Analysis of landfill gas migration by use of autonomous gas monitoring platforms

Autonomous gas sensing platforms have been developed to facilitate the long-term continuous monitoring of landfill gas concentrations. The analysis of a municipal landfill site in Ireland forms part of an on-going collaboration with the Environmental Protection Agency in monitoring the migration of greenhouse gases, i.e. methane and carbon dioxide, emanating from the landfill site. Target gas concentrations were automatically recorded via infrared gas sensors calibrated for the respective gases, with this data being logged remotely every six hours to a central base-station. The autonomous platform with its web-based portal interface provides a flexible alternative to the existing labor-intensive, manual monitoring routines. Frequent occurrences of 70% v/v methane and 6% v/v carbon dioxide were substantially in breach of the regulatory limits of 1.5% v/v and 1.0% v/v, respectively. These excessive levels of gas migration were analyzed with respect to SCADA flare data, on-site measurements and meteorological data

Measurement of representative landfill gas migration samples at landfill perimeters: a case study

This paper describes the development of a fully integrated autonomous system based on existing infrared sensing technology capable of monitoring landfill gas migration (specifically carbon dioxide and methane) at landfill sites. Sampling using the described system was validated against the industry standard, GA2000 Plus hand held device, manufactured by Geotechnical Instruments Inc. As a consequence of repeated sampling during validation experiments, fluctuations in the gas mixtures became apparent. This initiated a parallel study into what constitutes a representative sample of landfill gas migration as reported to the Environmental Protection Agency. The work described in this paper shows that gas mixture concentrations change with depth of extraction from the borehole well, but with evidence of a steady state after a time

Wearable gas sensors

Wearable sensing applications have attracted much attention in recent years. The aim of the FP6 funded Proetex project is improving safety and efficiency of emergency personnel by developing integrated wearable sensor systems. This paper describes recent developments in the integration of sensing platforms into wearables for the continuous monitoring of environmentally harmful gases surrounding emergency personnel. Low-power miniature CO and CO2 sensors have been successfully integrated in a jacket collar and boot worn by emergency personnel. These sensors need to provide information about the level of gas in the surrounding environment without obstructing the activities of the wearer. This has been achieved by integrating special pockets on the jacket and boot of fire-fighters. Each sensor is attached to a sensing module for signal accommodation and data transfer. The sensor performance has been evaluated by simulation of real-life situations. These wearable gas sensors will dramatically improve personnel awareness of potential hazard and can function as a personal warning system. In this way, fire-fighter’s jacket and boot not only protect the wearer, but have a second function of providing valuable information on external hazards. The authors gratefully acknowledge the financial support of the Science Foundation Ireland (07/CE/I1147) and the EU project FP6-2004-IST-4-026987. We also acknowledge contribution of University of Pisa (Italy), Zarlink Semiconductor (UK), and Diadora/Invicta Group (Italy)

Monitoring of gas emissions at landfill sites using autonomous gas sensors

Executive Summary This report details the work carried out during the Smart Plant project (2005-AIC-MS-43-M4). As part of this research, an autonomous platform for monitoring greenhouse gases (methane (CH4), carbon dioxide (CO2)) has been developed, prototyped and field validated. The modular design employed means that the platform can be readily adapted for a variety of applications involving these and other target gases such as hydrogen sulfide (H2S), ammonia (NH3) and carbon monoxide (CO) and the authors are in the process of completing several short demonstrator projects to illustrate the potential of the platform for some of these applications. The field validation for the greenhouse gas monitoring platform was carried out at two landfill sites in Ireland. The unit was used to monitor the concentration of CO2 and CH4 gas at perimeter borehole wells. The final prototype was deployed for over 4 months and successfully extracted samples from the assigned perimeter borehole well headspace, measured them and sent the data to a database via a global system for mobile (GSM) communications. The data were represented via an updating graph in a web interface. Sampling was carried out twice per day, giving a 60-fold increase on current monitoring procedures which provide one gas concentration measurement per month. From additional work described in this report, a number of conclusions were drawn regarding lateral landfill gas migration on a landfill site and the management of this migration to the site’s perimeter. To provide frequent, reliable monitoring of landfill gas migration to perimeter borehole wells, the unit needs to: • Be fully autonomous; • Be capable of extracting a gas sample from a borehole well independently of personnel; • Be able to relay the data in near real time to a base station; and • Have sensors with a range capable of adequately monitoring gas events accurately at all times. The authors believe that a unit capable of such monitoring has been developed and validated. This unit provides a powerful tool for effective management of landfill site gases. The effectiveness of this unit has been recognised by the site management team at the long-term deployment trial site, and the data gathered have been used to improve the day-to-day operations and gas management system on-site. The authors make the following recommendations: 1. The dynamics of the landfill gas management system cannot be captured by taking measurements once per month; thus, a minimum sampling rate of once per day is advised. 2. The sampling protocol should be changed: (i) Borehole well samples should not be taken from the top of the well but should be extracted at a depth within the headspace (0.5–1.0 m). The measurement depth will be dependent on the water table and headspace depth within the borehole well. (ii) The sampling time should be increased to 3 min to obtain a steady-state measurement from the headspace and to take a representative sample; and (iii) For continuous monitoring on-site, the extracted sample should be recycled back into the borehole well. However, for compliance monitoring, the sample should not be returned to the borehole well. 3. Devices should be placed at all borehole wells so the balance on the site can be maintained through the gas management system and extraction issues can be quickly recognised and addressed before there are events of high gas migration to the perimeter. 4. A pilot study should be carried out by the EPA using 10 of these autonomous devices over three to five sites to show the need and value for this type of sampling on Irish landfill sites

Landfill gas monitoring network - development of wireless sensor network platforms

A wireless sensor network has been developed for the application of landfill gas monitoring, specifically sensing methane, carbon dioxide and extraction pressure. This collaborative work with the Irish Environmental Protection Agency has been motivated by the need to reduce greenhouse gas emissions as well as aiming to improve landfill gas management and utilisation. This paper describes the preliminary findings of an ongoing trial deployment of multiple sensing platforms on an active landfill facility; data has been acquired for nine months to date. The platforms have operated successfully despite adverse on-site conditions, with validity demonstrated by reasonably strong correlation with independent on-site measurements. The increased temporal and spatial resolution provided by distributed sensor platforms is discussed with regard to improving landfill gas management practice

Distributed environmental monitoring

With increasingly ubiquitous use of web-based technologies in society today, autonomous sensor networks represent the future in large-scale information acquisition for applications ranging from environmental monitoring to in vivo sensing. This chapter presents a range of on-going projects with an emphasis on environmental sensing; relevant literature pertaining to sensor networks is reviewed, validated sensing applications are described and the contribution of high-resolution temporal data to better decision-making is discussed

Development of optical sensing system for detection of Fe ions using conductive polymer actuator based microfluidic pump

In this paper, we present a novel microfluidic optical sensing system by combining a low-power conductive polymer -based microfluidic pump and a microfluidic chip integrated with an optical sensor. A self priming microfluidic pump is developed using a polypyrrole. A microfluidic chip- optical detector module that contained an optical cuvette with LED and photo-diode optical sensing module was fabricated. Integration of the micro pump and the microfluidic chips complete the sensing system. The pump performance and its application in chemical analysis have been demonstrated in the detection of Fe ions

Wearable sensing application- carbon dioxide monitoring for emergency personnel using wearable sensors

The development of wearable sensing technologies is a great challenge which is being addressed by the Proetex FP6 project (www.proetex.org). Its main aim is the development of wearable sensors to improve the safety and efficiency of emergency personnel. This will be achieved by continuous, real-time monitoring of vital signs, posture, activity, and external hazards surrounding emergency workers. We report here the development of carbon dioxide (CO2) sensing boot by incorporating commercially available CO2 sensor with a wireless platform into the boot assembly. Carefully selected commercially available sensors have been tested. Some of the key characteristics of the selected sensors are high selectivity and sensitivity, robustness and the power demand. This paper discusses some of the results of CO2 sensor tests and sensor integration with wireless data transmission