature for all EU member states and sets a benchmark which is often also taken into consideration by the waste management systems of non-EU countries. The WFD reaffirms the need to move waste management higher in the so called “waste hierarchy”, preferring, in this order, prevention, reuse, recycling and energy recovery over disposal. Separate collection for dry recyclables in municipal solid waste (MSW) should be implemented while separate collection of biowaste should be promoted (although no specific legislative requirements are set) (Nash, 2009). Overall, EU and national waste management policies and legislation in many parts of the world are becoming increasingly demanding for the providers of these services, namely municipalities and their associations, demanding high recovery and recycling rates for a wide range of materials and goods, high diversion targets for the biodegradable fraction of the waste, advanced treatment processes, long after-care periods for existing and future landfills etc (COM, 2005; Lasaridi, 2009). Moreover, this increased level of service will need to be provided at the minimum possible cost, as the public will not be able to bear large

Integrated waste management through producers and consumers education: Composting of vegetable crop residues for reuse in cultivation

Abstract As part of the design of an integrated waste management scheme through the use of the PRECEDE/PROCEED model in the area of Crete, data concerning the applicability of composting in various agricultural wastes was considered as necessary. Vegetable residues from tomato, cucumber, eggplant, and pepper crops were collected, shredded and composted either alone or with the use of olive press cake, olive tree leaves, and branches and vine branches as bulking agents. Seven random combinations—mixtures of the above materials were composted using windrows, where additional four similar windrows were made up by approximately 10 m3 of the above mentioned vegetable crop residues. All windrows were turned four times during the eight weeks thermophylic phase, with the help of a mechanical turner. A large number of physiochemical parameters were monitored in the raw materials, at the end of the thermophylic phase and at the end of the maturation phase. The temperature which was monitored daily, recorded the highest values (above 55°C) in the windrows where bulking agents were used. All raw vegetable crop residues and their mixtures presented increased electrical conductivity values (above 5 mS/cm and up to 9.7 mS/cm) resulting to end products with respectively high EC values (above 3 mS/cm and up to 15 mS/cm) probably due to the presence of large amounts of soil, rich in fertilisers, attached to the roots of the plants. There was no detection of any remains of the 13 pesticides for which all 11 composts were tested for. The accuracy of the results was tested through a recovery test of the pesticides in mature compost, resulting to acceptable recovery values.

Food waste prevention in Athens, Greece: The effect of family characteristics

Food waste is a stream that becomes increasingly important in terms of its prevention potential. There is a large number of behaviours that can be associated with food waste generation and the efforts towards food waste prevention. A questionnaire study was carried in order to study consumer behaviour related to food provision and wastage in Greece. Proper practices of the respondents that can prevent the generation of food waste were investigated using nine behavioural scales, which were defined on the basis of similar studies in other countries. A structured questionnaire was utilised in order to test those behaviours against the socio-demographic characteristics of respondents. The results of the study indicate that in terms of inferential statistical analysis, among the numerous variables examined, those that enhance food waste prevention are the involvement of the respondent in cooking, the annoyance towards food waste generation and the education level.