Iwa international Specialist Conference
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- Bu səhifədəki naviqasiya:
- Introduction
- Enhancement of biosolids quality
- Full-scale experience with thermophilic anaerobic digestion
AbstractA large market study was undertaken in France over biosolids quality. The partnership involved the French Environment Ministry, AGHTM, Ademe and the 3 french utilities : Vivendi, Ondeo and Saur. The focus was set on what makes biosolids of agronomic quality. The answer is a respect of regulation for metal and organic trace elements. That respect is directly correlated to two different fields:
Today, most laboratories have adopted principles of good laboratory practices and have gained an accreditation for the analyses they propose. In respect to biosolids analyses, they have set up methods to indicate if any element is above or below the threshold set by the regulation. However, the results they give for a biosolids quality are interpreted in different ways depending on the person concerned. They can be read as:
The difficulty in the interpretation of analytical results is that the details given, or not, with the analytical result (limit of quantification, uncertainties, …) will impact strongly on the interpretation that can be made from it. A standardisation in the expression of analytical results could be useful together with any analytical method standardisation. In parallel, WWTPs operators have integrated a strong will of quality and good practices in their ways of operation in the past years. Many actions were implemented in order to have a fully integrated system management from a close control of industrial discharges in sewers to good practices in biosolids conditionning and handling up to the soil. Producing a biosolids of recognised agronomic quality is the key objective of biosolids analytical characterisation. However, once the production of biosolids of agronomic quality has been shown at a plant, it would be interesting to be able to demonstrate a constant or even an improved agronomic quality of biosolids over time. The analytical methods could be, for that specific application, more sensitive. It would be interesting to know if in many occasion, the biosolids content in some elements arrived at a minimum or if it can still be lowered. It would be interesting to have the two ways and will of good practices from the laboratories and from WWTP operators work now together rather than in parallel.
Emmanuel ADLER . Club ATOUTBOUES - ACONSULT Toute l'info de l'organique sur le site www.atoutboues.fr.st Centre d'Affaires des Monts d'Or 69 290 St Genis les Ollières France Tel : (33) 04 78 57 3939 --- Fax : (33) 04 78 44 8074 mail : Emmanuel Adler The paper I want to present will assess the role of concertation in sludge management issues, particularly regarding scientific issues such as standardization in international groups (CEN-TC, DG Env...) but also local negotiating procedures. On one hand will be demonstrate the strong need for scientifical coherence through various example (limits for land recycling for sludges versus compost, analytical procedures inadequate between various countries). On the other hand, through various angles (history, sociology, case studies and international comparisons) we should demonstrate that non scientifical issues are becoming more important than technological data. Therefore, it is now needed to elaborate new ways to assess the solution finding procedure for domestic waste management. Between agronomic, thermic or storage solutions, the basic citizen is only concerned by is own comfort and health and does not care so much about the techno issue. What the basic citizen needs is not yet provided by decision makers and has yet to be created : that's the new challenge for engineers !
30. ABSTRACT Production of Class A Biosolids With Anoxic Low Dose Alkaline Treatment and Odor Management Issues M. Abu-Orf1; J. Brewster2, J. Oleszkiewicz2, R.S. Reimers3, P. Lagasse4, B. Amy4; D. Glindemann5 1North American Technology Center, USFilter/Vivendi Water, Vineland, NJ, USA, 2University of Manitoba, Department of Civil Engineering, Winnipeg, MB, CAN, 3Tulane University, New Orleans, LA, USA; 4City of Winnipeg, Water & Waste Department, Winnipeg, MB, CAN, 5Virginia Tech, Blacksburg, VA, USA More than three million tones of municipal sludges (known as biosolids) are land applied in the US. The demand on producing a Class A (pathogen free) biosolids in the U.S. is increasing in light of recent publications that criticize the use of Class B biosolids for land application. Thus, treatment plants will be looking into producing high quality biosolids, however, the cost might hinder such efforts. Winter land application of biosolids may soon be banned resulting in storing biosolids for longer periods prior to application. This project used this storage time as an opportunity to achieve further disinfection of biosolids after alkaline addition. The project defined and quantified the abiotic factors leading to pathogen inactivation over long-term anoxic storage with various additions of alkaline material. Previously, the role of indigenous ammonia, high pH, and other factors in pathogen inactivation were quantified using a series of bench scale tests to determine the mechanism of inactivation. In these experiments, the synergistic effects of high pH and free ammonia, under different storage conditions, were studied. The identified treatment regimes were then verified in full-scale studies in order to determine the rates for achieving a Class A biosolids over time, under naturally changing conditions following low dose alkaline treatment. The feasibility of full-scale anoxic disinfection of dewatered and digested biosolids from Winnipeg, Manitoba with low lime doses and lagoon fly ash was investigated to determine if a Class A product could be produced. Lime doses of 50g, 100g, and 200g per kg of biosolids (dry) were used along with fly ash doses of 500, 1000, and 1500g per kg of biosolids (dry). Mixing was conducted with Lodige mixer (USFilter/Asdor), which is specifically designed to mix biosolids with lime and fly ash. The mixed product was buried in eight-10 cubic meter trenches outdoors at the West End Water Pollution Control Center in Winnipeg. The trenches were backfilled with earth and covered with a tarpaulin to simulate anoxic conditions. Sampling cages were packed with the mixed and treated biosolids and pathogens, which are non-indigenous to Winnipeg’s biosolids. The cages were buried with the mixed biosolids in the trench. The non-indigenous pathogens spiked in the laboratory were the helminth Ascaris suum and the enteric reovirus. Samples were removed at days 12, 40, and 69 during the fall of 2001 and again in the spring and summer of 2002 at days 292 and 356 days. The samples were tested for the presence of fecal coliform, Clostridium perfringens spores, Ascaris suum eggs, and reovirus. The pH, total solids, and free ammonia content of the mixed product were also determined for each sample. The paper will present the results from the full-scale trench study. Fecal coliform bacteria and reovirus were completely inactivated for doses as low as 100g lime per kg biosolids (dry) and 50g lime + 500g fly ash per kg biosolids (dry) by the first sampling period (12 days). Spores of the bacteria C. perfringens experienced a 4-log reduction when treated with 100g lime per kg biosolids and a 5-log reduction when treated with doses as low as 50g lime + 500g fly ash per kg biosolids (dry) after 69 days. Ascaris eggs were completely inactivated when treated with doses as low as 50g lime + 1000g fly ash per kg biosolids (dry) after 291 days of storage. Class A criteria were met for all treatments containing at least 50g lime – amended with 1000g fly ash - per kg of dry biosolids by the 291st day of storage. The concept from this full-scale project is currently under consideration at a USFilter Operated Facility (Franklin City, OH). However, it is anticipated that odor may constitute a concern at this facility and others. Although, the trenches will be covered to assure anoxic conditions and little odor is expected to be experienced during storage, odor is a concern once the trenches are opened after the stabilization storage time to transfer the biosolids to land application. Samples from the different trenches were collected at two different times and odorants were quantified from these samples at Virginia Tech laboratory. Odor from limed biosolids is primarily from two sources: amine and reduced sulfur compounds. We analyzed the following compounds: Trimethyl Amine TMA, Methane Thiol), Carbon Disulfide CS2, Dimethyl Disulfide DMDS, Dimethyl Sulfide DMS, Dimethyl Trisulfide DMTS) and H2S The North American Technology Center (NATC) of US Filter/Vivendi Water carried two research programs in the past two years for odor mitigation from dewatered biosolids, targeting amines and reduced sulfur compounds. For reduced sulfur compounds, our research has been focusing on using nitrate salts and anthraquinones for reducing organic sulfur compounds. We have conducted experiments on limed biosolids at the Blue Plains Wastewater Treatment Facility in Washington DC and Philadelphia Water Department Wastewater Treatment Plant and other plants. The work showed we could control and significantly reduce reduced sulfur compounds by using a commercially available product (Bioxide-AQ), which is a mixture of calcium nitrate and anthraquinone particles. The Blue Plains is considering using this technology to reduce sulfur odor during lagoon storage and land application, and in the fall of 2002, we will be conducting full-scale demonstration for this purpose. The paper will present main results from bench scale and full-scale trials. From the odor analysis of biosolids samples from the trenches, we have seen trimethyl amine (TMA) in large amounts in the lime and fly ash-stabilized biosolids. It is expected that actual plants to use such a combination to obtain class A product. TMA is a masking fishy odorant. The existence of TMA is a universal problem to all lime stabilized biosolids. The NATC research revealed that TMA generation is primarily due to chemical degradation of polymers used during biosolids dewatering. The TMA generation is due to the high pH generated when using alkaline stabilization since it will alter the chemistry of trimethyl ammonium (soluble compound) to TMA in the headspace. One solution to mitigate TMA generation is to condition sludges with non-acrylamide polymers, which we are currently investigating in anaerobic sludge dewatering. The research on understanding the amine odors was conducted at the University of Delaware and again, the paper will present relevant results to mitigation of alkyl amine odors from limed biosolids.
Institute of Chemical Technology, Technická 1905, 166 28 Prague, Czech Republic IntroductionThe principal benefits of anaerobic digestion are that the sludge is stabilized to an innocuous and easily dewatered substance - biosolids, the energy is produced in the form of biogas, the quantity of solids and the volume of sludge requiring disposal are reduced, and the inactivation of pathogenic microorganisms is also accomplished. The final product is stable, harmless material that can be used as a soil conditioner or fertilizer. The pathogen level, volatile solid content, and the concentration of heavy metals in the residual sludge are the principal concerns in considering the land disposal of sludges. The destruction of solids is usually about 25 - 50 % of the feed sludge solids and can result in the reduction of the cost of final disposal. Biosolids with a markedly reduced odor can be stored indefinitely without putrefaction. It contains nitrogen and phosphorus compounds and other nutrients as well as residual organic material that can improve the fertility and texture of soil. Significant inactivation of pathogens occurs during the anaerobic digestion dependent on the process temperature and technological arrangement. The disadvantage of anaerobic sludge digestion is the quality of the supernatant from treated sludge thickening and dewatering. It contains suspended solids, dissolved and particulate organic materials, high concentration of ammonia nitrogen, some phosphorus and other compounds. This return flow increases the loads of the solids, oxygen demand and nutrients of the wastewater treatment system. Enhancement of biosolids qualityPretreatment for the better biodegradability The methanogenic process limitation by the rate of the hydrolysis of suspended organic matter is of particular importance during the anaerobic treatment of solid wastes and sludges. By means of an efficient pretreatment the substrate can be made better accessible for the anaerobic bacteria, optimizing the methanogenic potential of the waste to be treated. The objective is to accelerate the digestion of input sludge, rise the degree of degradation, and thus to decrease the amount of sludge to be disposed. The improvement of the biodegradability of particular substrate is mainly based on a better accessibility of the substrate for enzymes. There are several methods how this can be accomplished: - mechanical methods - the disintegration and grinding of solid particles present in sludge; - ultrasonic disintegration; - chemical methods - the destruction of complex organic compounds by means of strong mineral acids or alkalis; - thermal pretreatment - thermal hydrolysis is able to split and decompose a remarkable part of the sludge solid fraction into soluble and less complex molecules and significantly contributes to pathogens destruction. Intensification of the process Staging and a higher operation temperature can intensify the process. The main contribution of thermophilic temperature to the sludge treatment is concerned with the higher stability for solids reduction of the thermophilic anaerobic digestion in comparison with the mesophilic one, the higher biogas production, the improvement of the energy balance of the treatment plant, the high resistence of thermophilic digester to foaming, with no problems with odour of thermophilic biogas and the higher effect of destroying pathogens in the thermophilic digester. In the two-stage system the acetogenic and methanogenic processes are not separated and take place in both reactors, but the stages can differ in the temperature. The first or the second stage can be operated at thermophilic conditions, improve the efficiency in destroying pathogens and decrease residual organics. Also a combination of thermophilic aerobic digestion with mesophilic anaerobic process in the second stage (dual system) can be used. If acidogenic and methanogenic processes are separated (each of them takes place in different reactors) we are speaking about a „two phase process“ or „phase separation“. By integrating of acidogenic reactor to the process we can save the reactor volume. In the temperature-phased process the acidogenic reactor is operated at thermophilic temperature. The feeding frequency, the mixing efficiency and the guaranteed retention time are also very important and we can differentiate intensive and extensive thermophilic process. Co-digestion and co-fermentation Common digestion of mixed different materials (e.g. municipal sludge, agricultural wastes, wastes of food or pharmaceutical industry, organic fraction of municipal solid wastes etc.) can improve overall efficiency and biogas yield because of higher substrate diversity and consequently cause better utilization of reactor volume. In the case of difficult degradable material, an addition of easy degradable substrate can improve degradation on the molecular level and couple the degradation pathways bringing the higher energetic yield and better degradation of problematic compounds. Full-scale experience with thermophilic anaerobic digestionOur experience is based on the full-scale applications to the three wastewater treatment plants with different ways of transferring process temperature – the long-term adaptation with a full loading rate and the slowly increasing temperature, and the quickly increased temperature and slow increasing loading rate in the other case. The main reason for applying thermophilic temperatures was the better sanitizing effect of the higher process temperature and the need for more digesting capacity and more energy. The microscopic observation proved the more efficient destroying of filaments in thermophilic sludge and thus a less susceptibility to foaming. Thermophilic sludge with the mean residence time of 5.1 days was not able to reach the class A biosolids, but the relative frequency of samples meeting this limit was 40 %. The insufficient hygienization effect was probably influenced by a lower real mean retention time caused by inadequate mixing. Results of assessment of indicator bacteria removal kinetics in laboratory batch experiments with the same input raw sludge and anaerobic sludge showed 3 days of reaching Class A even for higher resistant enterococci. The proposed better mixing in digesters will increase the real retention times and could also improve pathogens removal rate. 32. Bioprocessing of sewage sludge for safe recycling on agricultural land Jens Ejbye Schmidt, Damien Batstone, Nina Christensen & Irini Angelidaki Environment & Resources DTU, The Technical University of Denmark Building 115 E-mail: jes@er.dtu.dk, Phone: + 45 4525 1454 The intensive use of wastewater treatment in Europe has resulted in production of huge amount of sewage sludge. There are currently over 50.000 wastewater treatment plants operating in the European Union, yielding a total of about 7.9 millions tons of dry solids in year 2000. The amount of sludge will continue to increase as the Urban Wastewater Treatment Directives continues to be implemented. There have been several disposal routes for sludge, including ocean dumping, incineration, spreading on agricultural land, soil incineration, land re-vegetation, land reclamation, land spreading in forestry or land filling. At present the disposal of sludge by land filling is accounting for 40% of the waste and is the most important way for treatment in EU followed by spreading on land accounting for 37% of the sewage sludge produced. The amount of sewage sludge requiring disposal is expected to increase significantly in the future due to recent environmental developments. With increasing sludge protection in the EU the wastewater industry will seek to recycle larger amounts of sewage sludge for agricultural purposes. This approach seems to be reasonable since agricultural land becomes nutrient deficient if not adding fertilizer due to the intensive cultivation used in modern agriculture. Hence, bioprocessed sewage sludge application on agricultural soil will diminish the use of artificial fertilizer. Man-made chemicals of organic origin are found widespread in the biosphere as contaminants, and their adverse effects on human health and other biological life have received increasing attention in the European Union. Many organic contaminants have broad spectrum of use in the society and a major part will eventually end up in for example sewage sludge from municipal wastewater treatment plants. Recent findings have detected organic contaminants in municipal sewage sludge in such concentrations that they appear toxic to many organisms due to direct exposure or due to biomagnification within the food web. The compounds have adverse effects on biological life and some of them are carcinogenic and mutagenic. Also estrogenic effects caused by some of these contaminants in sludge have been observed on aquatic organisms lately, and a deterioration of human fertility is suspected. Therefore, the aim of modern sewage sludge treatment must be the use of all resources in the sewage sludge and, therefore, it is crucial to recycle waste to the environment after it has been freed from pollutants. Consequently, modern sewage sludge treatment has to be designed for treatment of organic contaminants. Potentially hazardous compounds are found in sewage sludge from municipal and industrial wastewater. An efficient removal of these pollutants is a prerequisite for recycling waste into the natural resource cycle. We will present results showing different application of aerobic, anaerobic and combination of aerobic and anaerobic for bioprocessing of the sewage sludge to ensure optimal detoxify of the sewage sludge. Also the use of bio-augmentation for decontamination of the sewage sludge wastes in the bioprocessing procedure will be presented. The following compounds will be in focus: Emulsifying agents as nonylphenols and nonylphenol ethoxylates (NPE), polycyclic aromatic hydrocarbons (PAHs) derived from incomplete combustion processes, and phthalates, which are used as additives in plastics and surfactants such as linear alkylbenzene sulfonate (LAS). 33. BIOSOLIDS 2003 – Wastewater Sludge as a Resource ABSTRACT Full scale validation of helminth ova (Ascaris suum) inactivation by different sludge treatment processes. B. Paulsrud1), B. Gjerde2) and A. Lundar1) 1) Aquateam – Norwegian Water Technology Centre, Oslo 2) Norwegian School of Veterinary Science, Oslo The Norwegian regulation on sewage sludge treatment and disposal, effective from January 1995, requires both stabilisation and disinfection (hygienisation) of all sludges to be applied on agricultural land or on green areas. The sludge should meet the following criteria for disinfection: No Salmonella sp in 50 grams of sludge No viable helminth ova Less than 2,500 faecal coliforms per gram dry solids
The full scale tests were carried out by exposing permeable filter bags containing Ascaris ova for actual operating conditions (different time-temperature relationships). For the lime treatment plant, we experienced that due to the granular consistency of the limed sludge, the ova in the filter bags were not exposed to the high pH (but only to the increased temperature). Therefore, the full scale tests will be supplemented by a comprehensive laboratory test set up, in order to determine the critical lime dosages at different dry solids content of the dewater Yüklə 0,66 Mb. Dostları ilə paylaş:
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