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Digested sludge samples from domestic wastewater treatment plants located in Northern Italy were tested as far as the presence of viruses (enteric viruses and coliphages), bacteria (faecal coliforms, salmonella) and helminth eggs is concerned. Heavy metals were also analysed. Escherichia coli bacteriophages and faecal coliforms were isolated from all samples, while salmonellae and helminth eggs were isolated only from four and three out of 27 total samples, respectively. The 66% of sludge samples, 46 and 82% of aerobic and anaerobic digested sludges respectively, showed the presence of enteric viruses (enteroviruses and reoviruses). The virus concentrations ranged from 0.6 to 123 MPNCU/g. Results of this study suggest that significant concentrations of pathogens such as enteric viruses can be present in digested sludge, which showed compliance with Italian legislation. As suggested by other authors, there is the need for surveillance and reference indications both in EU (European Union) and Italian regulations concerning the use of sludge in agriculture. [ABSTRACT FROM AUTHOR]

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Low-temperature environment leads to a weakened ability of sludge bio-drying to drive system evaporation and the system's water removal capacity of aeration (ΣF·ΔP), significantly reducing water removal rate and consequent decrease of the bio-drying index. The bio-drying system maintains more microorganisms active by inoculating with thermophilic bacteria to produce heat when it reaches above 55 °C to enhance the temperature cumulation and ΣF·ΔP to remove moisture and shorten the bio-drying time rapidly. The results showed that the percentage of the thermophilic period (T ≥ 55 °C) and hyperthermophile period (T ≥ 70 °C) of the hyperthermophilic pile was 67.16% and 30.14%, respectively. In comparison, only the thermophilic period of 5.48% existed in the conventional pile. The moisture content of the hyperthermophilic pile decreased from 51.23% to 41.52% in 12 days and decreased from 50.25% to 41.35% in 21 days that in the conventional pile. Meanwhile, the hyperthermophilic pile had a faster VS consumption rate and higher bio-drying index than the conventional pile. The microbial community composition showed that the hyperthermophilic pile mainly comprised thermophilic bacteria, such as Thermopolyspora, and hyperthermophilic bacteria, such as Thermus. The full-scale operation in the plants showed that the sludge inoculated with thermophilic bacteria reached the bio-drying requirement within 12 days with a maximum temperature of 94 °C, which significantly shortened the time of bio-drying and increased the sludge treatment capacity. [ABSTRACT FROM AUTHOR]

The feasibility of using hyperthermophilic biodrying (HB) technology for sewage sludge biodrying was investigated in this study. Compared with conventional biodrying (CB), HB has significantly enhanced water removal rate. It was found that proteins and lipids were degraded rapidly in the early stage of HB, while hemicellulose and cellulose became the dominant source of nutrition for microorganisms after the thermophilic phase. HB degraded more organic matters than CB and expedited the volatile solids (VS) convert to dissolved organic matters (DOM) during the 21-day biodrying. The protease activity of HB increased quickly in the first three days. In addition, the bacterial community structure of HB changed dramatically in the thermophilic phase, and diversity of bacterial community decreased. These results not only indicated that HB was a promising biodrying technology, but also revealed the potential microbial degradation mechanism of organic matters in HB process. [ABSTRACT FROM AUTHOR]

Moisture removal during bio-drying with an auto-controlled aeration system was investigated under four combined aeration strategies for a set range on exhaust gas temperature and air-flow direction. The exhaust gas temperature was kept stable within the set range by varying the air-flow rate under upward aeration, although there was a horizontal temperature gradient in the waste layer, irrespective of air-flow direction. This aeration system enhanced drying performance such that 74.7% of initial moisture weight was removed for 14 days, on average. Moreover, inversion of the air-flow direction induced as much uniformity of the vertical moisture distribution as turning the waste matrix. We evaluated moisture removal in the bio-drying process in terms of performance and efficiency and confirmed that the air-flow rate significantly affected both indicators. To achieve rapid and efficient moisture removal during bio-drying, it is important to control the air-flow rate in response to the exhaust gas temperature to fully utilize metabolic heat for evaporation. [ABSTRACT FROM AUTHOR]

This study aims to identify and evaluate the spatial distribution of Cultural Ecosystem Services (CES) benefits perceived by people in both urban and rural areas. A public participation GIS (PPGIS) approach was applied with local people who responded to an online survey and mapped their important places related to CES benefits in the Kokemäenjoki area. We explore the perceived ecosystem services of the community using different infrastructure types (green, grey, yellow and blue) based on the Corine Land Cover (CLC) classes. We identified spatial patterns of mapped important places using kernel dens ity estimation and related CES benefit associations with the infrastructures using chi-square residuals. We found that CES in urban areas are provided more often when there is more than one type of infrastructure (e.g., grey and green; grey and blue), but grey infrastructures are preferred in urban areas, while blue infrastructures produce more CES benefits in rural areas. [ABSTRACT FROM AUTHOR]

The effect of temperature and bulking agents, namely sawdust (SD), wheat bran (WB), and wheat straw (WS), on bio-drying of high-solid anaerobically digested sludge (ADS) was evaluated. A mixture of dewatered ADS with municipal sludge compost product (CP) and different bulking agents was loaded into a 180-L pilot-scale reactor. Intermittent aeration of 12 L min−1 with 20 min run/40 min stop was adopted during the whole bio-drying process. After 18 to 21 days of bio-drying, volatile solids (VS) in the trials with SD, WB, and WS degraded at a rate of 86.6, 284.3, and 344.2 g kg−1 initial VS, respectively. The matrix with easier biodegradable WB and WS achieved faster and higher water removal at a rate of 692.7 to 764.2 g kg−1 initial water, and a higher temperature cumulation of 373 to 427 °C·d. Approximately 70% of the bio-generated heat consumed for water evaporation. In the trials with WB and WS, the matrix moisture content decreased to below 39%, and the weight declined by above 48%. Water removal and VS degradation contributed to 85.2 ± 3.4% and 14.8 ± 3.4% of the total weight loss, respectively. The residual WB in bio-dried products (BP) caused low germination index (GI), indicating possible phytotoxic effects in soils. WS was determined to be the best agent with significantly higher GI and lower cost compared to WB, implying promising land utilization potential of BP. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the process of biodrying of municipal solid waste from the old landfill to preparing it for pyrolysis or gasification. New aspect of this research is biodrying of waste from old landfill. Biodrying of wastes was carried out at different aeration rates (7, 35, and 175 dm3/kg dry matter/d) at two temperatures (23 and 50 °C). The research was carried out in the laboratory bioreactors of special design (lysimeters), which simulated the conditions prevailing in the landfill. The optimal conditions for reduction of moisture in waste (63.2%) has been attained for the highest aeration rate (175 dm3/kg dry matter/d) and temperature equal to 50 °C. The final moisture content of the obtained biodried product was 23% w/w. In the bioreactor, in which the greatest reduction of moisture was obtained, the total amount of produced CO2 was 44.9 gC/kg dry matter, and the biodrying efficiency was equal to 0.89. During biodrying of wastes in optimal conditions, higher heating value of waste increased from 4.3 to 11.0 MJ/kg. As a result of the performed pyrolysis of biodried waste at 900 °C, char, oil, and gas were obtained the respective yields of 47, 32, and 21% w/w. The gas emerging in the gasification process was characterized by higher heating value equal to 11.3 MJ/m3. [ABSTRACT FROM AUTHOR]

For fuelization of high moisture content sludge, efficient sludge drying technique using a drying accelerator was investigated. In the experiment, drying accelerator types and drying conditions were changed and the effect of accelerator type and/or drying condition on sludge drying behavior was evaluated by analyzing drying characteristic curve. Depending on drying accelerator type, the addition of drying accelerator did not always exert superiority in drying rate, but sludge with added acrylic resin having low glass transition temperature (DA10) demonstrated significantly enhanced drying rate. Addition of surface activating agent (SAA) instead of resin type drying accelerator also enhanced the sludge drying rate. The highest drying rate was obtained by addition of DA10 and SAA together, and the sludge drying rate has significantly been augmented at the high drying temperature condition. [ABSTRACT FROM AUTHOR]

Metabolic syndrome (MetS) comprises a cluster of risk factors that includes central obesity, dyslipidemia, impaired glucose homeostasis and hypertension. Individuals with MetS have elevated risk of type 2 diabetes and cardiovascular disease; thus placing significant burdens on social and healthcare systems. Lifestyle interventions (comprised of diet, exercise or a combination of both) are routinely recommended as the first line of treatment for MetS. Only a proportion of people respond, and it has been assumed that psychological and social aspects primarily account for these differences. However, the etiology of MetS is multifactorial and stems, in part, on a person's genetic make-up. Numerous single nucleotide polymorphisms (SNPs) are associated with the various components of MetS, and several of these SNPs have been shown to modify a person's response to lifestyle interventions. Consequently, genetic variants can influence the extent to which a person responds to changes in diet and/or exercise. The goal of this review is to highlight SNPs reported to influence the magnitude of change in body weight, dyslipidemia, glucose homeostasis and blood pressure during lifestyle interventions aimed at improving MetS components. Knowledge regarding these genetic variants and their ability to modulate a person's response will provide additional context for improving the effectiveness of personalized lifestyle interventions that aim to reduce the risks associated with MetS. [ABSTRACT FROM AUTHOR]

Excess of sludge generated during activated sludge process by various industries is causing sludge disposable problem worldwide. Sludge contains organic materials of a highly complex mixture of molecules with some toxic compounds. Thus, the harmful effect of sludge could be managed by processing of sludge and recovery of useful products. Sludge could undergo biodegradation and used for the recovery of enzymes and energy. Enzymes (amylase, alkaline phosphatase, lipase, proteases) are produced by microorganisms and released into the media to degrade organic matters of sludge. These enzymes can be extracted by means of different physical and chemical methods from activated sludge for the multifarious application. Current manuscript discussed all the methods utilized for the extraction of enzyme and their utilization in terms of energy generation. Extracted industrial enzymes are used in agriculture, dairy, detergents, pulp, paper, cosmetics, and pharmaceutics. Apart from enzyme extraction, production of energy (biofuels, electricity) is also done by key treatment of sludge. It is a compilation of current knowledge and expected competitiveness with respect to existing methods already applied in practice for enzyme recovery. This paper presents an overview of the production of valuable enzymes and various forms of energy from sludge, which is toxic and unwanted for life. [ABSTRACT FROM AUTHOR]

Water removal is one of the main objectives of sewage sludge composting to reduce the volume and mass of sewage sludge. In this study, the effect of aeration strategy and ambient temperature (summer and winter) on composting pile temperature, moisture content, and volatile solid (VS) change were studied during sewage sludge composting processes in a well-operated sludge composting plant. The results showed that the temperatures of the composting pile could remain above 55°C for more than 3 days under all conditions, which was sufficient to meet the requirement of harmless treatment. Moisture content of composting material decreased from 65%-69% to 39.2%-52.6% within 20 days, and VS decreased to about 77%. In the end of the composting process, cumulative water removal was 0.45-0.47 kg/kg in summer, which was significantly higher than that in winter (0.35-0.36 kg/kg). When the average aeration rate was fixed, aeration strategy with a smaller aeration rate and higher on/off time ratio showed more water removal than that with a higher aeration rate and lower on/off time ratio in summer, but showed reverse results in winter. [ABSTRACT FROM AUTHOR]

Biodrying has emerged recently as an energy-effective technology for converting organic wastes into solid recovered fuel (SRF). In biodrying, water removal is achieved using metabolic heat produced from microbiological degradation of organics and forced airflow to promote heat and mass transfer. Factors affecting biodrying include moisture content (MC) and free air space (FAS) of the wastes, use of bulking agents, aeration rate, mechanical turning as well as microbial activities. These factors independently or collectively determine water removal capacities of various biodrying processes. In this review article, studies on these factors are surveyed extensively and reviewed. Additionally, details of reactor configurations, operation modes, and modeling studies on biodrying are summarized. Finally, health and environmental risks and their management associated with off-gases and final products of biodrying processes are discussed. [ABSTRACT FROM AUTHOR]

This study proposes a new model of batch biodrying of sewage sludge. This model divided the matrix into two phases (gas and solid), generating 9 · N equations which were solved numerically with Matlab software. A sensitivity analysis was also performed. It was found that the model can represent the experimental trend reported in the literature for the biodrying process, such as higher temperatures (T) for higher initial moisture content (MC) and higherTdifferences at lower initial MC. The sensitivity analysis shows that the model is mainly affected by changes in parameterskh,rb,kh,sb,µmax, UA,dp,Xsb,0, andXH,0. [ABSTRACT FROM AUTHOR]

The calibration and validation of a new model of batch biodrying of sewage sludge are presented. The calibration was performed with experimental data from the literature, while the validation was performed with new experimental data. The model was successfully calibrated with experimental data, with the values of parameters falling in the range of values reported. The new model also represented the behavior of the experimental data for all the variables measured, showing that it is robust and valid for the simulated conditions. Simulations showed that continuous high aeration increased the efficiency of the process. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the factors influencing smallholder producers’ potential to sell cattle and identify marketing opportunities for sustainable beef production in South Africa. A total of 95 structured questionnaires was administered to the Ncorha and Gxwalibomvu communities in the Eastern Cape province of South Africa. Average cattle herd size per household was higher (P< 0.05) in Ncorha (13.7 ± 1.9) than in Gxwalibomvu (11.3 ± 1.9). The logit model showed that households with few members, young farmers, Christians, large cattle herds, low income levels and access to extension services had high potential to sell cattle compared with other households (P< 0.05). Beef branding (∼40% of respondents from each community), feedlotting (∼30%), group marketing (∼25%) and forward contracting (>5%) were mentioned as potential strategies for improving commercial marketing of cattle in the studied areas. Most producers (70%) indicated their potential and willingness to participate in developing a natural pasture-fed beef brand. Overall, commercial marketing of beef cattle raised on communally owned natural pastures in the surveyed areas in South Africa was largely determined by farmer’s demographic characteristics, cattle herd size and access to extension services with branding and feedlotting as the major opportunities for improving sales. [ABSTRACT FROM AUTHOR]

Biodrying is a variation of aerobic decomposition used for the mechanical–biological treatment organic substances to dry and partially stabilize residual municipal waste. This study focuses on the volume and weight reduction biodegradation of the biodrying process using municipal solid waste and the appearance of a stable, final product. The materials were placed in a reactor with invariant airflow rates of 50 L/h and initial moisture contents of 48.49–50.00%. The laboratory-scale experiments were implemented using a 36-L biodrying reactor equipped with an air supply system, a biomass temperature sensor and air sensors. To determine the effect of temperature on biodrying, the process was repeated at various temperatures between 30 °C and 50 °C. The results obtained indicated that after 13 days, biodrying reduced the volume content of waste by 32% and the final product had a high calorific value (4680 kcal/kg). [ABSTRACT FROM AUTHOR]

The effect of straw on natural solar sludge drying was investigated. As the thickness of the stack increased, the rate of water removal per unit area slightly increased and the rate of water removal per unit volume rapidly decreased. The rate of water removal increased as the accumulation of solar energy increased but decreased as the relative humidity increased. On the 23rd day, the moisture content of the dewatered sludge and the chopped straw mixture decreased from 75.2 to 45.1% at a thickness of stack of 30 cm, with an average water evaporation rate of 7.2 kg/m2d. [ABSTRACT FROM AUTHOR]

For the final disposal and reutilization of organic wastes, reduction of moisture content (MC) is essential because water contained in the organic waste generates leachate, lowers energy content, and indirectly causes odor problems. MC also directly determines the drying cost. In this study, MC of sewage sludge was effectively decreased by applying a biodrying process in which the microbial metabolic heat evaporated the water. By controlling the initial MC through air drying and its subsequent biodrying, it was found that 50–70 wt% was the optimal initial MC range for the sludge biodrying process. In this range, 33.7–47.1% of the initial water was removed by consuming 12.3–21.2% of the volatile solids (VS) initially contained in the sludge during 10 days of biodrying. When treating the same amount of raw sludge, air-dried and biodried sludge showed better performance as bulking agents than rubber and sawdust. About 55.1% of the initial water was removed from the mixture with air-dried sludge by consuming 23.8% of the initial VS and 38.3% of the initial water was lost from the sludge mixture with biodried sludge by consuming 14.0% of the initial VS during 12.1 days of biodrying. When rubber and sawdust were used as the bulking agents, only 18.2 and 16.5% of the initial water was removed, respectively. It was thought that the easily biodegradable VS contained in the air-dried sludge produced more heat and consequently removed more water. Although air-dried sludge showed better performance than biodried sludge, the use of biodried sludge as a bulking agent was thought to be more practical than air-dried sludge because biodried sludge can be used as bulking agent for the next round of biodrying in a repeated operation of the biodrying reactor. After biodrying, the lower heating value of the biodried sludge (51.5 wt% of MC) was 14.644 MJ kg−1, which was much higher than that of the original wet sludge. [ABSTRACT FROM AUTHOR]

Biodrying is a technology that makes use of bioenergy from organic waste with high water content to remove moisture and improve the utilization value and treatability of the waste. The essential feature of biodrying is the utilization of thermal energy, generated by aeration degradation of organic matter in waste, to evaporate water, thus achieving self-drying. The effectiveness of biodrying depends on the energy balance of the system, in which simultaneous heat and mass transfer are driven by biogenerated heat. We have focused on improving drying efficiency of these wastes and in this article we review the energy balance characteristics of the biodrying process. This encompasses the framework of biodrying energy balance analysis methodology, modeling expressions for energy release and utilization, and identification of the main model parameters and the main factors that affect the energy balance of the process. Finally, this review investigates possible ways to improve the efficiency of energy utilization. The heat source of the biodrying process can be calculated by combining a first-order biodegradation kinetics model of organic components with combustion heat (Hc) of biodegradable volatile solids (BVS). Heat consumption is mainly described by the enthalpy difference of the ventilation air flow through the system. The biodegradation rate and ventilation mode—which includes the ventilation rate, ventilation time, and ventilation distribution—all influence the energy balance of the biodrying system. There are some possible alternatives that can be considered in order to optimize the energy balance and improve the drying efficiency, such asoptimizing organic biodegradation, improving material physical structures, utilizing sensible heat in exhaust gas in biodrying, and utilization of external low-grade heat sources, such as solar and industrial waste heat, to assist drying. [ABSTRACT FROM AUTHOR]

Sludge bio-drying is an aeration process for the removal of water. The drying process utilizes the bio-heat generated from aerobic degradation of organic matter in sludge. In this study, four trials were run in the winter season at ambient temperatures of between 3°C and 9°C. The physical and chemical changes that occurred during the process were investigated and the impacts of the particle sizes of bulking agents and the controlled-matrix temperature were assessed. Results indicated that the process can start up in winter with a three-day lag, while the total duration was only seven days. The highest water removal rate (of 31.0%) with the least organic matter loss (of 12.2%) was obtained at a lower controlled matrix temperature (of 43°C) with a bulking agent of mixed particle size. As a common bulking agent, straw, which has a small particle size of 2–5 mm, was beneficial for organic matter degradation, while it had a negative effect on water removal. The use of different types of straw (with larger particle size of 20–30 mm) as the bulking agent gave poor performance, in which the organic matter degradation rate was 9.75% and the water removal rate was 25.9%. Higher controlled temperature (53°C) resulted in less aeration but degradation rates were enhanced to 16.8%. The using of lower temperatures (43°C) resulted in lower water removal rate (of 29.2%) and relatively lower biodegradation rate. [ABSTRACT FROM AUTHOR]

The removal efficiency (RE) profile of a complex mixture of volatile organic compounds (VOCs) was characterized in a full-scale biofilter treating odorous emissions from a composting plant in an urban environment. The biofilter was composed of two similar units packed with mixtures of pine bark and wood chips, and were operated in parallel. Up to 48 different VOCs were identified by gas chromatography-mass spectrometry (GC-MS) and individual RE values were calculated by comparing influent and effluent GC-MS chromatograms. Multivariate correlations on RE, the partition coefficients between octanol/water (KOW), octanol/air (KOA), and water/air (KWA), as well as biodegradability and toxicity estimates, were estab- lished by Principal Component Analysis (PCA). Biofilter RE values were positively and negatively corre- lated to KOA and to KWA, respectively, indicating that hydrophobic volatile compounds were more effi- ciently removed than the hydrophilic ones. Instead, RE was poorly correlated with estimates of the VOCs fast aerobic biodegradation. Substrate mass transfer (adsorption on the hydrophobic packing/biomass), rather than biodegradation rates, appears to be the main process governing the efficiency in conventional air biofilters applied for the treatment of odorous emissions. [ABSTRACT FROM AUTHOR]

A massive characterization in terms of respiration activity for the most common types of organic solid wastes is presented in this compilation. Respiration activity for a solid waste is a crucial parameter to understand the behaviour of the waste in the environment and for waste management aspects such as the definition of a suitable biological treatment and the determination of the potential rate of microbial self-heating if organic wastes are to be used as solid recovered fuels. The respiration data compiled in this work are the result of five years of research focused on the determination of the biological activity of organic wastes. A compilation of respiration data found in the literature is also presented. The main groups of organic wastes analyzed are: municipal solid wastes (including mixed wastes and source-selected organic fraction), wastewater sludge (including digested and non-digested sludge from primary and secondary operations in municipal and industrial wastewater treatment plants), different types of manure (of different origin), other particular wastes (animal by-products, hair waste, fats, etc.) and some mixtures of different wastes. Results suggest that respiration activity can be used to classify the biodegradability of organic wastes into three main categories: i) highly biodegradable wastes (respiration activity higher than 5 mg O2 g Organic Matter-1 h-1), which includes source-selected organic fraction of municipal solid waste, nondigested municipal wastewater sludge and animal by-products; ii) moderately biodegradable wastes (respiration activity within 2 to 5 mg O2 g Organic Matter-1 h-1), including mixed municipal solid waste, digested municipal wastewater sludge and several types of manure; iii) wastes of low biodegradability (respiration activity lower than 2 mg O2 g Organic Matter-1 h-l), which includes few organic wastes such as some particular wastes from the food industry. [ABSTRACT FROM AUTHOR]

The move from disposal-led waste management to resource management demands an ability to map flows of the properties of waste. Here, we provide a comprehensive review of how mechanical-biological treatment (MBT) plants, and the unit processes that comprise them, perform in relation to management of material flows, while transforming inputs into output fractions. Focus is placed on the properties relating to the quality of MBT-derived fuels. Quality management initiatives for refuse-derived fuels (RDF) or solid recovered fuels (SRF) are reviewed and SRF quality from MBT plants is assessed through a statistical analysis of published data. This can provide a basis for a targeted reduction in pollution load from solid MBT outputs and subsequent end-user emissions. Our analysis, among else, (1) verifies the difficulty of chemical separation solely by mechanical means; (2) illustrates the trade-off between achieving a high quality of recoverable outputs and the quantity/properties of reject material; and (3) indicates that SRF quality could respond to legislative requirements and market needs, if specific improvements (reduction of Cl, Cu, and Pb content) are achieved. Further research could enhance the confidence in the ability of MBT plants to produce a quality-assured SRF suitable for specific end-users, without contradicting the wider requirement for an overall sustainable management of resources. [ABSTRACT FROM AUTHOR]

To investigate the effect of control parameters (moisture, aeration and C/N ratio) on the composting evolution (temperature, pH, O2 and volatile compounds (VCs)) of municipal solid waste and pine trimmings, a central composite experimental design was used. The ANFIS modelling obtained shows that all the independent parameters were clearly influenced by the studied parameters. The relative influence of the other independent variables on temperature was C/N > moisture > aeration. However, for pH, O2 and VCs followed the order C/N > aeration > moisture. Moreover, the results were concordant, with a positive relation between temperature and VCs. In this way, lower VCs contents in ambient atmosphere have been found by using medium-to-high aeration (< 0.1 lair kg-1 min-1), medium-to-high C/N (60-77) and high moisture (> 55%). [ABSTRACT FROM AUTHOR]

In agreement with the new European Union directives concerning the valorization of materials and energy recovery, Municipal Solid Waste (MSW) management is, in general based on an integrated approach characterized by a combination of different treatment processes. The bio-mechanical treatment (BMT) of MSW is an increasing option in Europe either as a pre-treatment before landfilling or as a pre-treatment before combustion. In this context the research on the bio-drying process is not fully developed. In the present paper the Lower Heating Value (LHV) dynamics during MSW bio-drying has been assessed. Measurements were made using a pilot scale bio-dryer that allows the recording of data as air flow, temperature (at the entrance, at the exit and inside the waste), and weight loss. An initial characterization of the MSW completes the input data. Results give information on the dynamics of the main process parameters (humidity, volatile solids, ammonia, Lower Heating Value) and also of additional parameters. [ABSTRACT FROM AUTHOR]

Effective sludge management is increasingly critical for pulp and paper mills due to high landfill costs and complex regulatory frameworks for options such as sludge landspreading and composting. Sludge dewatering challenges are exacerbated at many mills due to improved in-plant fiber recovery coupled with increased production of secondary sludge, leading to a mixed sludge with a high proportion of biological matter that is difficult to dewater. Various drying technologies have emerged to address this challenge of sludge management, whose objective is to increase the dryness of mixed sludge to above critical levels (≈42% dryness) for efficient and economic combustion in the boiler for steam generation. The advantages and disadvantages of these technologies are reviewed in this article, and it is found that many have significant technical uncertainties and/or questionable economics. A biodrying process, enhanced by biological heat generation under forced aeration, is introduced that has significant promise. A techno-economic analysis of the batch biodrying process at a case study mill showed an annual operating cost savings of about $2 million, including the elimination of landfilling practices and supplemental fuel requirements in the boiler. It was shown that if a biodrying residence time of less than 4 days can be achieved, payback periods of 2 years or less can result in many mills. The potential for the development of a continuous biodrying reactor and the fundamentals of its mathematical modeling are thus presented. Compared to the batch reactor configuration, it is expected that the continuous process would result in improved process flexibility and controllability, lower investment and operating costs due to shorter residence times, and an improved potential to fit into the crowed pulp and paper mill site. [ABSTRACT FROM AUTHOR]

Discusses a study that compared different respirometric methods with particular attention to the definition of biological stability. Background on dynamic respiration index; Extraction of dissolved organic matter; Correlation matrix for respirometric determinations and dissolved organic carbon fractions.

Monitoring was carried out during summer 1997 along a selected area of the Tyrrhenian coast near the Tiber river mouth. Fifty-eight seawater samples, collected from 19 stations, were examined for coliforms, streptococci, Enteroviruses, Salmonellae, coliphages, Bacteroides fragilis phages, Pseudomonas, alophilic Vibrios, Aeromonas and yeasts. Salmonellae and coliphages were isolated in 3 and 12 out of 58 samples, respectively. Enteroviruses and Bacteroides fragilis phages were not isolated. Reoviruses were isolated only from 2 out of 58 samples. A limited number of samples of the northern stations located near the Tiber and other river mouths exceeded the guide values for bathing water by the EU Directive. All the southern stations, located near canals, were of very good microbiological quality. Pseudomonas, Vibrio, Aeromonas and yeasts were isolated from all stations and their values in 100 ml of seawater were 10-10[sup 6], 10-10[sup 6], 0-10[sup 6] and 1-10[sup 3], respectively. An extensive disinfection practice carried out on domestic wastes, which are discharged in rivers and canals, probably brought pollution levels of most stations to values within the bacterial standards. The spread of Pseudomonas, Aeromonas, etc. showed that all the coastal area studied was characterized by the presence of organic matter coming from land that can support the presence of opportunistic pathogens and other microbial flora. [ABSTRACT FROM AUTHOR]