news details |
|
|
| Sustainability of Landfills | | | Dr. Manzoor Ahmad Yetoo | 10/18/2014 9:51:08 PM |
|
Sustainable landfilling is a
key-issue in modern waste
management concepts. However, no internationally accepted definition has been identified to date. The concept can, however, be understood as a landfill where the waste mass is already in a stable state, meaning the remaining turnover processes are low and emission release is below the local environmentally acceptable level. Or that it can be controlled by simple and natural measures, such as methane oxidation in landfill covers. Most of the remaining carbon and nitrogen is bonded in stable substances and the landfill can be regarded as a long-term carbon storage pool. In order to evaluate, assess and quantify these processes and pools, new methodologies and analytical tools are needed.
Sustainability in the context of landfilling often means a multi-barrier concept that includes the appropriate geological background, technical landfill equipment and pre-treatment technologies of waste prior to landfilling. When physical barriers fail due to aging, emission release should be below the environmentally acceptable level. This is particularly crucial when considering the standard use in Europe of insulating landfills by means of impermeable liners. Insulation interrupts all landfill processes, but liners will only hold over a limited period, and will inevitably fail at some (unknown) point in future.
The way to put the principle of sustainable landfilling into practice represents one of the main research issues for the scientific community. Several promising pre-treatment, in-situ treatment, and post-treatment measures and technologies are currently undergoing development to achieve a sustainable landfill concept with acceptable aftercare phases of about one generation. The latter aim is most likely to be achieved by modern landfills receiving pre-treated and separated waste streams. Moreover, promising technologies, such as in-situ aeration or flushing technologies, to enhance landfill processes and shorten aftercare periods of old, closed MSW landfills are available.
For a landfill to be considered sustainable, greenhouse gas emissions must be avoided. For mitigating methane emissions biocover systems can be applied. By providing optimum conditions for microbial methane oxidation and efficiently routing landfill gas to where these processes are enhanced, a number of bio-based systems, like interim or long-term biocovers, passively or actively vented biofilters, biowindows and daily-used biotarps, have been developed. These bio-based systems can be used in various configurations, including gas collection to capture fugitive emissions or alone during new landfill start-up.
Tools to evaluate the solid waste mass
During the last decade analytical tools such as Fourier transform infrared (FTIR) spectroscopy and thermal analysis have gained importance in the field of waste analytics. These methods are used in many industrial areas for process and quality control and are proven to be appropriate tools for waste characterisation.
Most of the remaining carbon (and nitrogen) is bonded in stable substances and the landfill can be regarded as a long-term carbon storage pool
Both methods characterise the whole sample by many data points and therefore provide comprehensive information on the material, its composition, properties and behaviour. The stage of degradation and the related reactivity/stability of waste organic matter are the focus of interest.
Depending on the questions to be answered corresponding models have already been developed. This is a prerequisite for practical application as they perform the transformation of the complex spectral or thermal pattern into readily comprehensible information. Changes in the chemical composition are evident. Based on the intensity of specific bands that are assigned to organic functional groups and their decrease with progressing mineralisation, an assessment of the waste stability is possible. The development of prediction models provides several advantages such as the avoidance of chemical analyses, minimisation of failures and cost-efficiency. Monitoring and assessment of both active and abandoned landfills with regard to stability and compliance are the main fields of application.
Leachate characterisation
Apart from solid waste characterisation, particular attention should be paid to leachate quality, primarily focusing on nitrogen compounds, which significantly influence the duration of the aftercare phase, and the required effort for leachate treatment. In contrast to solid waste samples taken from the landfill, which often represent only a snapshot in spatial distribution, leachate represents a sum-parameter reflecting the status-quo of an entire landfill, or landfill section.
Investigation of leachate using FTIR-spectroscopy provides an additional approach to assess sustainability. Various metabolic processes towards mineralisation occur in the solid waste material in landfills, which are reflected by changes in the chemical composition of the solid waste, and consequently by alteration of leachate characteristics.
Cover, gas emissions and methane oxidation
The vegetation ecology present at a landfill can give quick and comparatively cheap information. The base of this method is the fact that plant species differ in their claims for water and nutrients, and in their response on stresses such as higher salinity or oxygen limitations. These effects cause a physiological amplitude for each species.
Due to their composition and structure, landfill surfaces differ from the natural environment. Exploration of the landfill is based on bio-indication. Plants expose and visualise many factors and conditions over a longer period of time and shed light on the habitat's features by particular species and their succession, frequency, and diverse indicator properties. Evaluation of surface characteristics with respect to vegetation is performed by multivariate data analysis.
The author is an expert in environment ,project & waste Management, occupational safety & health & pollution control and empanelled expert for IRCA).
(You may reach him at [email protected])
|
|
|
|
|
|
|
|
|
|
|
|
|
| |
| |
|
|
|
|
 |
|
|
|
|
STOCK UPDATE |
|
|
 |
| BSE
Sensex |
 |
| NSE
Nifty |
|
|
| |
CRICKET UPDATE |
|
|
|
|
| |
| |
|
|
| |
|
|
|
|
| |
|
|
|
|
|
|
|
|
|
|
|
|
|
