Current state of sludge production, management, treatment and disposal in China.

Large amount of sludge has been a great trouble and raised significant concerns in China. This paper reviewed the current situation of sludge production, management, treatment and disposal in China. Total sludge production in China had an average annual growth of 13% from 2007 to 2013, and 6.25 million tons dry solids was produced in 2013. Per Capita sludge production in China is lower than that in developed countries. However, sludge management is poor in China. Administrative agents of sludge are not in accordance with each other. Laws and regulations of sludge management are incomplete and sometimes unrealistic. As to sludge treatment and disposal, many technical routes have been applied in China. Thickening, conditioning, and dewatering are three most used treatment methods, while application ratios of stabilization and drying are low in China. More than 80% of sludge is disposed by improper dumping in China. Regarding proper disposal, sanitary landfill is the commonest, followed by land application, incineration and building materials. According to the overall situation of China, "thickening-anaerobic digestion-dewatering-land application" is the priority technical route of sludge treatment and disposal. Good changes, current challenges and future perspectives of this technical route in China were analyzed and discussed in details.

EU policy on sewage sludge utilization and perspectives on new approaches of sludge management.

This paper presents the current sewage sludge legislation in Europe and expected developments regarding the coming directives on the application of the "End-of-waste" criteria and on fertilizers. Discussion on sludge production and processing is also included. The Directive 86/278 has regulated the use in agriculture of residual sludge from domestic and urban wastewater. After 1986, this directive was transposed in the different member state legislation and currently the national limit values on heavy metals, some organic micropollutants and pathogens are placed in a rather wide range. This seems the inevitable consequence of different attitudes towards sludge management practices in the member states. The discussion by the European Joint Research Center (JRC) in Seville regarding application of end-of-waste criteria for compost and digestate has produced a final document (IPTS 2014) where sludge was excluded from the organic wastes admitted for producing an end-of-waste compost. Sludge processing in Europe seems addressed to different goals: sludge minimization, full stabilization and hygienization by thermal hydrolysis processes before anaerobic digestion, and on-site incineration by fluidized bed furnace. Thermophilic anaerobic digestion was applied with success on the Prague WWTP with a preliminary lysimeter centrifugation. Coming techniques, like wet oxidation and pyrolysis, are applied only on very few plants.

Scientific basis of dissolved organic carbon limitation for landfilling of municipal treatment sludge--is it attainable and justifiable?

This study evaluated the scientific and technical basis of the dissolved organic carbon (DOC) limitation imposed on municipal sludge for landfilling, mainly for assessing the attainability of the implemented numerical level. For this purpose, related conceptual framework was analyzed, covering related sewage characteristics, soluble microbial products generation, and substrate solubilization and leakage due to hydrolysis. Soluble COD footprint was experimentally established for a selected treatment plant, including all the key steps in the sequence of wastewater treatment and sludge handling. Observed results were compared with reported DOCs in other treatment configurations. None of the leakage tests performed or considered in the study could even come close to the prescribed limitation. All observed results reflected 10-20 fold higher DOC levels than the numerical limit of 800 mg/kg (80 mg/L), providing conclusive evidence that the DOC limitation imposed on municipal treatment sludge for landfilling is not attainable, and therefore not justifiable on the basis of currently available technology.

Integrated planning of rehabilitation strategies for sewers.

Building measures in sewer systems are increasingly driven by rehabilitation/retrofitting and adaptation needs. Aging infrastructure together with changing boundary conditions (due to climate change, land-use change, demographic change) and also changing design standards and legislation require a prospective design to preserve the functionality of urban drainage systems not only today, but also in a long-term perspective. To improve a prospective design of urban water infrastructure, the Austrian Research Promotion Agency funded the research project 'REHAB - Integrated planning of rehabilitation strategies of urban infrastructure systems'. Therein a novel strategic planning tool which considers these external drivers of rehabilitation strategies is developed. In this study the scope of the project is described and, as well as first results regarding sewer pipe conditions, future development and vulnerability assessment are also discussed.

Guidelines and legislation for dye house effluents.

Increasing attention has been paid over the years to the environmental problems related to industrial activities. Environmental standards have been established and control organisms have been created with a view to applying restrictive legislation. In the dyeing industry, ennoblers discharge in the environment large volumes of strongly coloured effluents that are heavily loaded with pollutants and highly concentrated in salts. This chemical load is generated during the different steps of textile preparation. After reviewing the characteristics of these effluents, this paper gives a comparative review of the current legislations on the dyeing industry emissions. It examines more closely the discharge legislation, first in France and then in other countries around the world. A comparison of the six most representative parameters shows how different the applied constraints are in different countries.

Municipal sludge management and disposal in South Korea: status and a new sustainable approach.

Based on figures from 2002, 5216 ton/d of the municipal sludge is produced from 184 large municipal wastewater treatment plants in 111 cities with total treatment capacity of 19,229,745 m3/d. Even though the large amount of sludge disposal has depended greatly on ocean disposal and landfills until recently, the fraction of sludge reuse has gradually increased from 2.7% to 7%, since 1991. Due to a need of resources recovery from the sludge, high cost requirement of incineration and legislative regulation, recent new research is mainly focused on resources recovery and its reuse from the municipal sludge, such as high performance acid fermenter with pathogen reduction, crystallization (struvite and hydroxyapatite) using waste lime, cofermentation of municipal sludge with food waste, aerobic composting with P crystallization, vermistabilization, lime treatment, etc. Current research and practical activities with some efforts for the new technical development as well as environmental law and regulation are reviewed.

Contaminants in sludge: implications for management policies and land application.

Policies on sludge (or biosolids) management vary widely, particularly when decisions must be made on what to do with the final product. This paper examines the two principal rationales with which such decisions are made, and through which scientific knowledge is included in the process. These rationales are risk analysis (risk assessment and management), and the criterion of sustainability. Both are found to be potentially arbitrary due to the difficulty in defining the individual constituents necessary to relate environmental phenomena to environmental policy. To place the difficulties in a practical context, this paper presents research results from three recent projects concerned with contaminants in sludge (phosphorus, flocculant polymers, and polymer-surfactant aggregates), and uses the findings to exemplify the dilemma encountered in policy making. A path forward is proposed.

Sustainable biosolids--welcomed practice through community partnership and the consequential economic benefits.

Technically, most people agree that conserving soil organic matter and completing nutrient cycles by applying animal manures, treated organic wastes and biosolids to land is the most sustainable option in the majority of situations. It is also generally the least expensive. There has been a huge amount of research into the hazards, and this has concluded that the risks can be managed to acceptable levels. But there has been insufficient attention to communicating this knowledge, as so often in the scientific and technological arena. Perception is reality. Nowadays compliance with regulations (whilst essential) is not enough; public and stakeholder attitudes can be of decisive importance. Sometimes policy-makers speculate what public attitudes might be without really asking them. This paper will describe an initiative to create a partnership open to anybody with an interest in the use of organic materials on land to develop consensus on good practice and to share knowledge. It summarises an attitude survey of more than 140 organisations, which was then debated at a workshop in July 2002. The conclusion from this study was that all parties considered a partnership is essential to share knowledge, build mutual trust and agree practices that are welcomed by all in the food chain. The paper will describe the steps to establishing a partnership organisation, its aims and objectives, the work to date and the plans for the future. The Environment Agency considers this very important and has largely funded the work to date. The consequences of failing to establish welcomed practices would be loss of the facility to use organic resources on land.

Phosphorus restrictions for land application of biosolids: current status and future trends.

The application of biosolids (sewage sludge) to agricultural soils provides P in excess of crop needs when applied to meet the N needs of most agronomic crops. These overapplications can result in the buildup of P in soils to values well above those needed for optimum crop yields and also may increase risk of P losses to surface and ground waters. Because of concerns regarding the influence of P on water quality in the USA, many state and federal agencies now recommend or require P-based nutrient management plans for animal manures. Similar actions are now under consideration for the land application of biosolids. We reviewed the literature on this subject and conducted a national survey to determine if states had restrictions on P levels in biosolids-amended soils. The literature review indicates that while the current N-based approach to biosolids management does result in increases of soil P, some properties of biosolids may mitigate the environmental risk to water quality associated with land application of P in biosolids. Results of the survey showed that 24 states have regulations or guidelines that can be imposed to restrict land application of biosolids based on P. Many of these states use numerical thresholds for P in biosolids-amended soils that are based on soil test phosphorus (STP) values that are much greater than the values considered to be agronomically beneficial. We suggest there is the need for a comprehensive environmental risk assessment of biosolids P. If risk assessment suggests the need for regulation of biosolids application, we suggest regulations be based on the P Site Index (PSI), which is the method being used by most states for animal manure management.