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

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 degrees 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.     

Alpha-thalassaemia prenatal diagnosis by two PCR-based methods

In Cyprus all couples carrying α⁰-thalassaemia mutations are detected in the course of the thalassaemia carrier screening program and prenatal diagnosis is offered to all of them. Prenatal diagnosis for α-thalassaemia is routinely done by two independent molecular methods. With the first method, the mutations of the parents are directly determined by gap-PCR and then the chorionic villus sample (CVS) is examined for the presence of these mutations. With the other method, a (CA)_n repeat polymorphic site located between the ψα₁- and α₂-globin genes is used for determining the presence or absence of the normal and mutant alleles. In the period from 1995 to 1999, molecular analysis of 46 couples in which haematological data were consistent with deletion of two α-globin genes in both partners indicated that only 13 of them were actually at risk for haemoglobin (Hb) Bart's hydrops fetalis and prenatal diagnosis was provided in 16 pregnancies. The molecular diagnosis was possible in all cases with the use of both gap-PCR and (CA)_n repeat polymorphisms analysis. No misdiagnosed cases for α-thalassaemia have been reported to date. Copyright © 2001 John Wiley & Sons, Ltd.     

Quality assessment of composts in the Greek market: the need for standards and quality assurance

An extensive data survey and study of the Greek market for composts or products marketed as such was carried out in order to acquire a comprehensive image of the local situation, in view of the proposed operation of large municipal solid waste (MSW) composting facilities and EU legislation changes. Physical and chemical parameters (moisture, organic matter, electrical conductivity, pH and heavy metals), stability indicators (self-heating potential, germination index) and biological indicators (microbial population, pathogen indicators and selected pathogens) were analyzed for the assessment of product quality. Results revealed wide variations even within the same group of products, which is particularly significant for parameters directly related to environmental protection and public health. The heavy metal content ranged from levels exceeding the fairly lenient Greek standards to below the stringent limits for A+ class compost in Austria. About 25% of the composts examined met the heavy metal limits for the EU eco-label award. Salmonella spp. was not detected in any of the composts but Staphylococcus aureus and Clostridium perfringens were found in 17 and 96% of the composts respectively. Pathogen indicator microorganisms were present at levels above suggested limits in all the composts. The high variability of such important parameters in composts available on the Greek market suggests an urgent need for establishing quality assurance procedures and mechanisms in the country. Moreover, the wide range of limit values within EU member states suggests the need for developing EU compost quality standards, in order to harmonize the compost markets.     

Fate and effect of linuron and metribuzin on the co-composting of green waste and sewage sludge

The fate and effect of the herbicides linuron and metribuzin on the co-composting of sewage sludge and green waste were addressed in this work. The experiments were conducted in metal cubic containers of 1.0 m³ volume simulating a windrow composting system. A mixture of sludge and green waste was prepared at a ratio of 1:5 v/v. The mixture was split in four equal parts and the two herbicides were added, using a pressure sprayer, as sole or mixed pollutant in each of the three mixtures. The forth mixture was composted without any addition of herbicide, to serve as control. Temperature, physicochemical characteristics, herbicide concentration, carbon dioxide emission, methane emission and microbiological parameters were measured either daily or every time the mixtures were turned, for a period of 80 days. Both herbicides’ concentration decreased significantly resulting in removal efficiencies of 99.1–99.7% and 95.8–96.0% for linuron and metribuzin, respectively. Incubation of microbiologically inactive mixtures at a temperature schedule following the spontaneous temperature evolution in the composters resulted in very little (1–11%) decomposition for both herbicides. Comparison of the variation of physicochemical parameters and microbial populations during composting indicated that both herbicides did not affect the composting process.     

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 O₂ and CO₂ 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.