Since the amalgamation of the Auckland Council’s in 2010 and the separation of stormwater management from potable water and wastewater, much has changed in the way stormwater maintenance is now being delivered across the region.
The short-term maximum acceptable value (MAV) for drinking water in NZ is 11.3 mg/L nitrate-N, which follows the accepted World Health Organization (WHO) Guideline Value. Risk maps have been produced which show that groundwater sites with nitrate concentrations that breach health standards are found in most regions, but are most common in dairying regions. In the Waikato, elevated nitrate concentrations have also been attributed to market gardening in areas where free-draining soils overlie a shallow water table.
Algae-based wastewater treatment processes are often heralded for their high sustainability. However, this view is challenged by recent demonstrations of the ability of axenic microalgae to synthesize nitrous oxide (N2O), a powerful greenhouse gas and ozone-depleting atmospheric pollutant.
he New Zealand’s greenhouse gases inventory currently uses a country-specific methodology to compute methane emissions occurring during farm dairy manure management. Unfortunately, this methodology is mathematically flawed and based on highly uncertain and potentially irrelevant data.
Parliament is debating the Local Government Act 2002 Amendment Bill (No. 3), that includes a requirement for local authorities to prepare an infrastructure strategy for a 30 year period. Although this may seem onerous, infrastructure planning for water and wastewater utilities can be effectively streamlined by focusing on two main elements: capacity and condition.
This paper describes the GIS identification of stormwater quality device retrofit locations which form the basis of the mitigation options. An engineering constraints approach informed a complex GIS analysis across the entire catchment. The analysis extended to sizing and costing the devices within the GIS model for two types of treatment device with the overall goal of informing a benefit-cost analysis. The GIS approach enabled easy modification and validation of the proposed retrofit locations as well as visualisation of potential options for future of stormwater management within the catchment.
To determine if the conditions present in algal WWT systems enhance the removal of emerging pollutants, the fate of tetracycline is being evaluated in lab-scale high rate algal ponds (HRAP) continuously fed with clarified domestic wastewater. Results thus far show up to 90% removal of tetracycline when fed at an influent concentration of 2 mg/L. A current major difficulty is ensuring the lab-scale HRAPs maintain a steady representation of full-scale conditions.
The New Zealand Defence Force (NZDF) owns and operates a Wastewater Treatment Plant (WWTP) at Waiouru, which was originally built in 1957. The WWTP treats wastewater generated from the NZDF military base and from commercial and residential sources within the township, and discharges the treated wastewater (effluent) to a nearby stream. The treatment plant needed upgrading to comply with new discharge consent limits and PDP was engaged to undertake this work after assisting NZDF to obtain the new discharge consent.
This paper presents the selection process, design considerations, one year operational experience, operator input and performance of the first full scale solar drying facility in New Zealand.
This paper describes the process that Palmerston North City Council followed in transforming low rate digesters into high rate digesters and thereby enabling sufficient biogas generation to run a new 716kW Electrical generator. The paper describes the process for determining the requirements of the project, how the cost benefit was derived the generator selection methodology and how the improvements to digester performance were identified and implemented.
The control system sector within the water and wastewater industry is constantly changing. New technologies, techniques and equipment are continuously pushing the boundaries of what can be achieved. However, from this questions can arise such as, “should all these new techniques be adopted?” and “do they add value?”.
There are many municipal wastewater treatment plants (WWTP’s) in New Zealand that are treating large industrial wastewater loads. Treating these large industrial loads can be challenging due to the characteristics and variability of the wastewater. Often these WWTP’s are located in rural towns where financial constraints have a large influence on the plant design. The Te Kuiti WWTP is one of these plants and underwent a significant upgrade in 2012/13.
Engineers Without Borders New Zealand is a not-for-profit organisation that connects, educates and empowers people through humanitarian engineering. The objective of international development is to create a better world free from poverty. Engineers Without Borders New Zealand believes that access to engineering knowledge and resources can make a positive difference in this respect. The organisation has two core portfolios that enable members this difference.
Industrial and trade waste discharged to sewer has the potential to cause process problems in receiving biological waste water treatment plants (WWTP) and advanced water reuse plants (AWP). Detection and quantification of intermittent and short lived industrial discharges by random discrete sampling is costly and unreliable because a large number of samples must be analysed for a range of possible contaminants with no guarantee of detection. Composite sampling is also problematic as averaging over a day or week makes it difficult to identify discrete discharges. Online monitoring for trade waste discharges is an efficient alternative.
The Hamilton City Council (HCC) initiated in 2012 the upgrade of its Pukete treatment plant digesters for treatment of increased biosolids loads (> 60 % load increase expected in next decade). Capacity upgrade was achieved in existing digesters and without plant operation interruption.
This paper sets out some of the benefits and challenges of regulation, drawing on examples from the United Kingdom (UK). It discusses a range of issues relating to regulatory models, including possible economic models and frameworks for ensuring compliance and the protection of the environment and drinking water standards. The issue of privatisation versus regulation is also considered.
This paper is an on-site study of the treatment plant aeration system and how it is affecting the activated sludge process. The purpose of this paper is to assist the WBOPDC in making a more informed decision about the aeration upgrade.
This article briefly discusses the theory of carbonate chemistry and how to improve water stability using the remineralisation process. It will also discuss the challenges of designing this system for the Wheatstone LNG plant to be constructed by Xylem Water Solutions (Australia).
Initial investigations for future wastewater treatment schemes in Featherston showed that infiltration and inflow (I/I), especially groundwater infiltration (GWI), was at such a level that the cost of any scheme would be highly influenced by the excessive flow volume. This project was commissioned to determine the level and extent of network rehabilitation required to achieve the lowest overall cost for future high rate treatment and land based treatment and disposal options.
The existing Water Treatment Plants (WTPs) in the Southland District Council (SDC) communities of Te Anau, Mossburn, Otautau, and Winton required improvements to comply with the Drinking-water Standards for New Zealand 2005 (Revised 2008) (DWSNZ). All existing supplies were similar, consisting of shallow bore water sources, primary pumping, and chlorine gas disinfection, followed by secondary pumping into the reticulation where needed.
This paper presents an example of the implementation of operator certification and training schemes into Veolia’s operations and the resulting benefits to our organization at the local, regional and national level.
Building on an already strong relationship between the councils, Waipa and Waikato District Councils and Hamilton City Council developed the Sub Regional Waters Group – Shared Services in 2011.
This paper outlines how the Stronger Christchurch Infrastructure Rebuild Team (SCIRT) went about reducing leakage from the potable water supply network to pre-earthquake level and reforming how the water supply network is viewed, worked on and managed. The question authorities in New Zealand’s other urban centres may be asking is: how unique were the circumstances described to Christchurch & what of this applies to us?