The food for feed concept. Performance of broilers fed hotel food residues.

1. In recent times the use of food waste in animal diets has gained considerable attention because of the increasing demand to cover the needs of human population and the high prices of conventional, arable based, animal feeds.2. The aim of the present study was to investigate the effect of adding dried human food waste to the diet of meat-type chickens (broilers). Two hundred, one-day-old broilers were divided into two treatment groups, with 10 replicate pens containing 10 birds per pen. The duration of the study was 42 days. In the control (C), the diet did not contain any food waste, whereas in the second treatment (T) food waste residues from hotels made up 15% of the diet. Diets had similar crude protein and metabolisable energy content.3. Feed intake and body weight were recorded in order to calculate weight gain and feed conversion ratio (FCR). Carcase and breast muscle yield, the weight of selected internal organs and the level of selected biochemical and haematological parameters were determined. Quality of breast muscle meat was assessed.4. Broilers fed the control treatment consumed more feed and gained more weight compared to broilers fed waste; however, the FCR was similar. No major differences were seen for internal organ weights and haematological parameters, although some differences were observed in colour traits and shear force of meat. It was concluded that there is a potential for use of food waste in broiler diets.

Occurrence of pharmaceuticals in the wastewater of a Greek hospital: Combining consumption data collection and LC-QTOF-MS analysis.

In this article we applied drug consumption approach and chemical analysis in parallel to investigate the concentrations of a large number of pharmaceuticals in different streams of a General Hospital. Drugs consumption data was collected during two periods (Period 1, 2) and the predicted environmental concentrations (PECs) were estimated for the wastewater of a building housing specific medical services (Point A) and for the entire hospital (Point B). Hospital wastewater samples (HWW) samples were also collected from these points and periods and the measured environmental concentrations (MEC) were determined using UHPLC-ESI-QTOF-MS/MS. According to consumption data, the highest number of drugs was consumed in the departments of Hematology, Intensive Care Unit, Cardiology, Internal Medicine, and Oncology, while the number of active substances used in the hospital was 413 (Period 1) and 362 (Period 2). For most substances, much higher PEC and MEC values were found at the HWW of Point A indicating that on-site treatment of this stream could be examined in the future. The application of wide-scope target analysis allowed the quantification of 122 compounds, while 21 additional substances were identified using suspect screening. The highest mean concentrations in Period 1 were found for acetaminophen (1100 µg/L) and rifaximin (723 µg/L), while in Period 2 for iopromide (458 µg/L) and acyclovir (408 µg/L). Among the detected compounds, 19 metabolites were determined. Atenolol acid, 1-hydroxy-midazolam and clopidogrel carboxylic acid were quantified at concentrations much higher than parent compounds indicating the importance of metabolites' monitoring in HWW. Calculation of PEC/MEC ratio for 36 pharmaceuticals showed sufficient correlation of these values for 19 % to 33 % of the substances depending on the examined period and sampling point. The parallel collection of drugs consumption data and chemical analysis give a thorough picture of the substances present in HWW and their main sources, facilitating decision-making for their better management.

Pilot-scale comparison of constructed wetlands operated under high hydraulic loading rates and attached biofilm reactors for domestic wastewater treatment.

Four different pilot-scale treatment units were constructed to compare the feasibility of treating domestic wastewater in the City of Heraklio, Crete, Greece: (a) a free water surface (FWS) wetland system, (b) a horizontal subsurface flow (HSF) wetland system, (c) a rotating biological contactor (RBC), and (d) a packed bed filter (PBF). All units operated in parallel at various hydraulic loading rates (HLR) ranging from 50% to 175% of designed operating HLR. The study was conducted during an 8 month period and showed that COD removal efficiency of HSF was comparable (>75%) to that of RBC and PBF, whereas that of the FWS system was only 57%. Average nutrient removal efficiencies for FWS, HSF, RBC and PBF were 6%, 21%, 40% and 43%, respectively for total nitrogen and 21%, 39%, 41% and 42%, respectively for total phosphorus. Removals of total coliforms were lowest in FWS and PBF (1.3 log units) and higher in HSF and RBC (2.3 to 2.6 log units). HSF showed slightly lower but comparable effluent quality to that of RBC and PBF systems, but the construction cost and energy requirements for this system are significantly lower. Overall the final decision for the best non-conventional wastewater treatment system depends on the construction and operation cost, the area demand and the required quality of effluent.

Oil refinery sludge and green waste simulated windrow composting.

Oil refinery sludge (ORS) was mixed with shredded green wastes (GW) at ratios of 1:1 v/v (RI) and 1:3 v/v (RII). The mixtures, of approximately volumes of 1,020 l and 990 l respectively, were introduced in metal cubic containers of 1.0 m(3) volume, opened at the top and with small holes punctured in the bottom and the side. The containers were additionally insulated with a layer of rockwool (20 mm). The boxes were emptied, the mixtures were turned and water was added occasionally, in one to two weeks intervals, simulating a windrow composting system. Temperature, physiochemical characteristics, mineral oil and grease (MOG) concentration, polycyclic aromatic hydrocarbons (PAHs) concentration, carbon dioxide emission, methane emission and microorganisms presence were recorded either daily or every time the mixtures were turned, for a period of 120 days. RII recorded temperatures as high as 62 degrees C, reaching 56 degrees C in Day 6 and retained temperatures above 50 degrees C for more than 40 days. RI recorded its highest temperature of 53 degrees C in Day 77. The reason why the two mixtures behaved so differently can be explained by: (i) extended co-digestion phenomena by the microorganisms decomposing the GW in RII, (ii) toxic effect of ORS in RI due to the far larger amounts used (840 kg in RI in comparison with the 460 kg in RII). After Day 36 temperature increased gradually in RI and MOG and PAHs reduction was first noted. At the end of the experiment MOG concentration in RI was 57.2 mg/kg dry weight (dw) (52.1% reduction) where in RII was 34.3 mg/kg dw (62.1% reduction). Emissions of methane and carbon dioxide support the concept of the toxic effect and the delay ignition of the decomposing process in RI. In total, CO(2) and CH(4) emissions from RI were recorded to be 30.8 kg and 18.5 g, respectively, where from RII 59.6 kg of CO(2) and 6.4 g of CH(4) were emitted. An effort was made to determine the effect of temperature alone (as an abiotic treating parameter) in both mixtures. It can be supported that about least 15% of the MOG and PAHs removal.

Screening for faecal contamination in primary schools in Crete, Greece.

BACKGROUND: Hygienic conditions in primary schools are a major concern for both governmental organizations and families. Particularly, the occurrence of faecal indicators on children's hands and various school surfaces has been associated with increased risk of diarrhoeal diseases. The presence of faecal streptococci on environmental surfaces and children's hands and the possible correlation with socio-economic factors were examined. METHODS: Overall, 1956 samples from hands and 1470 samples from surfaces were collected from 20 primary schools in Heraklion, Crete, Greece. RESULTS: Faecal streptococci were found at 52.9% of children's hands and at 16.7% of other surfaces. Children, who had parents with the highest education level (>12 years), had the lowest percentage (48.8%) of faecal contamination on their hands. Furthermore, boys exhibited higher levels of hands contamination compared with girls. Among the environmental surfaces examined, the school canteen reception was the most contaminated area. CONCLUSION: High faecal contamination was detected in primary schools in the examined region. Children's hands were highly infected (52.9%), while boys exhibited higher levels of contamination. The educational level of parents correlated well with the contamination of children's hands.

The role of bulking agent in pile methane and carbon dioxide concentration during wastewater sludge windrow composting.

Wastewater sludge and wood chips were used as feedstock for the construction of two piles, Pile I ("PI") and Pile II ("PII"), at a ratio of 1:1 and 1:2 v/v, respectively. Each pile was originally 1.3-m high, 2.0-m wide, and approximately 9.0-m long. A mechanical turner was used to turn the two windrows every 1 to 2 weeks. Three 500-mL-volume glass funnels were inverted and introduced into each pile: one in the core (named, respectively, "PIC" and "PIIC"), one at the top ("PIT" and "PIIT"), and one at the side ("PIS" and "PIIS"). Every 2 to 3 days, gas samples were collected using gas-tight syringes and analyzed in a gas chromatograph determining carbon dioxide (CO2) and methane (CH4) concentrations. An average gas concentration value between turnings was calculated and a two-way analysis of variance test was used to determine the significance of the differences between piles and pile location, followed by a Post Hoc Tukey test. During the thermophilic period, the mean CO2 concentration in PIC was 103 mL/L, 65 mL/L in PIT, and 24 mL/L in PIS, whereas, for PII, these values were 102mL/L, 59 mL/L, and 24 mL/L, respectively. The mean CH4 concentration between turnings in PIC was 9.2 mL/L, 1.9 mL/L in PIT, and 0.9 mL/L in PIS, whereas, for PII, the corresponding values were 6.4 mL/L, 0.4 mL/L, and 0.1 mL/L. For methane, there were no significant differences between these mean values, not only between the same placement in different piles, but also between different placements and different piles. This is probably due to the relatively frequent turnings (10 turnings during a period of 100 days), which did not allow the development of more anaerobic pockets in PI than in PII, indicating that both piles had similar greenhouse gas impacts. Results for carbon dioxide were similar in both piles, with some differentiation appearing between the core and top placements compared to the side placement. Reduction of the decomposition rate further from the core and a typical windrow chimney effect (gases from the core flowing through the top) explain this similarity between placements. The similarity between piles can be explained by the similar amounts of easily decomposable organic matter found in both piles, indicating that the effect of the bulking agent ratio on the concentration of gases within the pile was not significant.

Effects of treated wastewater irrigation on the establishment of young grapevines.

Irrigation with treated wastewater could produce excessive accumulations within the plant and soil, negatively affecting the yield and production quality. In addition, the presence of biological and chemical contaminants could harm the agricultural environment, as well as the health of farmers and consumers. During this work, the suitability of secondary and tertiary treated wastewater for use in young grapevines was evaluated by studying the effect of the wastewater irrigation on the soil-plant system, crop yield, fruit quality and the presence of inorganic chemical contamination (salts, elements and heavy metals), organic chemical contamination (polycyclic aromatic hydrocarbons) and microbial contamination (E. coli, total coliforms). The results show that tertiary treated wastewater had positive impact on plant growth and yield while secondary treated wastewater had negative impact on fruit safety in comparison with tap water. Sodium levels in soils irrigated with treated wastewater increased at the end of the irrigation period while decreased during the wet season. The total polycyclic aromatic hydrocarbon concentrations in the soils ranged from 363 µg/kg to 374 µg/kg at the end of the experiment for all irrigation treatments applied. The use of tertiary treated wastewater was recommended for the irrigation of young grapevines as an alternative water source secured protection of environment, plant health and fruit quality.

Evaluating the use of electrical resistivity imaging technique for improving CH(4) and CO(2) emission rate estimations in landfills.

In order to improve the estimation of surface gas emissions in landfill, we evaluated a combination of geophysical and greenhouse gas measurement methodologies. Based on fifteen 2D electrical resistivity tomographies (ERTs), longitudinal cross section images of the buried waste layers were developed, identifying place and cross section size of organic waste (OW), organic waste saturated in leachates (SOW), low organic and non-organic waste. CH(4) and CO(2) emission measurements were then conducted using the static chamber technique at 5 surface points along two tomographies: (a) across a high-emitting area, ERT#2, where different amounts of relatively fresh OW and SOW were detected, and (b) across the oldest (at least eight years) cell in the landfill, ERT#6, with significant amounts of OW. Where the highest emission rates were recorded, they were strongly affected by the thickness of the OW and SOW fraction underneath each gas sampling point. The main reason for lower than expected values was the age of the layered buried waste. Lower than predicted emissions were also attributed to soil condition, which was the case at sampling points with surface ponding, i.e. surface accumulation of leachate (or precipitated water).

Constructed wetlands treating highway runoff in the central Mediterranean region.

Two free water surface (FWS) and two subsurface flow (SSF) pilot-size constructed wetlands treating highway runoff (HRO) were monitored over a period of two years (September 2005-August 2007). One FWS and one SSF were designed with a hydraulic retention time (HRT) of 12h, named FWS12 and SSF12, respectively, with each one capable of treating a maximum HRO of 12.6 m(3) d(-1). The other couple, named FWS24 and SSF24, respectively, was designed with an HRT of 24h, with each receiving a maximum HRO of 6.3 m(3) d(-1). The influent flowed from a highway section with a total surface 2752 m(2) on the island of Crete, Greece, in the heart of the South-Central Mediterranean region. Influent and effluent were monitored for COD, TSS, total N (TN), NO(3)(-) and total P (TP) concentrations. Furthermore, removal efficiencies were examined for heavy metals (Cu, Ni, Pb, Zn) for both years, while polycyclic aromatic compounds (PAHs) were examined for the period between September 2006 and August 2007. The influent had a two-year average COD value of 101 mg l(-1), whereas the mean values for TSS, TN, N-NO(3)(-) and TP were 203, 4.30, 1.25 and 4.17 mg l(-1), respectively. For Cu, Ni, Pb and Zn the respective two-year mean influent concentrations were 56, 114, 49 and 250 microg l(-1). Mean concentration of total PAHs in runoff (summation operator PAHs, 16 compounds) were 12.01 microg l(-1). The performance among the four beds was not significantly different according to ANOVA analysis followed by Tukey test (at p<0.05) for almost all the above physicochemical parameters, suggesting that all systems performed in a similar way. All studied systems, achieved a mean of two-year removal efficiencies of 47% for COD, 89% for TSS, 49% for TN, 58% for N-NO(3)(-), 60% for TP, 47% for Cu, 23% for Ni, 33% for Pb, 61% for Zn and 59% for summation operator PAHs (16 compounds).

Boosting biogas production from sewage sludge by adding small amount of agro-industrial by-products and food waste residues.

In Greece, in many cities, wastewater treatment plants (WWTPs) operate their own anaerobic digestion (AD) facility in order to treat sewage sludge rather than achieve optimum biogas production. Nowadays, there is a growing interest regarding the addition of other co-substrates in these existing facilities in order to increase gas yield from the biomass. This practice may be possible by adding small amount of co-substrates which will not affect significantly in the designed hydraulic retention time. Nonetheless, the lack of experimental data regarding this option is a serious obstacle. In this study, the effect of co-digestion sewage sludge, with small amount of agro-industrial by-products and food wastes is examined in lab-scale experiments. Specifically, co-digestion of SS and food waste (FW), grape residues (GR), crude glycerol (CG), cheese whey (CW) and sheep manure (SM), in a small ratio of 5-10% (v/v) was investigated. The effect of agro-industrial by-products and food waste residues on biogas production was investigated using one 1L and three 3L lab-scale reactors under mesophilic conditions at a 24-day hydraulic retention time. The biogas production rate reached 223, 259, 406, 572, 682 and 1751 mlbiogas/lreactor/d for 100% SS, 5% SM & 95% SS, 10% CW & 90% SS, 5% FW & 95% SS, 5% FW & 5% CG & 90% SS and 5% CG & 95% SS respectively. Depending on the co-digestion material, the average removal of total chemical oxygen demand (TCOD) ranged between 20% (5% SM & 95% SS) and 76% (5% FW & 5% CG & 90% SS). Reduction in the volatile solids ranged between 26% (5% SM & 95% SS) and 62% (5% FW & 5% CG & 90% SS) for organic loading rates between 0.8kgVSm-3d-1 and 2.0kgVSm-3d-1. Moreover, co-digestion improved biogas production from 14% (5% SM & 95% SS) to 674% (5% CG & 95% SS). This work suggests that WWTPs in Greece can increase biogas production by adding other wastes to the sewage sludge without affecting the operation of existing digesters and without requiring additional facilities.

Improving biogas production from anaerobic co-digestion of sewage sludge with a thermal dried mixture of food waste, cheese whey and olive mill wastewater.

Anaerobic co-digestion of sewage sludge and other organic wastes at a wastewater treatment plant (WWTP) is a promising method for both energy and material recovery. However, transportation and storage of wastes to WWTP may be the bottleneck for the successful implementation of this technology. In case of wet wastes and wastewater it is possible to reduce their volume and as a result the transportation and storage cost by using a drying process. During this study, the optimization of biogas production from sewage sludge (SS) was attempted by co-digesting with a dried mixture of food waste, cheese whey and olive mill wastewater (FCO). A series of laboratory experiments were performed in continuously-operating reactors at 37°C, fed with thermal dried mixtures of FCO at concentrations of 3%, 5% and 7%. The overall process was designed with a hydraulic retention time (HRT) of 24days. FCO addition can boost biogas yields if the mixture exceeds 3% (v/v) concentration in the feed. Any further increase of 5% FCO causes a small increase in biogas production. The reactor treating the sewage sludge produced 287ml CH4/Lreactor/d before the addition of FCO and 815ml CH4/Lreactor/d (5% v/v in the feed). The extra FCO-COD added (7% FCO v/v) to the feed did not have a negative effect on reactor performance, but seemed to have the same results. In all cases, the estimated biodegradability of mixtures was over 80%, while the VS removal was 22% for the maximum biomethane production (5% v/v). Moreover, co-digestion improved biogas production by 1.2-2.7 times.

Production of organic fertilizer from olive mill wastewater by combining solar greenhouse drying and composting.

Olive mill wastewater (OMW) is generated during the production of olive oil. Its disposal is still a major environmental problem in Mediterranean countries, despite the fact that a large number of technologies have been proposed up to date. The present work examines for the first time a novel, simple and low-cost technology for OMW treatment combining solar drying and composting. In the first step, OMW was dried in a chamber inside a solar greenhouse using swine manure as a bulking agent. The mean evaporation rate was found to be 5.2 kg H2O/m2/d for a drying period of 6 months (February-August). High phenol (75%) and low nitrogen (15%) and carbon (15%) losses were recorded at the end of the solar drying process. The final product after solar drying was rich in nutrients (N: 27.8 g/kg, P: 7.3 g/kg, K: 81.6 g/kg) but still contained significant quantities of phenols (18.4 g/kg). In order to detoxify the final product, a composting process was applied as a second step with or without the use of grape marc as bulking agent. Results showed that the use of grape marc as a bulking agent at a volume ratio of 1:1 achieved a higher compost temperature profile (60 °C) than 2:1 (solar drying product: grape marc) or no use (solar drying product). The end product after the combination of solar drying and composting had the characteristics of an organic fertilizer (57% organic carbon) rich in nutrients (3.5% N, 1% P, 6.5% K) with quite low phenol content (2.9 g/kg). Finally, the use of this product for the cultivation of pepper plants approved its fertility which was found similar with commercial NPK fertilizers.

Halophytes as vertical-flow constructed wetland vegetation for domestic wastewater treatment.

Recent findings show that halophytes have the ability to accumulate salts in their tissues, making them a very interesting group of plants for domestic wastewater treatment in constructed wetlands (CWs). In that case, it might be possible to reduce the salinity of the final effluent, which is a crucial parameter for wastewater reuse in agriculture. During this study three halophytes, Atriplex halimus, Juncus acutus and Sarcocornia perennis, were tested for phyto-desalination of domestic wastewater in a vertical flow constructed wetland (VFCW) and compared with common reeds (Phragmites australis). In addition, the effect of this alternative vegetation on the overall performance of the system regarding organic matter, nutrients, boron and pathogen removal was monitored. The organic loading rate (OLR) was about 21gCOD/m2/d and the hydraulic loading rate (HLR) was 95mm/d in both cases. Promising results were obtained for A. halimus, which shows high biomass productivity and significant capability to accumulate salts, mainly Na, in its tissues. A positive effect on pathogen removal efficiency was also recorded. However, nitrogen concentration in the effluent of the VFCW planted with halophytes was found to be higher than in the effluent of the VFCW planted with reeds. Finally, no significant effect on organic matter and phosphorus removal efficiency was observed from the use of halophytes in place of reeds.

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.

Survival of total coliforms in lawn irrigated with secondary wastewater and chlorinated effluent in the Mediterranean region.

Pregrown, two-month-old lawn was layered in 12 large square pots with an area of 0.25 m2 each, filled with a mixture of topsoil, peat, and sand. In late July, in the heart of the Mediterranean summer, the pots were divided into two groups, with six pots per group. On four different occasions, the pots in each group were sprinkled (surface irrigation) with 2 L of either secondary-treated wastewater (STW, group A) or chlorinated effluent (CHE, group B). Wastewater application always took place at 0700 hours. Samples of the surface soil and grass from each pot were collected at the following times: before irrigation, immediately after irrigation, two hours later (0900 hours), and four hours later (1100 hours). In the samples collected, the number of total coliforms per gram was measured using standard microbiological analyses. Temperature and sunlight intensity were also monitored. There was an increase in the coliforms population in soil and grass samples of both groups immediately after the wastewater application. In group A, the mean number of coliforms recorded in the soil samples reached mean values higher than 5000 cfu/g compared to 312 cfu/g recorded before application. The increase in group B was smaller but still significant. Two hours later, the number of coliforms was reduced substantially in all samples (e.g., group A, soil samples 477 cfu/g). Coliform inactivation is thought to result from the effect of temperature and mainly sunlight. However, four hours after application (1100 hours), there was a noticeable increase in the coliform number again, in all sample categories of both groups. Coliform reactivation could be a result of shadowing effect resulting from the thick foliage of the grass, where the microorganisms were protected by the sunlight radiation and regrowth in a friendly environment (especially of the soil) where moisture and nutrients were present. This, in addition to the fact that coliforms seemed to retain a sizable population between applications, results in three conclusions: (1) coliforms can survive in grass and soil for a substantial period of time, recovering from the destructive effect of chlorination, (2) use of STW, even during the Mediterranean summer, could result in a substantial "contamination" of lawns, without any proof that sun and temperature can reduce the coliform number, and (3) intense sunlight (up to 68 000 lux) was far more effective in coliform suppression than elevated temperature (up to 38 degrees C).

Evaluation of primary and secondary treated and disinfected wastewater irrigation of tomato and cucumber plants under greenhouse conditions, regarding growth and safety considerations.

Tomato and cucumber seedlings were distributed into 10 groups (five for each plant) of 15 plants each. The plants were irrigated for 10 weeks with primary treated wastewater (group A), secondary treated wastewater (group B), chlorinated secondary treated wastewater (group C), a fertilizer dilution (group F), and tap water (group M). All precautions were taken to secure that there was no direct contact between the wastewater and the edible portions of the crops. During this period and on a weekly basis, the height and number of leaves was monitored, while, at the end, the dry weight of leaves, stems, and roots for each plant of each group was measured. Based on these growth parameters, both types of plant in groups A and F recorded the most significant development compared to the other three groups. The plants irrigated with tap water recorded the smallest development, in every case. Plants in groups B and C were similar, with a slight (but not significant) superiority for the plants irrigated with secondary treated wastewater, probably as a result of some phytotoxic effects of residual chloride in the chlorinated wastewater. The presence of nutrients and specifically nitrogen in the various solutions explains the differences satisfactorily. The vegetables grown on the plants of each group were harvested, and their surface tissue analyzed for total coliforms (TC) and enterococci (EC). Tomatoes grown on the plants of groups A and B recorded the highest values for TC, with 505 and 490 cfu/g, respectively, whereas, for cucumbers, those values were 342 and 450 cfu/g, respectively. Enterococci were detected on the surface of harvested vegetables from groups A and B, but the small number of cases and their random character cannot support any strong relations between the used wastewater and their presence. The TC values in group C were very low, far lower than those if group F. No EC were found in either group C or group F. These primary results suggested that irrigation with appropriate disinfected wastewater, even of such high-risk cultivations of vegetables eaten raw, should not be discarded completely as unsafe, but be reconsidered and studied further. However, the use of undisinfected wastewater in such greenhouse cultivations, where all safety precautions have been taken to prevent any contact of the fruits with the soil or the wastewater, does not prove to be 100% safe.

Single house on-site grey water treatment using a submerged membrane bioreactor for toilet flushing.

Wastewater recycling has been and continues to be practiced all over the world for a variety of reasons including: increasing water availability, combating water shortages and drought, and supporting environmental and public health protection. Nowadays, one of the most interesting issues for wastewater recycling is the on-site treatment and reuse of grey water. During this study the efficiency of a compact Submerged Membrane Bioreactor (SMBR) system to treat real grey water in a single house in Crete, Greece, was examined. In the study, grey water was collected from a bathtub, shower and washing machine containing significant amounts of organic matter and pathogens. Chemical oxygen demand (COD) removal in the system was approximately 87%. Total suspended solids (TSS) were reduced from 95mgL(-1) in the influent to 8mgL(-1) in the effluent. The efficiency of the system to reduce anionic surfactants was about 80%. Fecal and total coliforms decreased significantly using the SMBR system due to rejection, by the membrane, used in the study. Overall, the SMBR treatment produces average effluent values that would satisfy international guidelines for indoor reuse applications such as toilet flushing.

The composting potential of different organic solid wastes: experience from the island of Crete.

For the past 20 years, the National Foundation for Agricultural Research in Crete and the School of Agricultural Technology of the Technological and Educational Institute of Crete have been involved in a number of research and development activities, related to the production and evaluation of compost derived from a variety of local solid, mainly agricultural organic wastes. Materials such as olive press cake, olive tree leaves (OTL) and branches, vine branches (VB), pressed grape skins (PGS), pig manure (PM), sewage sludge and the organic fraction of municipal solid waste (OFMSW) have been evaluated for their behaviour during composting, their compatibility in mixtures and the quality of the end product. The quality evaluation included both a detailed physiochemical (pH, electrical conductivity (EC), nutrients concentration, heavy metal concentration, etc.) and biological analyses (pathogenic microorganisms). It also included an agronomic evaluation, in which composts were used either as a soil amendment or as a component for substrates in open air or covered (greenhouse) cultivation mainly of local vegetables (tomatoes, cucumbers, etc.). All materials were composted successfully, especially when mixed. The end products contained large amounts of organic matter, usually combined with an increased EC value. Pressed grape skins should be considered as the ideal raw material, producing a high quality compost, with the lowest EC value (1.57 mS cm(-1)) and the largest organic matter concentration (84.50%), compared to all other materials. When any of the produced compost was used in a ratio of 30% by volume (v/v), it increased plant growth, whereas in larger volumes, it presented phytotoxic behaviour, inhibiting both root and shoot development.

Removal of heavy metals from a metaliferous water solution by Typha latifolia plants and sewage sludge compost.

Typha latifolia plants, commonly known as cattails, were grown in a mixture of mature sewage sludge compost, commercial compost and perlite (2:1:1 by volume). Four Groups (A, B, C and D) were irrigated (once every two weeks) with a solution containing different concentrations of Cu, Ni, and Zn, where in the fifth (group M) tap water was used. At the end of the 10 weeks experimental period substrate and plants were dried, weighed and analysed for heavy metals. The amounts of all three metals removed from the irrigation solution, were substantial. In the roots and leaves/stems of T. latifolia the mean concentration of Zn reached values of 391.7 and 60.8 mg/kg of dry weight (d.w.), respectively. In the substrate of Group D all three metals recorded their highest mean concentrations of 1156.7 mg/kg d.w. for Cu, 296.7 mg/kg d.w. for Ni and 1231.7 mg/kg d.w. for Zn. Linear correlation analyses suggested that there was a linear relationship between the concentration of metals in the solutions and the concentration of metals in the substrates at the end of the experiment. The percentage removal of the metals in the substrate was large, reaching 100% for Cu and Zn in some groups and almost 96% for Ni in group D. The total amount of metals removed by the plants was considerably smaller than that of the substrate, due mainly to the small biomass development. A single factor ANOVA test (5% level) indicated that the build up in the concentration of metals in the roots and the leaves/stems was due to the use of metaliferous water solution and not from the metals pre-existing in the substrate. The contribution of the plants (both roots and leaves/stems) in the removing ability of the system was less than 1%.

The removal of chemical oxygen demand from primary-treated domestic wastewater in subsurface-flow reed beds using different substrates.

Subsurface-flow experimental reed beds were designed and built based on a combination of two design methodologies. Four different growing media were used with a combination of topsoil, gravel, river sand, and mature wastewater biosolids compost to determine the best substrate for chemical oxygen demand removal. Eight units were constructed, two for each material. One bed for each pair was planted with Typha latifolia plants commonly known as cattails. Primary-treated domestic wastewater was continuously fed to the beds for more than 6 months. The best performance was achieved by the gravel reed beds, with an average removal rate higher than 50%. Soil-based beds containing topsoil and sand only managed to attain removals of approximately 10%. The reed beds containing compost in their substrate produced the worst treatment, mainly because of leaching of organic substances from the compost. Primarily as a result of channel flow, all beds showed significant deviation from the designed retention time. There was no significant difference in the performance of planted and unplanted reed beds.