'Green' treatment of acid mine drainage - a step towards sustainability

Sustainability is becoming increasingly important in the mining and mineral processing industries and must incorporate the associated waste products. Acid mine drainage (AMD) is one such by-product and is one of the most serious environmental problems facing the minerals industry today. The oxidation of sulphidic mine wastes often continues for a substantial period of time after mine closure, resulting in difficult and costly remediation and rehabilitation works. Mining companies are often reluctant to spend increasing amounts of money on waste treatment when the mine life is limited or even finished. Hence a simple, low maintenance and low-cost method of treating AMD is required. Whilst this paper does not address the issue of AMD, it does propose methods for removal of individual species from AMD with potential benefits, including raising AMD pH.

A novel concept of using biosolids as a biological adsorbent, or ‘biosorbent’, of metals from AMD is being investigated at a laboratory/pilot scale level. Biosolids are a by-product resulting from the biological treatment of wastewater, and have been previously shown to adsorb metals from aqueous solutions. This could lead to an environmentally sustainable or ‘green’ method for treating both AMD discharges and disposing/reusing the biosolids.

The result of a laboratory-scale study of the biosorption of Zn(II) is presented in this paper. Physical parameters including reaction kinetics, mixing speed and solution pH were investigated. Solution pH also rose an average of 2 pH units over the 24 hour equilibrium time – a valuable side effect when treating acid mine drainage. The outcome of the study highlights the usefulness of biosolids as a biosorbent for the removal/recovery of metal ions from acid mine drainage. A simple, low-cost treatment technology requiring low maintenance would be beneficial to the mining industry to address some issues relating to AMD and would help integrate environmental and economic considerations into sustainable environmental management.

Responding to terrorism through networks at sites of critical infrastructure : a case study of Australian airport security networks

The importance of effective multilateral security networks is widely recognised in Australia and internationally as being essential to facilitate the large-scale sharing of information required to respond to the threat of terrorism. Australian national security agencies are currently constructing networks in order to bring the diverse national and international security agencies together to achieve this. This paper examines this process of security network formation in the area of critical infrastructure protection, with particular emphasis on airport security. We address the key issues and factors shaping network formation and the dynamics involved in network practice. These include the need for the networks to extend membership beyond the strictly defined elements of national security; the integration of public and private ‘nodes’ in counter-terrorism ‘networks’; and the broader ‘responsibilisation’ of the private sector and the challenges with ‘enabling’ them in counter-terrorism networks. We argue that the need to integrate public and private agencies in counter-terrorism networks is necessary but faces considerable organisational, cultural, and legal barriers.

The normative distribution of chest tube drainage volume after coronary artery bypass grafting

Background
Little evidence exists to describe expected volumes of chest tube (CT) drainage after coronary artery bypass grafting (CABG).

Objectives
The study objective was to map the trajectory of CT drainage volumes from insertion to removal after CABG.

Design

This was a retrospective, descriptive study.
Patients
The study included 239 patients who underwent CABG at a single metropolitan hospital in Melbourne, Australia.

Results
The sample (N = 234), aged 68.7 years (standard deviation [SD] 9.9), was predominantly male (N = 185, 79.1%). The mean duration of CT insertion was 45.2 hours (SD 26.7), and total drainage volume was 1300.6 mL (SD 763.8). Drainage volumes plateau to 31 mL per hour, 8 hours after surgery. From 24 to 48 hours, the mean drainage was 21 mL per hour. Drainage volumes varied between genders.

Conclusions
Evidence of similar drainage patterns in other populations is difficult to locate. If the pattern of drainage shown in this study is consistent, experimental intervention studies comparing standard removal time and earlier removal are recommended. If not, prospective collection of relevant preoperative, intraoperative, and postoperative factors across multiple sites is necessary to determine which patient or practice variations influence CT drainage patterns after CABG.

Sudden drawdown and drainage of a horizontal aquifer

Drainage of a saturated horizontal aquifer following a sudden drawdown is reanalyzed using the Boussinesq equation. The effect of the finite length of the aquifer is considered in detail. An analytical approximation based on a superposition principle yields a very good estimate of the outflow when compared to accurate numerical solutions. An illustration of the new analytical approach to analyze basin-scale field data is used to demonstrate possible field applications of the new solution.

Simulation-based input loading condition optimisation of airport baggage handling systems

Scheduling check-in station operations are a challenging problem within airport systems. Prior to determining check-in resource schedules, an important step is to estimate the Baggage Handling System (BHS) operating capacity under non-stationary conditions. This ensures that check-in stations are not overloaded with bags, which would adversely affect the system and cause cascade stops and blockages. Cascading blockages can potentially lead to a poor level of service and in worst scenario a customer may depart without their bags. This paper presents an empirical study of a multiobjective problem within a BHS system. The goal is to estimate near optimal input operating conditions, such that no blockages occurs at check-in stations, while minimising the baggage travel time and maximising the throughput performance measures. We provide a practical hybrid simulation and binary search technique to determine a near optimal input throughput operating condition. The algorithm generates capacity constraint information that may be used by a scheduler to plan check-in operations based on flight arrival schedules.

Acid drainage, limnology and bioremediation of western Victorian coal mine lakes

Rehabilitation of Alcoa's Anglesea open cut brown coal mine to a healthy lake has many environmental challenges. The study of regional acid drainage, limnology of Wenslydale Coal Mine Lake and passive bioremediation of acid mine water has shown that a healthy lake can be created.

Timing and frequency data for passenger divesting at Melbourne domestic airport

The data covers the timing and frequency for divesting in the passenger screening process at Melbourne Airport, Victoria. Divesting is defined as the process of removing items from one's person before going through the screening process and placing them and cabin luggage onto the X-ray conveyor. This may also include removing items from bags to assist in the screening process.

Timing and frequency data for passenger divesting at Sydney domestic airport

The data covers the timing and frequency for divesting in the passenger screening process at Sydney Airport, New South Wales. Divesting is defined as the process of removing items from one's person before going through the screening process and placing them and cabin luggage onto the X-ray conveyor. This may also include removing items from bags to assist in the screening process.

Timing and frequency data for passenger divesting at Adelaide domestic airport

The data covers the timing and frequency for divesting in the passenger screening process at Adelaide Airport, South Australia. Divesting is defined as the process of removing items from one's person before going through the screening process and placing them and cabin luggage onto the X-ray conveyor. This may also include removing items from bags to assist in the screening process.

Timing and frequency data for passenger composing at Melbourne domestic airport

The data covers the timing and frequency for composing in the passenger screening process at Melbourne Airport, Victoria. Composing is defined as the process of collecting personal items after the screening process.

Timing and frequency data for passenger composing at Sydney domestic airport

The data covers the timing and frequency for composing in the passenger screening process at Sydney Airport, New South Wales. Composing is defined as the process of collecting personal items after the screening process.

Timing and frequency data for passenger composing at Adelaide domestic airport

The data covers the timing and frequency for composing in the passenger screening process at Adelaide Airport, South Australia. Composing is defined as the process of collecting personal items after the screening process.