The use of renewable energy is becoming increasingly necessary in order to address the global warming problem and, as a consequence, has become an high priority for many countries. Biomass is a clean ...and renewable energy source with growing potential to replace conventional fossil fuels. Among biomass, residual and waste ones represent a great resource for energy generation since they permit both to eliminate a possible waste and to produce energy. In the present work, the case of slaughterhouse wastes (SHWs) has been investigated. Anaerobic digestion is nowadays considered as one of the most important and sustainable conversion technology exploiting organic matter and biodegradable wastes. Biogas results from this bio-chemical process and mainly consists of methane and carbon dioxide, leading to produce thermal energy and/or electricity. In this paper, the European Regulations on animal by-products (ABPs) are described, and some previous study on anaerobic digestion and co-digestion of ABPs - more precisely SHWs - are considered and compared in order to fix a starting point for future tests on their co-digestion in a micro-scale pilot digester. This is to define optimal feed ratio values which ensure an increasing content of methane in the outgoing biogas.
This paper is a follow up of one presented by Otterpohl
et al. (1997) in
Water Science & Technology. This extension emphasises the responsibility of the professionals in waste- and wastewater ...management for future development. It shows a lists of 10 technological options for sanitation with source control. The political discussion about future sanitation systems seems to lack input of those working on further development. Even Agenda 21 is a complete failure in this respect − sadly, in a core subject for survival of future generations. The main task of sanitation besides highest hygienic standards is to keep soil fertile.
Sanitation with the mixing up of food and water cycles washes all those substances out to the seas that are extremely harmful there (accumulation) and extremely necessary on the land (depletion of fertility and fossil resources). New integrated sanitation and waste management systems will mostly have to respect different qualities of matter from human settlements: blackwater with biowaste, greywater, stormwater runoff and non-biodegradable waste. Based on this distinction, nine differentiating and one mixing systems with resources management are presented. Some of them require careful examination in selected pilot projects.
Taking into account the physical-chemical characteristics of the SC-OFMSW processed at Valorsul's anaerobic digestion plant, the influence of seasonal effects was studied. The waste presents a good ...quality, with a putrescible content of around 90%. In terms of chemical characteristics, the waste composition is similar to the one referred in the literature. The results show that seasonal variations seem not to affect the SC-OFMSW characteristics. The waste is very soluble and for that reason the solids content in the digester is low (TS in the digestor is 2.8%). The production of biogas is higher than the one predicted in the design operational parameters. Consequently, smaller quantities of compost are produced.
Biological treatment processes including anaerobic digestion (biogasification) and composting are increasingly being considered by waste management officials and planners as alternatives for managing ...the mainly organic residues of municipal solid wastes (MSW). The integrated waste management model which is based upon the application of life-cycle analysis was employed to compare the environmental burdens of landfilling, composting and anaerobic digestion of MSW at a mid-sized Canadian community. Energy consumption (or recovery), residue recoveries and emissions to air and water were quantified. Scenario comparisons were analyzed to demonstrate that the environmental burdens associated with anaerobic digestion are reduced in comparison with the alternative options. The major benefit occurs as a result of the electricity produced from burning the biogas and then supplying the 'green power' to the local electrical grid.
Disadvantages of the traditional sanitation concept of industrialized countries are discussed and more sustainable systems are explored. The usual approach required too much water, diluted faeces and ...raised nutrient levels in receiving waters. New sanitation concepts began by considering waste and wastewater in 4 groups: faeces and urine; grey water; stormwater; and non-biodegradable solid waste. A more sustainable sanitation strategy for urban areas involved the separation of faeces and urine and their treatment with other biodegradable waste; decentralized aerobic treatment of grey water in constructed wetlands; and infiltration of stormwater. There were many advantages in terms of energy use, pollution of receiving waters and intensity of material use. The major disadvantage of the approach was its incompatibility with the sanitation systems of industrialized countries. Performance and actual costs would be estimated from the results of a pilot scheme involving 300 people in Lubeck, Germany.
Anaerobic co-digestion of organic wastes from households, slaughterhouses and meat processing industries was optimised in a half technical scale plant. The plant was operated for 130 days using two ...different substrates under organic loading rates of 10 and 12 kgCOD.m(-3).d(-1). Since the substrates were rich in fat and protein components (TKN: 12 g.kg(-1) the treatment was challenging. The process was monitored on-line and in the laboratory. It was demonstrated that an intensive and stable co-digestion of partly hydrolysed organic waste and protein rich slaughterhouse waste can be achieved in the balance of inconsistent pH and buffering NH4-N. In the first experimental period the reduction of the substrate COD was almost complete in an overall stable process (COD reduction >82%). In the second period methane productivity increased, but certain intermediate products accumulated constantly. Process design options for a second digestion phase for advanced degradation were investigated. Potential causes for slow and reduced propionic and valeric acid degradation were assessed. Recommendations for full-scale process implementation can be made from the experimental results reported. The highly loaded and stable codigestion of these substrates may be a good technical and economic treatment alternative.
This report proposes a new set of guidelines for the characterization of municipal solid waste. It is based on an analysis of reference methodologies, used internationally, and a case study of ...Valorsul (a company that handles recovery and treatment of solid waste in the North Lisbon Metropolitan Area). In particular, the suggested guidelines present a new definition of the waste to be analysed, change the sampling unit and establish statistical standards for the results obtained. In these new guidelines, the sampling level is the waste collection vehicle and contamination and moisture are taken into consideration. Finally, focus is on the quality of the resulting data, which is essential for comparability of data between countries. These new guidelines may also be applicable outside Portugal because the methodology includes, besides municipal mixed waste, separately collected fractions of municipal waste. They are a response to the need for information concerning Portugal (e.g. Eurostat or OECD inquiries) and follow European Union municipal solid waste management policies (e.g. packaging waste recovery and recycling targets and the reduction of biodegradable waste going to landfill).
In this paper, performance of two high rate technologies, upflow anaerobic fixed-film reactor and fluidized bed laboratory-scale, treating distillery wastewater (wine vinasses) at anaerobic ...thermophilic conditions have been compared. The results obtained show that the stationary packed bed, with a corrugated plastic support, operated under stable conditions at organic loading rates (OLR0) around 20 kgCOD/m3/d, gives maximal total CODr of 76% at OLR0 of 6.29 kgCOD/m3/d; the fluidized bed reactor, operated on open pore sintered-glass media, gives total CODr of 96% at OLR0 of 5.88 kgCOD/m3/d. The anaerobic fluidized bed technology is more effective than the upflow anaerobic fixed-film technology due, fundamentally, to this technology favouring the transport of microbial cells from the bulk to the surface and enhancing the contact between the microorganism-substrate phases, In this sense, the stationary packed bed technology is adequate for the treatment of easily biodegradable wastewater, or for the cases where elevated percentages of CODr removal are not required, while the fluidized bed technology is especially suitable for treatment of hazardous wastes with recalcitrant compositions.
It is possible to use co-fermentation to increase biogas production considerably in digesters with free capacity. Also, the energy production increases by increasing biogas production. Many ...co-substrates such as energy crops, biodegradable waste from the food industry, restaurants and public parks, etc. are on the market. Water consumption is decreasing because of population movement and a decreasing population size because of a drop in the birth rate. Therefore, capacities in digesters will increase and new uses for this capacity are needed. Co-fermentation could be one solution. Useful co-substrates should be identified by material characteristics. It is important to assess suitability of materials for fermentation in small-scale tests, and to gain experience particularly with regard to the handling, the compatibility of the biocoenosis in the digester and the effects of returning effluent to the activated sludge process. A test period with fat separator contents has started at the wastewater treatment plant, Waßmannsdorf, Germany. Biogas production and methane content increased compared to the reference cascade without co-substrate input.
The adsorption of the textile dyes Basic Blue 41, Aniline Blue, Reactive Black 5 and Mariposa Blue was studied from model solutions prepared in distilled water in the concentration range up to 2000 ...mg 1-1. Biodegradable wastes were used and are proposed here as adsorbents due to their abundance and inexpensiveness in the authors' country. The influence of the particle size, pH, presence of an electrolyte in the dye solution, adsorbent activation and competition in ternary dyes mixtures was determined in this study. Adsorption capacity of the adsorbents designated as HOMAP and POMAP with particle diameter less than 3 mm for the Basic Blue 41 dye was found to be 154 and 77 mg g-1, respectively. The efficiency of the prepared adsorbents for removing basic, acid and reactive dyes with a concentration of 400 mg 1-1 was examined. A comparison of the adsorption capacity and desorption feasibility of the adsorbents was made. The basic dye was adsorbed with efficiencies varying from 87-98%, the reactive dye was removed in the range 60-98% and the add dye, 60-70% by three of the four adsorbents tested in this study. The determination of adsorption equilibrium concentrations was followed by HPLC with diode array detection.
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