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Sustainable Wastewater Management: A handbook for smaller communities

Opening section

Foreword and Acknowledgments

He Mihi

Introduction

Part 1: Understanding wastewater within natural and human systems

Part 2: Negotiating the maze

Part 3: Options for wastewater servicing

Part 4: Management, Funding And Selection Of Wastewater Options

Part 5: Glossaries, abbreviations, appendices and information sources

Appendices

Appendix 1 Examples of ecosystem goods and services

Appendix 2 Legislation relevant to wastewater management

The Resource Management Act 1991 (RMA)

The RMA controls most of the consents your community will need. The purpose of the Act is to promote the sustainable management of natural and physical resources. It provides for the preparation of regional policy statements, policies and plans, and the preparation of district plans. The control of specific activities is achieved through the rules in these plans and through resource consents.

The RMA does not explicitly provide for the management of waste: it provides for the management of environmental effects, including those arising from the disposal of waste as part of a wider focus on the effects of actions on the environment. The Act requires that adverse effects are avoided, mitigated or remedied.

The RMA is an enabling piece of legislation that provides councils with considerable discretion and opportunity in its interpretation.

The Hazardous Substances and New Organisms Act 1996 (HSNO)

This Act provides for the protection of the environment by preventing or managing risks to the environment from hazardous substances and new organisms.

The HSNO legislation takes a life-cycle approach to the management of hazardous substances, including their disposal, when such substances are no longer wanted and become waste. The disposal of waste hazardous substances is controlled through the Hazardous Substances (Disposal) Regulations 2001. These regulations provide for the treatment of the different classes of waste hazardous substances before disposal so that the substances are no longer hazardous.

The Health Act 1956

This requires territorial authorities to ensure waste is collected and disposed of, promote and protect public health, and report diseases and unsanitary conditions to the medical officer of health. The local authority must 'secure the abatement' of any nuisance likely to injure or be offensive to health.

The Local Government Act 2002

The Local Government Act 1974 was reviewed in 2002. The new Act requires local authorities to take a sustainable development approach. Section 125 requires a territorial authority to assess the provision of wastewater services within its district from time to time. An assessment may be included in the territorial authority's long-term council community plan, but if it is not, the territorial authority must adopt the assessment using the special consultative procedure.

The Local Government Act 2002 contains provisions relating to tradewastes, stormwater, sewage and waste management planning. Tradewastes are generally managed through bylaws. Traditionally the control on tradewastes was to prevent the wastes from harming the sewerage or wastewater network, but increasingly bylaws are being used to control the nature and concentrations of substances in order to manage the type of treatment and final discharge of wastes.

Key themes in the Act which impact wastewater management are summarised below.

• Sustainable communities: the overall purpose of local authorities is to promote the community's social, economic, environmental and cultural wellbeing. These four factors have to considered in every significant wastewater decision a council makes. (This handbook has focused on all four factors.)
• Long-term planning: councils must determine their community's long-term outcomes and priorities in an integrated way, and this process must include provision for public submissions. In addition, each council must prepare a 'long-term council community plan' which shows what the local authority intends to do towards achieving the desired outcomes.
• Consultation: in determining community outcomes and priorities, in planning and when making significant decisions, local authorities must engage in public consultation.

In addition to these general themes there are specific new provisions in the Act relating to the management of wastewater.

• Part 7 of the Act requires local authorities to make "an assessment" of water services from time to time. This requires an exhaustive examination of the water, sewerage and stormwater functions, including present arrangements, future demand, delivery options and conservation strategies. The assessment is subject to a public consultation process and it (or a summary of it) must be included in the council's long-term council community plan.
• Section 130 obliges local authorities to maintain water services.
• Section 131 allows local authorities to close down small water services – but only after a referendum.
• Section 136 limits contracts for water services operations to 15 years and in these circumstances it must retain control over pricing, management and the development of policy.

Appendix 3 Wastewater production, water consumption and water-conserving technologies

Wastewater production

Table A1 sets out information on wastewater production based on data from Christchurch. This information would be typical of most communities on a public water supply.

Table A2 shows the amount of phosphorous and nitrogen produced. Both of these have a major impact on the nutrient cycle and need treatment.

If urine is diverted from the domestic wastewater, and greywater and toilet flushing is reduced by 50% by using more efficient water technologies in each home, the volume of domestic wastewater going to a wastewater treatment plant could be reduced by over 50%. This would also mean nitrogen going to treatment would be reduced by 80%, and phosphorous by 30%.

Water consumption

Water consumption per person varies from town to town and throughout the year. Obviously water consumption will increase considerably in the summer when people water their gardens and lawns.

Waimakariri District Council estimates a peak domestic daily water requirement of 1,000 to 1,500 litres per person. This includes a rather generous allowance for garden and lawn irrigation requirements. For Christchurch City, peak daily per capita water consumption is up to 2,000 litres, while the minimum is 200 litres. The daily average is 450 litres/person. These figures are based on city-wide consumption figures, which will include water consumed by industry and commercial activities.

For a small community in a rural area, industry and commercial uses will usually be quite small. The typical water consumption rate for household activities (excluding uses such as garden irrigation, car washing and swimming pool use) is about 180–200 litres person per day.

Water-saving technologies

Table A3 is an illustration of possible water savings using water-saving technologies.

Toilets

There are now a number of different toilet designs available in porcelain, stainless steel and plastic. The volume of wastewater coming from the different toilets varies considerably. These systems include:

• water-saving (usually dual-flush) toilets
• vacuum toilets
• composting toilets.

For each of these systems there may be the option of a urine-separating design, or the traditional non-separating design producing blackwater. For those systems with urine separation there is a separate urine-flushing mechanism, which uses considerably less water than the faeces flush.

The older type of single-flush toilets would use up to 15 to 20 litres of water per flush. Many older homes are likely to have these types of toilets. The dual-flush toilets have flushing volumes ranging from full flush to reduced flush volumes of 11 to 5.5 litres, 6 to 3 litres and 3.3 to 1.5 litres.

Vacuum toilets

Vacuum toilets are now used overseas in residential units. Several home units (eg, in an apartment block or cluster homes) may be served by a single vacuum unit. There are also single-toilet vacuum units. The volumes of wastewater from vacuum toilets are very low. Typical daily flush volumes for 1 EDU²² (representing one average household) using these toilets are given in Table A4. It can be seen from this table that volumes of blackwater can vary considerably with the type of toilet used.

Urine-separating vacuum toilets are being used in some countries in Europe. While it can be seen from Table A4 that this reduces volumes considerably, the other advantage is that it enables the recovery of the nutrients from the urine. Urine is rich in nutrients and typically contains 85% of the nitrogen and 50% of the phosphorus in the total domestic wastewater stream. The other advantage in separating out the urine is that it enables the return of these nutrients back to productive land use. Research carried out on the health risk of separated urine by the Swedish Institute for Infectious Disease Control²³ shows that:

• E. coli and other coliforms die off quickly in stored urine
• some micro-organisms such as faecal streptococci and the parasite Cryptosporidium survive longer than E. coli, and probably also some viruses
• the hygienic risks connected with human urine are a lot less than with faeces
• the amounts of hormones are very small compared to other sources, and we do not need to worry about them.

The application of urine separation and recovery technology in Scandinavia has enabled the conversion of urine into fertiliser at central processing facilities. Urine storage tanks associated with apartment blocks enable routine collection of the raw product, which is transferred in bulk to the processing plant. The resulting product is then sold for farm and horticultural use. No such proposals for urine recovery are under development in New Zealand.

Waterless urinals

BRANZ-certified waterless urinals have been installed in a number of men's toilets throughout New Zealand. Each urinal is made from fibreglass-reinforced plastic with a special gel-coat surface. Odour control and hygiene is achieved with a patented alcohol-based sealing fluid with trap.

Composting toilets and greywater systems

See Appendix 4.

Other water-using technologies

Washing machines

Low water-use washing machines can reduce laundry wastewater volumes by 30%. Typically, front-loading washing machines use less water than do top-loading washing machines. The September 1999 Consumer magazine (No. 385) evaluated a number of New Zealand-available washing machines, including a rating for efficiency of water use. Front-loading machines generally rated higher.

Fittings

There are various fittings that can reduce water use in homes and industry. Aerator fittings for shower heads and tap faucets have the effect of increasing the bulk of the aerated water stream, giving a sense of volume but with a reduced real volume of water. This can be effective in showering and hand washing.

Proprietary flow-control valves such as Jemflow and Aqualoc are inexpensive valves that claim to reduce water consumption by up to 35%. These can be fitted into new homes or retro-fitted into existing homes.

In situations where water pressure is higher than necessary, causing excessive flow rates, the fitting of pressure-reducing valves will save water consumption.

Greywater and blackwater separation with specific management

Separating the greywater from the blackwater enables separate management of these two components. There is at least one commercially available system in New Zealand for greywater treatment and recycling: the East Coast (ECO) Wastewater Recycling System (recently certified by BRANZ). Recycled greywater is used for toilet flushing and garden watering.

Conclusions

The key conclusions are as follows.

• Table A3 shows that internal domestic water use can be reduced by 50% with the adoption of water-saving technologies in the home.
• Table A4 clearly illustrates that substantial water volume reductions can be achieved according to the type of toilet installed. The organic and nutrient loading of blackwater from an EDU will not be affected by the type of toilet.
• The greywater component of the domestic wastewater volume can also be reduced by the use of water-saving technologies. Separating the greywater from the blackwater will enable separate and more appropriate management of these two streams. There may also be some situations where greywater recycling would be appropriate. However, on some sites greywater can be managed on-site, and this will reduce the hydraulic loading on centralised sites receiving treated wastewater.
• For existing homes and enterprises the economic benefits of retro-fitting water-saving (and hence wastewater reduction) technologies would need to be considered carefully. However, it is strongly recommended that new homes and commercial and service units give serious consideration to the installation of water-saving technologies and management techniques. The cost-benefit would need to be evaluated for each specific development.

Appendix 4 Composting toilets

Composting of human waste is an ancient practice. It is only in the last 30 years that systems for modern living have been designed and commercialised for the modern domestic home environment. (Sweden has pioneered these systems). A composting process relies on bacteria and other micro-organisms to break down the organic constituents of human faeces and other organic wastes under aerobic conditions (where oxygen is present).

For human waste to compost well there needs to be the correct moisture content (not too damp) and a balance of carbon and nitrogen components, and it needs to be well aerated. If not, problems may arise, including:

• odour
• flies and other nuisance insects.

Sound design and good management can overcome a number of these problems. Odour – and to a certain extent excess moisture – can be minimised with good ventilation. Most systems employ an electric fan for forced ventilation. Some systems provide additional heating to accelerate decomposition and moisture evaporation. Excess moisture may be avoided by using urine-separating toilets, although these are not common in New Zealand (see Appendix 3).

Various measures can be taken to minimise the fly problem, such as the use of insect screens and ensuring the compost chamber is sealed against insect access (keep the toilet lid closed when not in use). Other systems use a light trap to attract flies away from the pedestal, which is the most common means of access by flies to the composting chamber. A healthy composting process will attract fewer flies. However, this cannot always be guaranteed.

Management issues include:

• visual 'uncleanliness'
• the need for regular and acceptable compost removal and disposal.

Porcelain pedestals are generally easier to keep clean than plastic units. The suppliers of the composting toilet normally advise how toilet bowls should be cleaned.

Care needs to be taken in the handling and disposal of the composted material. After 12 months of well-managed composting it is recommended that the solids be stored for another 12 months before returning to land, preferably by burying in an area where potential human contact is low. If well composted there should be no objectionable smell (maybe an earthy, musty odour) and most pathogens are destroyed, making it safe for handling.

Other management issues related to usage include:

• the toilet lid should be closed at all times when not in use
• add no cigarette butts, sanitary towels or nappies, glass, metal, plastic, chemicals or toxic materials.

Composting toilets require on-site management. The obvious advantage of composting toilets is the non-liquidisation (by flush water) of faecal material and the avoidance of problems that liquid waste can cause.

At the same time, any owner wishing to install a composting toilet will need to make provision for the management of greywater. The usual method is to install a reduced-size septic tank in accordance with AS/NZS 1547:2000 followed by a conventional on-site re-entry system such as soakage trenches. Alternative approaches include the use of special grease and sediment traps, followed by a constructed wetland, with the resulting treated effluent being stored for garden irrigation or disposed by sub-soil soakage or dripline irrigation. Where a grease and sediment trap is used instead of a reduced-size septic tank, weekly or monthly maintenance of the trap will be required.

Local authorities have differing attitudes to the use of composting toilets, and you should consult your council to determine their rules related to acceptance and approval of this method of human waste management. It should also be noted that the Ministry of Health does not recommend the use of composting toilets in urban areas.

Appendix 5 New developments and innovations in wastewater servicing

New thinking in treatment technologies is tending to blur the boundary between treatment and re-entry systems. The focus now is on working with ecosystems to beneficially treat environmental pollutants. As with most technologies, new wastewater servicing systems are being researched and developed all the time. This appendix describes some of these developments in New Zealand and overseas. Most are not well proven systems under New Zealand conditions.

Constructed wetland developments

Staged planting wetlands have been used in the US, where up to five wetland units in series are each planted with specific plant species aimed at particular treatment functions, such as organic matter control, nutrient removal and bacterial control.

In septage wetlands the pump-out contents of septic tanks (the septage) is treated by flooding into a shallow basin, within which dense wetland plantings thrive on the nutrients in the solids. As the basin gradually fills at each dose of sludge and liquid, the root systems of the growing plants climb steadily up the older buried stalks. The whole mature sludge/root mass content is eventually excavated and composted, and the basin replanted for continuing use.

Controlled environment aquatics consist of a series of tank cells housed within a 'glasshouse' or other covered and sheltered environment. Treatment is carried out with a series of tanks containing floating plants interspersed with sub-surface flow cells. Some systems include fish tanks. Patented systems include Solar Aquatics, Living Machine and Biological Aquatics. These systems are not currently available in New Zealand.

Oxidation pond developments

The advanced integrated wastewater pond system (AIWPS) has been used in the US since the 1960s, although only to a limited extent. It is now being trialled in New Zealand. It is a five-stage pond system with a deep anaerobic and facultative first stage, followed by a high-rate algal race-track channel, a five-day settling pond, a deep-polishing pond for bacterial removal, and a final storage and maturation pond. The total through-flow time of 24 days compares with the 60 days for a traditional facultative/polishing pond combination, thus reducing the land area required. However, significant hands-on operational supervision is required to ensure the system performs to its optimum.

Reclaimed water developments

Reclamation of water from recirculating sand-filter systems via UV disinfection to enable recycling back onto properties for toilet flushing and closed-cycle garden irrigation is common in the US. A large Australian scheme known as the Rouse Hill project, to the west of Sydney, has been introduced to conserve the use of potable water in the face of restrictions on natural water availability. There were some initial issues resulting from confusion of the two separate water supplies that have subsequently been dealt with by colour coding the greywater supply lilac and utilising left hand threads on the reticulation.

Such technology is recognised to be a public health risk due to the difficulties encountered with differentiation of these non-potable water supplies from the potable supply. It is unlikely to have a widespread appeal in New Zealand until this issue has been resolved. It has been installed for two new 35 and 37 lot subdivisions, one in the Kumeu area north of Auckland, the other in Coromandel on the coast west of Whitianga (see the case study in Section 9.4). The Kumeu project enabled a reduction in the communal land area requirement for final effluent irrigation. The project in Coromandel was required under subdivisional consent to address the issue of water supply availability during the peak summer holiday period.

Ultrafiltration processes utilising membrane filters from the food industry are being trialled in conjunction with disinfection systems to reclaim water for discharge to sensitive environments, and for household re-use applications in Australia. This technology is available in New Zealand.

Greywater recycling for toilet flushing can be provided for individual households in a community situation via a three-stage treatment system that strains, then deodorises, then disinfects household bathroom and laundry wash waters. The resulting product is cloudy in appearance, but entirely suitable for recycling for toilet flushing. It is a New Zealand development, and is applicable for urban households where a saving on both water use and wastewater production is desired by homeowners. It can also be used for existing rural–residential cluster dwellings where reduction in communal land treatment area is desired.

Drip-line irrigation developments

Septic effluent drip irrigation is under trial in the US and in some areas of New Zealand. The septic tank effluent has to be highly filtered by an automatic filter system, with backwash cycling prior to drip-line application. The objective is to provide more effective distribution of primary effluent into aerobic topsoil layers to take advantage of the soil's treatment capacity.

Controlled-drip sub-surface drip-line systems provide a geotextile wick above a plastic strip to ensure that effluent disperses fully along the length of the drip line instead of concentrating at the drip emitters. The objective is to better use the soil system to treat and absorb effluent. This system has been developed in Australia and is available in New Zealand.

Innovations in integrated water wastewater services

There are a range of innovations under trial and investigation overseas as demonstration projects. Some of these are summarised in the box below.

References for: Innovations in integrated water and wastewater services

Craggs, R.J.; Tanner, C.C.; Sukias, J.P.S.; Davies-Colley, R.J. Dairy farm wastewater treatment by an advanced pond system (APS), pp. 105–111.

Etnier C. and B. Guterstam (eds), 1997. Ecological Engineering for Wastewater Treatment. 2nd Edition. Lewis Publishers. (Link to publisher)

Etnier C, Refsgaard K.1999. Economics of decentralised wastewater treatment: testing a model with a case study. Paper presented to the conference: Managing the Wastewater Resource – Ecological Engineering for Wastewater Treatment, 7–11 June 1999, Ås, Norway.

Kuczera G, Coombes P. 2001. A systems perspective of the urban water cycle: new insights, new opportunities. Stormwater Industry Association 2001 Regional Conference, Port Stevens, NSW.

Otterpohl R. 2000. Design of Highly Efficient Source Control Sanitation and Practical Experiences. EURO Summer School DESAR, Wageningen, The Netherlands.

Wild U, Kamp T, Lenz A, Heinz S, Pfadenhauer J. 2000. Cultivation of Typha spp. in constructed wetlands for peatland restoration. Ecological Engineering, 17(1): 49–54.

Appendix 6 On-site systems – key features

Note: All costs are indicative only, may vary from site to site, and are stated in 2002 dollars.

Appendix 7 System Matrix

Appendix 8 Examples of Decision Trees for Wastewater Systems

(a) Pit toilets

(Courtesy of Department of Conservation from: Standard of Practice for Backcountry Hut Toilets (draft)

(b) Septic tank systems

(Courtesy of Department of Conservation from: Standard of Practice for Backcountry Hut Toilets (draft)

Appendix 9 Example of protocol for conducting public meetings