This case study presents the methodology used to achieve the model validation and the development of current and future peak day scenarios, and the field test plan. The role of the schematic and novel approaches to developing simple model representations of real life operations are presented. This case study will be of interest to modellers dealing with large networks and their managers, and will show a realistic pragmatic approach to model validation, field test planning and the simulation of a large and complex network.
This paper shows how to improve anaerobic digester start-up performance through use of purpose designed biological commissioning procedures. Key data and features for the presented examples are discussed.
Disposal of poorly-treated wastewaters from households and communities can pollute ground- and surface-waters, reducing water quality, and creating risks for human health and negative impacts on aquatic ecosystems. Constructed wetlands have the potential to reliably treat septic tank effluents to advanced secondary or tertiary standards with nil or low requirements for energy or mechanical equipment. Because they harness robust natural treatment processes and have extended residence times, they are likely to be more able to deal with fluctuations in usage and loading than mechanised package treatment plants (particularly those based on activated sludge processes), nd be less reliant on technical maintenance.
Wastewater treatment High Rate Algal Pond algal biomass consists of colonial algae that aggregate with bacteria to form large floccs. Large floccs have a smaller surface area to mass or volume ratio and due to their lower drag can be efficiently removed from HRAP effluent by gravity sedimentation in simple algal settling cones with a hydraulic retention time of 3 to 6 hours. This paper investigates the potential to use tube settlers to enhance algal harvest efficiency and reduce the hydraulic retention time required for harvest. The settling efficiency of tube settlers is affected by two major parameters; the angle of incline of the tube (which affects the maximum settling depth), and the flow rate (which affects the hydraulic retention time).
This paper presents the results of experiments on psychrophilic anaerobic digestion of algal biomass harvested from wastewater treatment HRAP and the influence of organic loading rate and ammonia concentration on digestion efficiency.
In 2010, two 7,000m³ anaerobic digesters were commissioned at the Christchurch Wastewater Treatment Plant (CWTP), which now operates a Temperature Phased Anaerobic Digestion (TPAD) process – thermophilic and mesophilic in series. This paper outlines the thermophilic commissioning process including difficulties, solutions and contingency plans, and the improvement in digester performance.
Surface water bodies are normally linked to groundwater. Rivers, lakes, wetlands and estuaries may act as recharge sources for an aquifer or vice versa (Braaten and Gates, 2001). Understanding the basic principles of groundwater/surface water (GW–SW) interactions is essential to effectively manage water resources. The necessity for sustainable use of groundwater and surface water in New Zealand will continue to increase in the future due to global warming, contamination of water resources and increasing demand for water. A good understanding of groundwater-surface water interactions is important for decision makers and water resources managers.
There is no formal information on overall water use in New Zealand commercial office buildings, or on how much water a building might be expected to use for a given purpose. Over the past three years this study has undertaken multiple investigations of daily water usage and patterns, as well as overall building water audits to help resolve this gap in New Zealand commercial building literature.
SBR (sequential batch reactor technology) is widely introduced in New Zealand and overseas as a modern wastewater treatment process. The SBR process enjoys growing popularity worldwide and is based on the principle that treatment of wastewater works significantly better under defined volume conditions. Classic sewage plant technologies (i.e. continuous flow plants) cannot provide the same process stability.
This paper focuses on Yarra Valley Waters’ reasons for the efficiency study program, the methodology used to undertake these investigations, including some of the difficulties the project team came across and the results of the changes from the process model outputs.
In a world-first application of Chilean technology, Clutha District Council constructed a trial Biofiltro plant to further treat the Kaka Point oxidation pond effluent before its discharge to the sea. The context of the consenting environment for the Kaka Point and other treated sewage discharges in the Clutha District produced some pressure on the Council to find an affordable solution for its urban communities so that their viability would not be threatened, while meeting enhanced environmental standards.
The concept and objectives for the upgrade was to future-proof the WwTP and to optimise and utilise existing Council assets. The plant was to meet future increased flows and loads whilst achieving a greatly improved effluent quality. With the treated effluent discharging into the Mangawhero Stream this would provide a positive outcome for the local community and would have significant social benefits.
This paper presents the methodology of the capacity study, the selection of the membrane type and the configuration of the membrane bioreactor.
An innovative approach to dynamic modelling of pressure sewer systems is outlined. The effect of this approach on the number of simultaneous pump runs for a given system and the consequential beneficial effects on hydraulic characteristics of the pressure sewer system is discussed. The innovative dynamic modelling approach is compared to typical system outputs and the effects on retention time, post power outage recovery and other hydraulic characteristics.
Aloe vera is a species of Aloe, native to northern Africa. It is a stemless or very short-stemmed succulent plant. Aloe vera is now widely used in cosmetic and alternative medicine industries. In this study, the coagulation performance of rind from Aloe vera was investigated for the first time. Rind of A. vera was evaluated for turbidity removal from synthetic turbid water samples by using jar test. A. vera rind coagulant was extracted with different concentration of sodium chloride (AvC-SC) from ground rind shows high turbidity removal up to 90%.
New Zealand produces around a billion litres of municipal wastewater per day. (inf-facts-issues-Sep09.pdf, 2009) Currently very little of this effluent is used for farm irrigation, despite declining water resources in many areas. A key obstacle to uptake of treated wastewater is perception. Thus whilst technology is sufficiently advanced to ensure that public health risks are acceptable in a scientific sense, there is a knowledge gap in achieving cultural acceptability.
This paper looks at the merits of managing the 3 waters on an individual house lot. Research shows this approach can halve potable water use, alleviate stormwater run-off, and reduce the wastewater by 45%. This can lead to existing infrastructure having the capability to support double the amount of housing. Having a decentralized water supply network also improves the community’s resilience to disasters.
Much of the infrastructure in the City of Dunedin, was developed during the boom years following the discovery of gold in the region in the 1860s. Subsequent periods of population decline and recession left a legacy of ageing infrastructure and substantial deferred investments in water renewals, which presented a significant problem for the current generation to address. To sustainably meet the present and future needs of the city, a new approach to the planning and management of the water infrastructure was required.
This paper presents the path taken to enable the effective planning, development, governance and delivery of the Project (which was completed in 2011) and reflects on some of the lessons learned that have arisen as a result of this experience.