Special Issue "Science and Technology of Wastewater and Sludge Treatment"

Guest Editor
Prof. Dr. Yung-Tse Hung
Department of Civil & Environmental Engineering, Cleveland State University, Stilwell Hall, 1960 East 24th Street, Cleveland, Ohio 44115, USA
Website: http://facultyprofile.csuohio.edu/csufacultyprofile/detail.cfm?FacultyID=Y_HUNG
E-Mail: y.hung@csuohio.edu
Fax: +1 216 6872596
Interests: water supply and water treatment; municipal wastewater treatment; industrial waste treatment; hazardous waste treatment; biological waste treatment; water pollution control

Dear Colleagues,

Wastewater comprises liquid waste discharged by domestic residences, commercial properties, industry, and/or agriculture and can encompass a wide range of potential contaminants and concentrations. Sludge refers to the residual, semi-solid material left from drinking water treatment, industrial wastewater, or sewage treatment processes. Pollutants generated from wastewater and sludge may cause adverse effect on the environment.  If not dealt properly they can cause pollution to surface and ground waters, create health problems and effect the environment.  Therefore, we would like to call for papers to disseminate and share findings on wastewater and sludge related research in addressing the problem scientifically.

Papers are selected by a rigorous peer review procedure with the aim of rapid and wide dissemination of research results, development and application.

Original research paper or reviews are invited in the following and related areas:

• Characterization and treatment processes for wastewater, biosolids and sludge
• Wastewater ,biosolids, and sludge management including their quality, planning, standards, regulations, policy, monitoring and the analysis
• Water pollution control
• The application of mathematical and modeling techniques in wastewater, biosolids, and sludge related research
• Economic and social aspects of wastewater, biosolids, and sludge management
• Case study on wastewater, biosolids,  and sludge treatment
• Wastewater reuse and sludge processing/recycling technology
• Risk assessment and management related to wastewater, biosolids, and sludge
• Ultimate disposal of biosolids and sludge
• Waste minimization and life cycle assessment
• Industrial waste treatment
• Hazardous waste treatment
• Radioactive waste pollution and treatment
• Other related research

Prof. Dr. Yung-Tse Hung
Prof. Dr. Hamidi Abdul Aziz
Prof. Dr. Khim Chu
Dr. Hana Salman
Dr. Puangrat Kajitvichyanukul
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

• wastewater and waste treatment
• sludge treatment and disposal
• niosolids treatment
• wastewater and waste management
• wastewater reuse
• sludge management
• industrial waste treatment
• hazardous waste treatment
• radioactive waste treatment
• water pollution control

Type of Paper: Article
Title: Sustainable and Innovative Solutions for Sewage Sludge Management
Author: Ludovico Spinosa
Affiliation: Govt. Commissariat for Environmental Emergency in Apulia Region, Bari, Italy; E-Mail: ludovico.spinosa@fastwebnet.it
Abstract: The management of sludge produced by municipal wastewater treatment plants is one of the  most difficult problem to be tackled and solved in both industrialised and developing countries, and possibly the most critical environmental issue to be undertaken, because sludge produced by wastewater treatment plants amounts to only a few percent by volume of the processed wastewater, but its handling accounts for up to 50% of total operating costs. The need to achieve a sustainable sludge management strategy is, therefore, become of greater concern, also because the conventional and more traditional recycling options, like direct utilisation in agriculture and other land uses, are progressively restricted, and also in some cases banned, by legislation, so the development of innovative systems to maximize recovery of useful materials and/or energy in a sustainable way has become necessary. As discussed by Spinosa (2010), the “sustainability” concept is today widely used when speaking of the development of human activities, especially in the environmental field, including sludge management. According to the original definition of 1987 by the United Nations, which defined sustainable developments as those that “meet present needs without compromising the ability of future generations to meet their needs”, sustainability is related to the quality of life in a community thus providing a healthy, productive, meaningful life for all community residents, in the present and the future. In practice “sustainability” occurs when natural or renewable resources are consumed less than, or at least equal to, nature’s ability to replenish them. For achieving effective sustainability, three elements, that are strongly interconnected to one another and cannot be considered separately, are of fundamental importance:

• the environmental element (environmentally robust, and supported by consistent and applicable normative and legal requirements);
• the economic element (economically affordable, technologically feasible, operationally viable);
• the social element (socially desirable, culturally acceptable, psychologically nurturing).

At present, sludge management systems are often inefficient and unsustainable, mainly because no single process or treatment, when used alone, is able by itself to address all three aspects, i.e. environmental, economic and social, which are needed to get an entirely sustainable system.
Therefore, a change toward more sustainable procedures must be promoted through an integrated approach, including the:

• better use of current technologies;
• innovative and new planning procedures;
• development of self-sustaining energy systems, or systems with a low energy impact;
• maximization of the production of materials, to be usefully reused for different purposes;
• better adaptation to the local specific context and situations.

This means that the development of sustainable sludge management procedures should at present require:

• the assessment of management routes capable of reducing the amount of sludge to be disposed of, and maximizing the recycle/recovery benefits;
• the development of operational systems appropriate to local circumstances, including economy, geography, climate, etc.
• the evaluation of the overall energy balance and costs of the entire processing sequence, including the wastewater treatment stage and the final sludge utilisation/disposal operation.

Strategies for reducing sludge mass/volume include, among others, methods specifically reducing sludge volumes by removing water, e.g thickening, dewatering and drying, and incineration, gasification, and other combined processes, while possibilities for material recovery include production of organic matter, nutrients, carbon source, coagulant, bricks, pumice, slag, artificial lightweight aggregate and Portland cement. The “nutrients” content of sludge is of interest, especially for phosphorus which has to be regarded as the most valuable product in the sludge, as it is not an endless natural resource. As far as possible energy recovery from sludge is concerned, several alternatives are available, from anaerobic digestion, to thermal processing technologies, including pyrolysis and gasification, whose advantages include reduction of volume and weight of waste, destruction of pathogenic and toxic organic compounds, and recovery of energy. Based on above considerations, an integrated system has been developed and discussed in this paper. The system includes three main processes/operations, i.e. Anaerobic digestion, Dewatering and Drying, and Thermal treatment by Pyrolysis/Gasification, which are efficiently coupled for the recovery of products for material reuse, and/or for energy purposes, in the specific context in which it is located. In particular, the enhancement of anaerobic digestion efficiency will reduce the amount of sludge to be disposed of, increase the digestion rate, and consequently the biogas production, and also improve sludge biological stabilisation. Anaerobic digestion will possibly allow phosphorus to be recovered. However, P recovery options have not yet been fully assessed and compared for practical application regarding their technical and economical feasibility and their environmental sustainability. The enhancement of sludge mechanical dewatering and drying efficiency will improve sludge physical consistency, and subsequent dried sludge utilisation together with treatment of drying off-gases. In addition, recovery of nitrogen from reject waters from sludge dewatering will be possible if it can provide an easily marketable product at a lower net cost than that needed for removal. Recovery options should be better defined and compared with innovative autotrophic biological removal processes, requiring low energy and maximizing nitrogen conversion efficiency, according to specific local conditions, ammonia nitrogen concentration in reject waters and marketability of recovered fertilizers. The enhancement of pyrolysis/gasification processes, through more efficient dewatering and drying previous processing, will improve production and quality of deriving products for material and/or energy utilisation, including construction or other useful carbonaceous materials and recovery of phosphorus via incinerated ash. Ash can be used as such as a substitute for P-Rock by the fertilizer industry or P–producing industry. However, phosphate can also be recovered from the ash by means of a wet-chemical process. In both cases it can be necessary to remove selectively the heavy metals from the ashes. Criteria for evaluating the overall energy balance and Life Cycle Assessment are also discussed. This integrated system makes possible to preferentially produce one or more material with respect to others depending on the specific local situation, thus fulfilling the environmental, the economic, and the social elements required by effective sustainability. The adaptability to local situations make this system very useful for developing countries.
Keywords: innovation; management; sewage sludge; sustainability; treatment