Performance evaluation of onsite sewage treatment : Evaluation of current research

Efficient management of domestic wastewater is a primary requirement for human well being. Failure to adequately address issues of wastewater collection, treatment and disposal can lead to adverse public health and environmental impacts. The increasing spread of urbanisation has led to the conversion of previously rural land into urban developments and the more intensive development of semi urban areas. However the provision of reticulated sewerage facilities has not kept pace with this expansion in urbanisation. This has resulted in a growing dependency on onsite sewage treatment. Though considered only as a temporary measure in the past, these systems are now considered as the most cost effective option and have become a permanent feature in some urban areas. This report is the first of a series of reports to be produced and is the outcome of a research project initiated by the Brisbane City Council. The primary objective of the research undertaken was to relate the treatment performance of onsite sewage treatment systems with soil conditions at site, with the emphasis being on septic tanks. This report consists of a ‘state of the art’ review of research undertaken in the arena of onsite sewage treatment. The evaluation of research brings together significant work undertaken locally and overseas. It focuses mainly on septic tanks in keeping with the primary objectives of the project. This report has acted as the springboard for the later field investigations and analysis undertaken as part of the project. Septic tanks still continue to be used widely due to their simplicity and low cost. Generally the treatment performance of septic tanks can be highly variable due to numerous factors, but a properly designed, operated and maintained septic tank can produce effluent of satisfactory quality. The reduction of hydraulic surges from washing machines and dishwashers, regular removal of accumulated septage and the elimination of harmful chemicals are some of the practices that can improve system performance considerably. The relative advantages of multi chamber over single chamber septic tanks is an issue that needs to be resolved in view of the conflicting research outcomes. In recent years, aerobic wastewater treatment systems (AWTS) have been gaining in popularity. This can be mainly attributed to the desire to avoid subsurface effluent disposal, which is the main cause of septic tank failure. The use of aerobic processes for treatment of wastewater and the disinfection of effluent prior to disposal is capable of producing effluent of a quality suitable for surface disposal. However the field performance of these has been disappointing. A significant number of these systems do not perform to stipulated standards and quality can be highly variable. This is primarily due to houseowner neglect or ignorance of correct operational and maintenance procedures. The other problems include greater susceptibility to shock loadings and sludge bulking. As identified in literature a number of design features can also contribute to this wide variation in quality. The other treatment processes in common use are the various types of filter systems. These include intermittent and recirculating sand filters. These systems too have their inherent advantages and disadvantages. Furthermore as in the case of aerobic systems, their performance is very much dependent on individual houseowner operation and maintenance practices. In recent years the use of biofilters has attracted research interest and particularly the use of peat. High removal rates of various wastewater pollutants have been reported in research literature. Despite these satisfactory results, leachate from peat has been reported in various studies. This is an issue that needs further investigations and as such biofilters can still be considered to be in the experimental stage. The use of other filter media such as absorbent plastic and bark has also been reported in literature. The safe and hygienic disposal of treated effluent is a matter of concern in the case of onsite sewage treatment. Subsurface disposal is the most common and the only option in the case of septic tank treatment. Soil is an excellent treatment medium if suitable conditions are present. The processes of sorption, filtration and oxidation can remove the various wastewater pollutants. The subsurface characteristics of the disposal area are among the most important parameters governing process performance. Therefore it is important that the soil and topographic conditions are taken into consideration in the design of the soil absorption system. Seepage trenches and beds are the common systems in use. Seepage pits or chambers can be used where subsurface conditions warrant, whilst above grade mounds have been recommended for a variety of difficult site conditions. All these systems have their inherent advantages and disadvantages and the preferable soil absorption system should be selected based on site characteristics. The use of gravel as in-fill for beds and trenches is open to question. It does not contribute to effluent treatment and has been shown to reduce the effective infiltrative surface area. This is due to physical obstruction and the migration of fines entrained in the gravel, into the soil matrix. The surface application of effluent is coming into increasing use with the advent of aerobic treatment systems. This has the advantage that treatment is undertaken on the upper soil horizons, which is chemically and biologically the most effective in effluent renovation. Numerous research studies have demonstrated the feasibility of this practice. However the overriding criteria is the quality of the effluent. It has to be of exceptionally good quality in order to ensure that there are no resulting public health impacts due to aerosol drift. This essentially is the main issue of concern, due to the unreliability of the effluent quality from aerobic systems. Secondly, it has also been found that most householders do not take adequate care in the operation of spray irrigation systems or in the maintenance of the irrigation area. Under these circumstances surface disposal of effluent should be approached with caution and would require appropriate householder education and stringent compliance requirements. However despite all this, the efficiency with which the process is undertaken will ultimately rest with the individual householder and this is where most concern rests. Greywater too should require similar considerations. Surface irrigation of greywater is currently being permitted in a number of local authority jurisdictions in Queensland. Considering the fact that greywater constitutes the largest fraction of the total wastewater generated in a household, it could be considered to be a potential resource. Unfortunately in most circumstances the only pretreatment that is required to be undertaken prior to reuse is the removal of oil and grease. This is an issue of concern as greywater can considered to be a weak to medium sewage as it contains primary pollutants such as BOD material and nutrients and may also include microbial contamination. Therefore its use for surface irrigation can pose a potential health risk. This is further compounded by the fact that most householders are unaware of the potential adverse impacts of indiscriminate greywater reuse. As in the case of blackwater effluent reuse, there have been suggestions that greywater should also be subjected to stringent guidelines. Under these circumstances the surface application of any wastewater requires careful consideration. The other option available for the disposal effluent is the use of evaporation systems. The use of evapotranspiration systems has been covered in this report. Research has shown that these systems are susceptible to a number of factors and in particular to climatic conditions. As such their applicability is location specific. Also the design of systems based solely on evapotranspiration is questionable. In order to ensure more reliability, the systems should be designed to include soil absorption. The successful use of these systems for intermittent usage has been noted in literature. Taking into consideration the issues discussed above, subsurface disposal of effluent is the safest under most conditions. This is provided the facility has been designed to accommodate site conditions. The main problem associated with subsurface disposal is the formation of a clogging mat on the infiltrative surfaces. Due to the formation of the clogging mat, the capacity of the soil to handle effluent is no longer governed by the soil’s hydraulic conductivity as measured by the percolation test, but rather by the infiltration rate through the clogged zone. The characteristics of the clogging mat have been shown to be influenced by various soil and effluent characteristics. Secondly, the mechanisms of clogging mat formation have been found to be influenced by various physical, chemical and biological processes. Biological clogging is the most common process taking place and occurs due to bacterial growth or its by-products reducing the soil pore diameters. Biological clogging is generally associated with anaerobic conditions. The formation of the clogging mat provides significant benefits. It acts as an efficient filter for the removal of microorganisms. Also as the clogging mat increases the hydraulic impedance to flow, unsaturated flow conditions will occur below the mat. This permits greater contact between effluent and soil particles thereby enhancing the purification process. This is particularly important in the case of highly permeable soils. However the adverse impacts of the clogging mat formation cannot be ignored as they can lead to significant reduction in the infiltration rate. This in fact is the most common cause of soil absorption systems failure. As the formation of the clogging mat is inevitable, it is important to ensure that it does not impede effluent infiltration beyond tolerable limits. Various strategies have been investigated to either control clogging mat formation or to remediate its severity. Intermittent dosing of effluent is one such strategy that has attracted considerable attention. Research conclusions with regard to short duration time intervals are contradictory. It has been claimed that the intermittent rest periods would result in the aerobic decomposition of the clogging mat leading to a subsequent increase in the infiltration rate. Contrary to this, it has also been claimed that short duration rest periods are insufficient to completely decompose the clogging mat, and the intermediate by-products that form as a result of aerobic processes would in fact lead to even more severe clogging. It has been further recommended that the rest periods should be much longer and should be in the range of about six months. This entails the provision of a second and alternating seepage bed. The other concepts that have been investigated are the design of the bed to meet the equilibrium infiltration rate that would eventuate after clogging mat formation; improved geometry such as the use of seepage trenches instead of beds; serial instead of parallel effluent distribution and low pressure dosing of effluent. The use of physical measures such as oxidation with hydrogen peroxide and replacement of the infiltration surface have been shown to be only of short-term benefit. Another issue of importance is the degree of pretreatment that should be provided to the effluent prior to subsurface application and the influence exerted by pollutant loadings on the clogging mat formation. Laboratory studies have shown that the total mass loadings of BOD and suspended solids are important factors in the formation of the clogging mat. It has also been found that the nature of the suspended solids is also an important factor. The finer particles from extended aeration systems when compared to those from septic tanks will penetrate deeper into the soil and hence will ultimately cause a more dense clogging mat. However the importance of improved pretreatment in clogging mat formation may need to be qualified in view of other research studies. It has also shown that effluent quality may be a factor in the case of highly permeable soils but this may not be the case with fine structured soils. The ultimate test of onsite sewage treatment system efficiency rests with the final disposal of effluent. The implication of system failure as evidenced from the surface ponding of effluent or the seepage of contaminants into the groundwater can be very serious as it can lead to environmental and public health impacts. Significant microbial contamination of surface and groundwater has been attributed to septic tank effluent. There are a number of documented instances of septic tank related waterborne disease outbreaks affecting large numbers of people. In a recent incident, the local authority was found liable for an outbreak of viral hepatitis A and not the individual septic tank owners as no action had been taken to remedy septic tank failure. This illustrates the responsibility placed on local authorities in terms of ensuring the proper operation of onsite sewage treatment systems. Even a properly functioning soil absorption system is only capable of removing phosphorus and microorganisms. The nitrogen remaining after plant uptake will not be retained in the soil column, but will instead gradually seep into the groundwater as nitrate. Conditions for nitrogen removal by denitrification are not generally present in a soil absorption bed. Dilution by groundwater is the only treatment available for reducing the nitrogen concentration to specified levels. Therefore based on subsurface conditions, this essentially entails a maximum allowable concentration of septic tanks in a given area. Unfortunately nitrogen is not the only wastewater pollutant of concern. Relatively long survival times and travel distances have been noted for microorganisms originating from soil absorption systems. This is likely to happen if saturated conditions persist under the soil absorption bed or due to surface runoff of effluent as a result of system failure. Soils have a finite capacity for the removal of phosphorus. Once this capacity is exceeded, phosphorus too will seep into the groundwater. The relatively high mobility of phosphorus in sandy soils have been noted in the literature. These issues have serious implications in the design and siting of soil absorption systems. It is not only important to ensure that the system design is based on subsurface conditions but also the density of these systems in given areas is a critical issue. This essentially involves the adoption of a land capability approach to determine the limitations of an individual site for onsite sewage disposal. The most limiting factor at a particular site would determine the overall capability classification for that site which would also dictate the type of effluent disposal method to be adopted.

Performance reporting : assessing the annual reports of Malaysian local authorities

There have been calls for Malaysian local authorities to be more transparent and accountable in the discharge of their functional responsibilities. This study empirically evaluates the extent and quality of current performance reporting by local authorities. The disclosure of relevant information for discharging accountability obligations, as defined by a broad range of stakeholders, falls short of best practice. Therefore, the performance of Malaysian local authorities lacks transparency. The findings could assist in the development of more comprehensive guidelines for local authority reporting and raise awareness of information stakeholders expect to be reported in the context of accountability

Experimental evaluation of the culture performance of three exotic and a ‘local’ Giant Freshwater Prawn (Macrobrachium rosenbergii, De Man 1879) culture strain in Fiji

Giant freshwater prawn (GFP; Macrobrachium rosenbergii) aquaculture has expanded rapidly since 1990. Most local culture industries, however, have developed in an unsystematic way. Fiji has a small culture industry producing the ‘Anuenue’ strain; however, performance of this strain has never been systematically evaluated. Recently, some Fijian farmers have reported declines in stock productivity. The current project evaluated the relative performance of three exotic strains with different genetic backgrounds from Malaysia, Indonesia and Vietnam, against the ‘local’ strain in Fiji in a 4 × 3 replicated pond trial experiment. A total of 5827 prawns were harvested after 143 days growout. Individual growth rate and relative survival of the Fiji strain were not statistically different from any of the introduced strains, but Vietnam strain was superior to that of the Malaysia strain. Genetic diversity showed significant differences in variability among strains, with the Malaysian strain displaying the lowest genetic diversity. Indonesia strain showed that females were reaching maturation earlier than other strains and were smaller in size. This study suggests that Malaysian and Indonesian strains would constitute a poor choice for Fiji, whereas the Vietnam strain consistently performed well on all criteria measured. High variation among replicate ponds within strains unfortunately confounded among-strain variation.

Drugs and local chemical mediators

10.1 Histamine and cytokines 10.1.1 Actions of histamine 10.1.2 Drugs that modify the actions of histamine 10.1.3 Cytokines 10.2 Eicosanoids 10.2.1 Cyclooxygenase (COX) and lipooxygenase system 10.2.2 Actions of eicosanoids 10.2.3 Drugs that modify the actions of eicosanoids 10.2.3.1 Inhibit phospholipase A2 10.2.3.2 Non-selective cyclooxygenase inhibitors 10.2.3.3 Selective COX-2 inhibitors 10.2.3.4 Agonists at prostaglandin receptors 10.2.3.5 Leukotriene receptor antagonists 10.3. 5-Hydroxtryptamine (serotonin), nitric oxide, and endothelin 10.3.1 5-HT and migraine 10.3.2 5-HT and the gastrointestinal tract 10.3.3 Nitric oxide and angina 10.3.4 Nitric oxide and erectile dysfunction 10.3.5 Endothelin and pulmonary hypertension

Local hormones

Local hormones or autocoids are chemical mediators that are secreted by one group of cells to affect the function of other nearby cells. This eChapter covers a diverse range of these mediators, their physiological effects, pathological implications and clinical use of drugs and other agents that target these systems...

Forging the heteroglossic citizen : articulating local, national, regional and global horizons in the Australian Curriculum

This article offers a discourse analysis comparing selected articles in the national press over the consultative period for Phase 1 subjects in the new Australian Curriculum, with rationales prefacing official Australian Curriculum Assessment and Reporting Authority documents. It traces how various versions of Australia, its ‘nation-ness’ and its future citizens have been taken up in the final product. The analysis uses Lemke's analytic elaboration of Bakhtin's concept of heteroglossia and its derivative, intertextuality. It identifies a range of intertextual thematic formations around ‘nation’, ‘history’, ‘citizen’ and ‘curriculum’ circulating in the public debates, then traces their presence in official curriculum documents. Rather than concluding that these themes are contradictory and incoherent, the conclusion asks how these multiple dialogic facets of Australian nation-ness potentially offer a better response to complex times than any coherent monologic orthodoxy might.

An index of best practice performance reporting for Malaysian local authorities

Abstract Purpose – The purpose of this paper is to identify stakeholders’ expectations of information to be conveyed in local authorities’ annual reports and to develop an index of best practice performance reporting. Design/methodology/approach – The paper describes the development of a disclosure index emphasizing the public interest aspect of reporting and the need to provide relevant and meaningful information to stakeholders. The index was crafted from a public accountability perspective and based on the expectations of stakeholders as reconciled and validated by a Delphi panel of experts. Findings – The wide scope of information that was dentified as being important for disclosure by local authorities is consistent with the public accountability paradigm which requires the reporting of comprehensive information (both financial and non financial), about the condition, performance, activities and progress of the entity. Originality/value – The research posits a model of best practice performance reporting for Malaysian, and other, local authorities to meet the need for greater accountability by these entities.

Broadband today : the role of Australian local government authorities

The paper seeks to clarify the role of Local Government Authorities in facilitating the Australian digital economy. It does this by analysing responses to the 2012 BTA, NBN and Digital Economy Survey. This reveals the level of recognition by LGAs of relevant issues; their level of use of federal, state and other programs designed to enable end user engagement; and other actions LGAs are undertaking to enable their regional digital economies. The analysis reinforces the significant role of LGAs in the future of Australia’s digital economy and identifies areas where assistance may be required.

Diversification for sustainable development in rural and regional Australia : how local community leaders conceptualise the impacts and opportunities from agriculture, tourism and mining

Although the multiple economic, environmental and social challenges threatening the viability of rural and regional communities in Australia are well-known, little research has explored how community leaders conceptualise the impact and opportunities associated with economic diversification from agriculture into alternative industries, such as tourism and mining. This qualitative research, utilising the Darling Downs in Queensland as a case study, documents how 28 local community leaders have experienced this economic diversification process. The findings reveal that local community leaders have a deep understanding about the opportunities and challenges presented by diversification, articulating a clear vision about how to achieve the best possible future for their region. Despite excitement about growth, there were concerns about preserving heritage, the increased pressure on local infrastructure and an ageing population. By documenting local leader’s insights, these findings may help inform planning for rural and regional communities and facilitate management of the exciting yet challenging process of growth and diversification

The roles of procedural justice and social learning in improving self organizing capabilities of local communities for sustainable development in decentralized Indonesia

The development planning process under Law No. 25/2004 is said to be a new approach to increase public participation in decentralised Indonesia. This Law has introduced planning mechanisms, called Musyawarah Perencanaan Pembangunan (Musrenbang), to provide a forum for development planning. In spite of the expressed intention of these mechanisms to improve public participation, some empirical observations have cast doubt on the outcomes. As a result, some local governments have tried to provide alternative mechanisms to promote for participation in local development planning. Since planning is often said to be one of the most effective ways to improve community empowerment, it is of particular concern, to examine the extent to which the current local development planning processes in Indonesia provide sufficient opportunities to improve the self organising capabilities of communities to sustain development programs to meet local needs. With this objective in mind, this paper examines problems encountered by the new local planning mechanism (Musrenbang) in increasing local community empowerment particularly regarding their self organising capabilities. The concept of community empowerment as a pathway to social justice is explored to identify its key elements and approaches and to show how they can be incorporated within planning processes. Having discussed this, it is then argued that to change current unfavorable outcomes, procedural justice and social learning approaches need to be adopted as pathways to community empowerment. Lastly it is also suggested that an alternative local planning process, called Sistem Dukungan (SISDUK), introduced in South Suluwezi in collaboration with JAICA in 2006 (?) offers scope to incorporate such procedural justice and social learning approaches to improve the self organizing capabilities of local communities.

Integrated TEM, XRD and electron-microprobe investigation of mixed-layer chlorite smectite from the Point-Sal ophiolite, California

Five basalt samples from the Point Sal ophiolite, California, were examined using HRTEM and AEM in order to compare observations with interpretations of XRD patterns and microprobe analyses. XRD data from ethylene-glycol-saturated samples indicate the following percentages of chlorite in mixed-layer chlorite-smectite identified for each specimen: (i) L2036 almost-equal-to 50%, (ii) L2035 almost-equal-to 70 and 20%, (iii) 1A-13 almost-equal-to 70%, (iv) 1B-42 almost-equal-to 70%, and (v) 1B-55 = 100%. Detailed electron microprobe analyses show that 'chlorite' analyses with high Si, K, Na and Ca contents are the result of interlayering with smectite-like layers. The Fe/(Fe + Mg) ratios of mixed-layer phyllosilicates from Point Sal samples are influenced by the bulk rock composition, not by the percentage of chlorite nor the structure of the phyllosilicate. Measurements of lattice-fringe images indicate that both smectite and chlorite layers are present in the Point Sal samples in abundances similar to those predicted with XRD techniques and that regular alternation of chlorite and smectite occurs at the unit-cell scale. Both 10- and 14-angstrom layers were recorded with HRTEM and interpreted to be smectite and chlorite, respectively. Regular alternation of chlorite and smectite (24-angstrom periodicity) occurs in upper lava samples L2036 and 1A-13, and lower lava sample 1B-42 for as many as seven alternations per crystallite with local layer mistakes. Sample L2035 shows disordered alternation of chlorite and smectite, with juxtaposition of smectite-like layers, suggesting that randomly interlayered chlorite (< 0.5)-smectite exists. Images of lower lava sample 1B-55 show predominantly 14-angstrom layers. Units of 24 angstrom tend to cluster in what may otherwise appear to be disordered mixtures, suggesting the existence of a corrensite end-member having thermodynamic significance.

Disaster resilience and local adaptation capacity in coastal Queensland

The 2011 floods illustrated once again Queensland’s vulnerability to flooding and similar disasters. Climate change will increase the frequency and magnitude of such events and will have a variety of other impacts. To deal with these impacts governments at all levels need to be prepared and work together. Like the rest of the nation most of the population of the state is located in the coastal areas and these areas are more vulnerable to the impacts of climate change. This paper examines climate change adaptation efforts in coastal Queensland. The aim is increasing local disaster resilience of people and property through fostering coordination between local and state government planning activities in coastal high hazard areas. By increasing the ability of local governments and state agencies to coordinate planning activities, we can help adapt to impacts of climate change. Towards that end, we will look at the ways that these groups currently interact, especially with regard to issues involving uncertainty related to climate change impacts. Through an examination of climate change related activities by Queensland’s coastal local governments and state level planning agencies and how they coordinate their planning activities at different levels we aim to identify the weaknesses of the current planning system in responding to the challenges of climate change adaptation and opportunities for improving the ways we plan and coordinate planning, and make recommendations to improve resilience in advance of disasters so as to help speed up recovery when they occur.

Framing local stories for community consumption facilitation and evaluation in narrative driven arts-based projects

Cyclone Yasi struck the Cassowary Coast of Queensland in the early hours of Feb 3, 2011, destroying many homes sand property, including the destruction of the Cardwell and district historical society’s premises. With their own homes flattened, many were forced to live in mobile accommodation, with extended family, or leave altogether. The historical society members however were more devastated by their flattened foreshore museum and loss of their collection material. A call for assistance was made through the OHAA Qld branch, who along with QUT sponsored a trip to somehow plan how they could start to pick up the pieces to start again. This presentation highlights the need for communities to gather, preserve and present their own stories, in a way that is sustainable and meaningful to them, but that good advice and support along the way is important. Two 2 day workshops were held in March and then September, augmented by plenty of email correspondence and phone calls in between. Participants learnt that if they could conduct quality oral history interviews, they could later use these in many exhibitable ways including: documentary pieces; digital stories; photographic collections; creative short stories; audio segments –while also drawing closely together a suffering community. This story is not only about the people who were interviewed about the night Yasi struck, but the amazing women (all over 50) of the historical society who were willing to try and leap the digital divide that faces older Australians, especially those in rural Australia, so that their older local stories would not be lost and so that new stories could also be remembered.

‘The health-location connection’: using GIS and social media on smartphones to track engagement with the Local urban environment for work, recreation, and physical activity

A technologically innovative study was undertaken across two suburbs in Brisbane, Australia, to assess socioeconomic differences in women's use of the local environment for work, recreation, and physical activity. Mothers from high and low socioeconomic suburbs were instructed to continue with usual daily routines, and to use mobile phone applications (Facebook Places, Twitter, and Foursquare) on their mobile phones to ‘check-in’ at each location and destination they reached during a one-week period. These smartphone applications are able to track travel logistics via built-in geographical information systems (GIS), which record participants’ points of latitude and longitude at each destination they reach. Location data were downloaded to Google Earth and excel for analysis. Women provided additional qualitative data via text regarding the reasons and social contexts of their travel. We analysed 2183 ‘check-ins’ for 54 women in this pilot study to gain quantitative, qualitative, and spatial data on human-environment interactions. Data was gathered on distances travelled, mode of transport, reason for travel, social context of travel, and categorised in terms of physical activity type – walking, running, sports, gym, cycling, or playing in the park. We found that the women in both suburbs had similar daily routines with the exception of physical activity. We identified 15% of ‘check-ins’ in the lower socioeconomic group as qualifying for the physical activity category, compared with 23% in the higher socioeconomic group. This was explained by more daily walking for transport (1.7kms to 0.2kms) and less car travel each week (28.km to 48.4kms) in the higher socioeconomic suburb. We ascertained insights regarding the socio-cultural influences on these differences via additional qualitative data. We discuss the benefits and limitations of using new technologies and Google Earth with implications for informing future physical and social aspects of urban design, and health promotion in socioeconomically diverse cities.