ARTICLE

Ecotechnology at Southern Cross University - Australia

By Leigh Davison, Murray Cullen and Keith Bolton

Contact:

Dr Leigh Davison
Head of Centre for Ecotechnology
School of Environmental Science and Management
Southern Cross University
PO Box 157, Lismore, 2480,
Australia
http://ecotechnology.scu.edu.au/

Background

Much of eastern Australia has been in drought for a number of years, and there has been widespread questioning of traditional approaches to urban water cycle management. The somewhat related issues of nutrient and carbon cycle management are also starting to be looked at with fresh eyes in this country. This is particularly true in the rapidly developing 500 km strip of land on the country's east coast, between Coffs Harbor in the south (30^o S) and Hervey Bay in the north (25^o S). This coastal strip is predicted to contain 25% of Australia's population by 2030.

Southern Cross University (SCU) is located in the city of Lismore (28^o S, population 40,000) approximately 200 km south of Brisbane, in one of the major regional development nodes.

The Centre for Ecotechnology at SCU was established in response to increasing demand for research and consultancy services in a number of areas related to the conservation, recovery, and protection of resources and the natural environment that have arisen as a result of the current surge in human population.

Onsite wastewater management

Much of the early work conducted within the Centre was focused on issues related to onsite wastewater management. A number of composting toilet designs have been developed and refined and several studies have indicated that initial misgivings by regulators concerning health and amenity issues have been unfounded. There are currently over four hundred domestic composting toilets in the Lismore-Byron area and the popularity of the technology here confirms the hypothesis that innovations tend to take hold in local geographical areas and within particular sub-populations prior to spreading to the general population. Factors which have favored uptake of the composting toilet here include

• (a) the existence of a significant number of people who place environmental responsibility near the top of the list of priorities,
• (b) well-established formal and informal communication networks,
• (c) local health regulators with sufficient adaptability to try something new, and
• (d) the introduction of performance-based (rather than prescriptive) onsite wastewater management guidelines.

Another line of research and development related to onsite wastewater management has been in the field of horizontal subsurface flow wetlands (reed beds) for domestic wastewater treatment. After some early teething problems related to poor workmanship by installers who are unfamiliar with its design requirements, this technology is increasing in popularity here. Over 30 studies of reed bed performance by researchers in our Centre have led to the development of first order models that predict organic matter (BOD) and total nitrogen (TN) removal as a function of residence time. Figure 1 illustrates the performance predicted by these models. Total nitrogen removal has been particularly impressive. Because nitrogen is a pollutant of particular concern in this part of the world, the reed bed's popularity as a secondary treatment device is increasing.

Ongoing R&D is concerned with making reed beds easier to install. In this regard we are working with manufacturers to develop standard components. An interesting discovery related to reed bed sustainability has been the fact that we are finding earthworms colonizing the beds. We have been able to show that these creatures are removing clogging material from the gravel substrate surfaces and deposing it as worm castings on the surface.

Other work in the Centre has focused on the use of reed beds for the removal of nutrients from nursery runoff. In this type of effluent, TN concentrations can typically be reduced from 10 mg/L down to 0.4 mg/L with four days residence in a reed bed. Associated research here has shown that the inclusion of reed beds in the treatment train of closed loop plant nursery water cycles will lead to the removal of plant pathogens such as Phytophthera and Pythium with residence time as low as one day.

As the adaptability of the reed bed approach has become more widely known in our region, we have been involved in its application to other effluents. In a recent project, we conducted pilot scale trials and subsequently designed a landfill leachate treatment system based on a free water surface wetland and vertical flow wetland (VFW). Research into suitable materials for VFW and sand filter media is ongoing, and one project is examining the possibility of crushed glass for this purpose.

Waste minimization and education

Solid waste minimization projects within the Centre for Ecotechnology are concerned with the reduction of commercial and industrial material going to landfill. An innovative education program is being run in conjunction with Lismore City Council to develop waste reduction skills for local businesses. Murray Cullen, the Centre's coordinator for education and training, is also conducting training courses for landfill operators and conducting waste audits to identify areas of future waste reduction and recycling opportunities.

A new approach to centralized wastewater management

For the last three years Dr. Keith Bolton, Project manager with the Centre for Ecotechnology, has been directing a project at Byron Bay aimed at developing methods to simultaneously manage four major environmental problems.

The problems

Wetland degradation. Extensive paperbark wetlands were once the dominant feature around the low-lying areas in Byron Bay. However, almost all of these paperbark trees were cleared, and very few of the original trees remain.

Acid sulfate soils. Acid sulfate soils are naturally occurring and prevalent in the coastal regions of Australia and produce sulfuric acid when they are drained. A high level of drainage has occurred in Byron Bay, resulting in serious damage to the local waterways, culminating in regular fish kills and massive loss of biodiversity.

Increased effluent flows. Effluent flows from the West Byron Sewage Treatment Plant are increasing in response to a high rate of development

Greenhouse effect. The greenhouse effect is caused by the burning of fossil fuels, which release carbon dioxide into the atmosphere and warms up the Earth. A consequence is increased sea levels, which threatens the long-term sustainability of coastal towns and cities.

The solutions

Wetland restoration. More than half a million paperbark trees have been planted on a 24-hectare site next to the West Byron STP, joining several wetland fragments, improving the biodiversity and connectivity of the Belongil Catchment (Figure 2).

Effluent management: Effluent from the West Byron Sewage Treatment Plant is irrigated onto the regenerating wetland, providing water and some nutrients for their growth. The densely planted trees "pump-and-polish" effluent, transpiring excess water to the atmosphere and providing a high level of treatment for the effluent.

Acid sulfate soil management. Effluent is used to maintain the water tables above the acid sulfate soil layer, preventing its oxidation and the further formation of acid. In addition, effluent is alkaline, and its addition helps to buffer existing acid products.

Greenhouse effect. Paperbark wetlands remove carbon dioxide from the atmosphere and store carbon in an accumulating peat layer, which is more than 50% carbon! This represents a long-term carbon sink, which will eventually turn into coal, thus reversing the greenhouse effect.

The project has attracted much attention and is widely regarded as a showpiece of sustainability.

The Mop Crop Project

Another project being directed by Dr. Bolton is related to the use of high yielding plants to mop up nutrients in municipal wastewater. "Mop-crop" is a term referring to agricultural crops that sequester nutrients and transpire water from effluent. Mop-crops are grown in "sewage farms", which are situated on agricultural land irrigated with sewage effluent. Effluent comprises the two scarcest agricultural resources water and nutrients. Nutrients are removed during harvesting, enabling them to be recycled back to the terrestrial system. Furthermore, a wide array of soil-based physical, chemical, and biological processes transforms nutrients and other pollutants. Transpiration and evaporation removes water from the system, and runoff and percolation from well-designed reuse sites is of a high quality. The generation of marketable biomass offsets the high costs of wastewater treatment and increases the productivity of the local economy. Byron and Ballina Shire Councils are collaborating with Centre for Ecotechnology to examine the suitability of fiber species as mop-crops in the high rainfall environments. These include hemp (Cannabis sativa), kenaf (Hibiscus cannabinus) and 14 bamboo species. Figure 3 is a schematic representation of the experimental setup for one of the mop crop trials.

A research project to evaluate the use of "mop crop" organic material as a green waste source for vermicomposting is about to commence. This project will determine the inputs and outputs from vermicomposting and help to determine if such a process is commercially viable.

Undergraduate Course Unit in Ecotechnology at Southern Cross University

The Centre for Ecotechnology is situated within the School of Environmental Science and Management at SCU. This School runs a three-year Bachelor of Applied Science Degree with majors in Fisheries Management, Coastal Zone Management, Marine Science, and Environmental Resource Management. There is also a four-year undergraduate degree in Subtropical Forestry. Students in the three year degree courses are required to complete 24 course units. A full time student would typically accomplish this at the rate of four units per semester.

The recent surge in ecotechnological activity within the Centre has had benefits for both undergraduates and recent graduates of the School and up to 14 people are employed at any given time on projects associated with the Centre. These projects also provide many opportunities for undergraduate research activity. In addition, First Semester 2004 has seen the introduction of a course unit in Ecotechnology. Subject material for this third year unit is based on issues related to the task of creating human settlements with sustainable water, nutrient and carbon cycles. Students are presented with real world problems based on projects arising from the work being done by staff in these fields.

Most of the students doing Ecotechnology are majoring in the Environmental Resource Management stream, which has an emphasis on land and water management. They would typically be taking the unit in their 5^th semester of study and would have previously studied units in chemistry, biology, ecology, soils and water, waste management, etc., as well as having been introduced to computing and statistical methods. A major aim of the unit is to introduce these students, who have been working within a paradigm dominated by the "earth and life sciences", to the "engineering" approach. Case studies are taken from agricultural and domestic material flow situations. There is a strong emphasis on the use of spreadsheet modeling to perform analyses and mass balances. This is proving challenging for some of the less numerate students and some adjustments will be made in future to cater for their needs.