|ognizant Communication Corporation|
A Journal of Science Serving Legislative, Regulatory, and Judicial Systems
Human Advancement · Environmental Protection · Industrial Development
Technology, Vol. 10
Copyright © 2008 Cognizant Communication Corp.
Emerging Pretreatments for Enhanced Digestion of Biosolids
Department of Civil Engineering, University of Ottawa, Ottawa, Ontario, Canada
This paper reviews emerging commercial pretreatment options that are available at wastewater treatment plants to enhance biogas (methane) generation from anaerobic digestion. Three pretreatment options are described and issues associated with implementation are discussed. The paper focuses on high-powered ultrasonication; chemical and pressure disruption; (Micro sludge) and combined thermal and pressure pretreatment (SUBBOR). Other more experimental pretreatment technologies such as electro pulse and microwave irradiation are not addressed as they have not yet been commercialized. Estimates of the increase in biogas generation that may be achieved with each option are presented. Comparison of power requirements is also presented where available. The results of site assessments at pilot and demonstration plants are presented. This paper does not address issues such as modifications that can be made to wastewater treatment processes (enhanced primary settling), sludge handling systems (thickening), or anaerobic digester design (Anglo American pancake, egg shape digester). Additionally, other operational factors that can influence existing digesters performance (enhanced mixing, submerged combustion, series operation, sludge recycling, thermophilic operation) as well as implementation of advanced digestion technologies temperature phase anaerobic digestion (TPAD), 2-Phase anaerobic digestion (AD), extended thermophilic anaerobic digestion (ETAD), Dual Digestion) are not discussed. Since there is considerable flexibility in the configuration and operation of sludge treatment processes at wastewater treatment plants the implementation of the various pretreatment options is somewhat site specific and should be evaluated on a case by case basis.
Key words: Sludge, Biosolids, Pretreatment, Anaerobic Digestion, Biogas, Ultrasound, Microsludge, Sonico, SUBBOR
Role of Anaerobic Treatment Technology in Minimizing Waste Sludge Production in Sewage Treatment Plants
Henri Spanjers, Adriaan Mels, and Jules van Lier
Lettinga Associates Foundation, P.O. Box 500, NL-6700 AM Wageningen, The Netherlands
Grietje Zeeman and Gatze Lettinga
Department of Environmental Technology, Wageningen University, P.O. Box 8129, NL-6700 EV Wageningen, The Netherlands
This paper reviews the implementation of anaerobic sewage (pre-) treatment technology in combination with other pre-treatment technologies to substantially reduce waste sludge production. Two options are considered: 1) the application of Upflow Anaerobic Sludge Bed (UASB), Anaerobic Filter (AF), and/or hybrid UASB-AF process as an alternative to aerobic activated sludge systems, and 2) the enhanced primary sedimentation combined with proper primary sludge digestion. Based on available information of pilot plant and full-scale experiences with single-step conventional UASB treatment systems, it can be concluded that significant reduction in the volume of wet waste sludge can be achieved. Experimental results indicate that primary sedimentation of sewage can be significantly improved by using cationic polymer. Both the enhanced sedimentation process and the AF removed relatively more of inert particulate COD than biodegradable COD. Both the enhanced sedimentation process and the AF removed relatively more of inert particulate COD (chemical oxygen demand) than biodegradable COD. The two treatment methods produced sludge with similar anaerobic biodegradabilities, but the degradation of AF sludge proceeded faster.
Key words: Anaerobic filter, anaerobic treatment, waste sludge reduction, pre-treatment, UASB
Solid Waste Management at Municipal Sewerage Company in Budapest
Municipal Sewerage Company Ltd., Asztalos S.u.4. Budapest, 1087 Hungary
Solid waste management deals with not only the sludge, but with other residues of the sewerage and wastewater treatment: deposit of sewers, screen waste, decanted oil and grease, and settling of sand traps. The solid waste management means not only the disposal of the wastes, but also the treatment, minimization, and utilization of the wastes. The National Waste Management Law is only a few years old in Hungary. This paper provides information on four wastewater treatment plants in Budapest. It provides details of the current operations. However, as the legal system in Hungry is in transition, the paper discusses the needed evolution to full compliance with legal requirements. In addition, the paper addresses practical issues including economics of treatment operations.
Key words: solid waste management, sludge, screen waste, sand-trap settling, deposit of sewers, screen waste washing, sand washing, digestion, composting, drying, incineration, and land-filling
Review of Treatment Processes, Current Disposal Practices, and Quality Of Sewage Sludge Produced by Major Wastewater Treatment Plants in Syria
Marwan Dimashki,* Zakaria Al-Assali, and Daed Naser
Environmental Research Laboratory, The Higher Institute of Applied Sciences
& Technology, Damascus, P.O.Box 31983, SYRIA
Sewage sludge is rich in organic materials and nutrients that are necessary for the soil and plants. However, sludge produced by municipal wastewater treatment plants (WWTP) may contain heavy metals, and if present above certain levels, will limit sludge applications on land. Sludge generated by Damascus and Homs wastewater treatment plants were examined by several national analytical laboratories for their contents of heavy metals (i.e., Zn, Cu, Cd, Cr, Pb, Ni, Hg, Se, and As). Concentrations of heavy metals were found to be within the national and international standards for the application of sewage sludge on lands and for the utilization of sludge as a soil enhancer. In order to control the safe handling and utilization of produced sewage sludge in Syria, the responsible authorities have recently issued the necessary national standards and regulations.
Key words: Sewage sludge, sludge disposal, municipal wastewater treatment, soil conditioner, heavy metals
*Current address: UNDP-Syria, E-mail: email@example.com
Matrix-Filter System for Algae and Phosphorous Removal
Department of Civil Engineering, The University of Balamand, P.O.Box
100, North Lebanon
This paper summarizes the results of extensive laboratory experiments conducted for the determination of the effectiveness of a matrix-fill filter in removing algae and phosphorus during tertiary treatment. Filtration with this system has resulted in effluent of the required quality, low phosphorus and algae effluent and turbidity, with long filter runs in all modes of treatment and without the need for an excessive head of water. The system is economically viable, easy to operate, and suited more to rural areas for small and medium sized communities.
Key words: Algae, alum, filtration, phosphorus, polyelectrolytes, matrix-fill-filter, suspended solids, turbidity, tertiary wastewater treatment
Biosolids: A Promising Option for Sewage Sludge Utilization
Syed E. Hasan
Center for Applied Environmental Research, Department of Geosciences,
University of Missouri, Kansas City, MO 64110-2499, U.S.A.
This paper describes the difference between sewage sludge and biosolids. It relies upon regulations, standards and guides developed by the U. S. Environmental Protection Agency to identify requirements including limits for various contaminants in biosolids. The paper uses the example of a project performed in Poland to demonstrate the application of biosolids in remediation of heavily contaminated sites.
Land Application of Biosolids as an Environmentally Sound Technology for Wastewater Sludge
United Nations Environment Programme, Regional Office for West Asia, P.O. Box 10880, Manama, Bahrain
Biosolids consist of treated domestic wastewater sludge that meets standards
for utilizing as a plant fertilizer or soil conditioner. Biosolids standards
contain limitations for metal and other substances, pathogens, vector requirements
and best management practices. Applying biosolids to land exploits the
available nitrogen, phosphorus and potash as fertilizer for growing crops.
This controlled method is an environmentally sound practice. This paper
will address the integrative prerequisites of land application as an environmentally
sound technology, involving the physical, chemical and biological quality
of biosolids in light of agricultural land and crops' needs and conditions.
* Application methods including spray, injection, and mixing as well as consideration and timing of applications (climate and season relevance).
* Pollutants content guideline limits (maximum ceiling concentrations and quantities) and loading control (annual and cumulative loading rates).
* Pathogen reduction and vector attraction decrease requirements.
* Nutrients requirements and agronomic rates (supply versus uptake).
* Selection of suitable crops including agronomic needs, distinction between applications to edible crops, pastures, or recreational gardens or forests.
* Site Suitability such as soil and topography, surface- and ground-water conditions, and remoteness.
* Risk assessment and management.
This biosolids management method is particularly beneficial in our region known for its arid climate, water scarcity, barren landscapes and desertification threats.
Assessment of Dewatering Sludge and Utilization
Environmental Sciences Department, Kuwait Institute for Scientific Research,
P.O.Box 244885,13109-Safat, State of Kuwait
Levels of trace metals were determined in dry sludge produced by two experimental dewatering units (belt filter and centrifuge) at the Jahra treatment plant. The plant is located 15 km west of Kuwait City and serves the Jahra City. The plant has been in operation since 1981 as a tertiary treatment plant and designed to receive daily 66,000m3/d of sewage. Over the 12 months study period, levels of heavy metals (in dry solid) at the pilot plant study showed: 124mg/kg of Cd, 33 mg/kg of Cr, 2 mg/kg of Co, 291mg/kg of Cu, 6485 mg/kg of Fe, 89 mg/kg of Mn, 24 mg/kg of Mo, 33 mg/kg of Ni, 81 mg/kg of Pb, 30 mg/kg of Sn, 10 mg/kg of V, and 738 mg/kg of Zn for belt filter unit. However for centrifuge unit the results were: 73 mg/kg of Cd, 71 mg/kg of Cr, 7 mg/kg of Co, 298 mg/kg of Cu, 10657 mg/kg of Fe, 154 mg/kg of Mn, 29 mg/kg of Mo, 91 mg/kg of Ni, 214 mg/kg of Pb, 31 mg/kg of Sn, 15 mg/kg of V and 441 mg/kg of Zn. These levels were generally below concentrations reported by the Kuwait Environment Public Authority, in the United States, and in United Kingdom. They were below the suggested concentrations limits for application of dry sludge on land. Results of the tests are encouraging to use the dry sludge for land application. For Kuwait, the feasibility for application of dry sludge was evaluated under local conditions in this study.
Key words: dry sludge, heavy metals, land application, sewage.
Suitability of Sewage Sludge to be Used as Manure for Green Leafy Plant; Parsley - A Case Study
Tamama H. A. Abdullah, Nadia H. S. Al-Baqsami and Mamta Tomar
Environmental Affairs Department, Ministry of Public Works, Kuwait
In Kuwait there are four wastewater treatment plants in operation namely
Ardiya, Jahra, Riqqa and Om Al-Hayman equipped with anaerobic, bed drying
and aerobic sludge treatment facilities respectively. Usually industrial
wastes are not mixed with municipal sewage; therefore sludge contains low
levels of inorganic and organic pollutants along with biological life.
The present study deals with the assessment of the quality of sewage sludge
produced at Jahra and Riqqa Wastewater Treatment Plants and its suitability
to be used as manure according to regulations set up by Environmental Protection
Authority, Kuwait. This paper reports the results of two phases of a three-phase
project. The three phases are as follows:
Phase I - Assessment of quality of sewage sludge including analysis of physico-chemical and microbiological parameters.
Phase II - Effect of sewage sludge on the quality of soil where parsley would be grown
Phase III - Effect of toxic and pathogenic quality of sewage sludge on the growth and quality of parsley plants and their suitability for human consumption. This phase will commence in the future.
Management of Waste at the Shuaiba Industrial Area
Department of Environmental Sciences, Kuwait Institute for Scientific
Research, Safat 13109, State of Kuwait
The Shuaiba Industrial Area (SIA) is considered to be the site holding most of the large-scale industries in Kuwait. It accommodates petrochemical and non-petrochemical companies. Two types of wastes produced have received the greatest attention: inert and hazardous wastes. Although, inert waste constitutes a large volume of waste generated in SIA, hazardous waste has been given the greater attention. Thus, the SIA Authority has recently established new regulations for waste disposal. The most stringent regulations are applied to hazardous wastes. This paper presents the categories of the waste materials generated in the SIA. Treatment and reuse technologies are also described and presented. This paper also summarizes the steps have been taken by SIA Authority to handle the wastes through the Shuaiba Solid Waste Reception Station facility where it is disposed of safely.
Key words: Hazardous; industry; non-hazardous; pollution; prevention; reuse; SIA; waste
Aerobic Waste Sewage Sludge Biotreatment for Enhanced Environmental Safety
Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait
Marc A. Deshusses
Chemical and Environmental Engineering, College of Engineering, University of California, Riverside, CA 92521, USA
Biofocus Foundation, London, EC4Y 0DD, Great Britain
Waste sewage sludge, an inevitable by-product of municipal sewage biotreatment, is a noxious and potentially hazardous slurry which needs effective treatment prior to its recycling to the natural environment as a soil conditioning agent. The most hazardous components in untreated waste sewage sludge are pathogens and toxic chemical residues. The major problems affecting guaranteed irreversible inactivation of pathogenic agents are a failure to fully understand the mechanisms responsible for cell death and how enhanced cell death can be affected by sludge bioprocess operating conditions. In these contexts, the efficacies of thermophilic aerobic, thermophilic anaerobic and mesophilic anaerobic sludge biotreatment processes are discussed in this review paper. In order to achieve both effective and economic biotreatment performance, a combination of thermophilic aerobic pre-treatment for hygienization and mesophilic anaerobic treatment for stabilization is recommended.
Key words: Sewage sludge, pathogens, thermophilic aerobic hygienization,
mesophilic anaerobic stabilization