Federal-Provincial Assessment Review Panel for the Halifax-Dartmouth Wastewater Management System Volume 7, 26 March 1993 (Halifax: Halifax Harbour Cleanup Inc. 1994).
Herb Campbell [Engineer, with expertise in OFS technology, he was hired by HHCI]: “I am quite pleased to have the opportunity to spend a little bit of time and try and put the Oil From Sludge technology into perspective, perhaps for those people that have not had the opportunity to really understand where it fits in, and hopefully also to allay some of the misunderstandings that appear to be associated with the technology.i […] [W]e all know that sludge management is an expensive procedure. We have done studies, we know that in many plants, depending upon the size, depending upon the technologies, but it is quite easy to have sludge management account for up to 50 per cent of the total treatment cost, both in terms of capital cost and in operational cost. The other thing is that, whether we like it or not, sludge is very visible. […] So the public, quite rightly, are concerned both about the aesthetics and the health effects associated with sludge management options.ii […] But when we look at sludge management, and I think this is very important, and it is something that we have to consider all the time: it is not a question of yes or no. […] So really, the question become how; how do we do this? […] If you want to get to the nitty gritty, the options fall into three categories: landfill, some kind of land utilization and some kind of thermal processing.iii […] Oil from Sludge. Well, the key to Oil from Sludge really is the recycling of energy within the system, and again, let me stress what we are talking about is what happens within this box, okay? [Dewatering, and drying].iv
We also generate two by-products. Those are in effect fuels, because the water has already gone. Those are put into a furnace, an energy generator, where they are combusted and the heat that is released goes back to dry the sludge. So the key to this triangle is where everything is linked.v
[…] The Oil From Sludge process basically consists of dry sludge heated to 450 degrees Celsius without oxygen at atmospheric pressure […] you basically cook it and it is thermally converted to a product for sale, which is oil, and by-products for internal reuse. So, the product for sale is liquid hydrocarbons or an oil, and what we are keying in right now, that holds a great deal of promise and has people at NRC and ourselves quite excited is the application in the asphalt industry.vi
Rod Giffen, Purcell’s Cove: I understand there was a delay in the approval because of emission concerns, as Ontario has banned incineration. One of the criteria was that emissions would have to be chemically treated, which is one of the standards Ontario was moving to for incineration, I believe.vii
Herb Campbell: No, I would like to clarify a couple of things here. In Ontario, the incineration of municipal solid waste, household garbage, has been temporarily banned, and let us not confuse the issue between municipal solid waste and sludge incineration, because they are not the same. There are very great differences. In Ontario 75 per cent of the sludge that is produced is, in fact, incinerated.viii
***
Patricia Lane, et al. v.7 p. 99.
Lane: The purpose of the Alternative Technologies report is to show that there are viable possibilities, not to design the total system. This is the Proponent’s responsibility, of course. The project started claiming that this was a large-scale cleanup of Halifax Harbour. More recently, they have said it is a first step. […] It also is not a very good first step. In the Alternative Technologies we are giving a range of viable options and focusing on engineered wetlands in Mainland South.ix
Because of the large tunnelling costs for just a few per cent of the sewage to take it over to McNabs Island, the goal is to show that engineered wetlands are viable, that it gives a better level of treatment, more environmental protection at much less cost, and what we have produced is a preliminary conceptual design. On Monday night HHCI had Mr. Sherwood Reed talk on engineered wetlands and he had reviewed our report. And I think it is critical to remember that he agreed with us that engineered wetlands are viable; that, in general, they are a very cost-effective alternative and that they are very good at protecting the environment.x
He agreed with our design in terms of the BODs, suspended solids and coliforms. He disagreed whether or not it was large enough for nutrient treatment. But it was still, even with less nutrient removal than what we claim to be able to obtain – it would still be vastly superior to what the effluent will be from the primary treatment plant where they are claiming on 10 per cent removal of nitrogen and 20 per cent removal of phosphorus. Furthermore, we do believe our design is correct, but even if it was too small, the major points we have attempted to prove I think were confirmed very much by Mr. Reed. Today out wetland’s design, Dr. Lakshman from Saskatoon, is with us […] [he] has recently designed a wetland to treat large amounts of water, wastewater; in fact, larger than the whole metropolitan system on the Nile Delta – and also this water is more polluted – at a very low cost: $10 million overall capital and operating cost for five years.
This project was designed for the global environmental facility funded by UNEP, UNDP and The World Bank, and it received incredible scrutiny by over a hundred reviewers of all kinds of technical disciplines but also several world-class wetland designers, and it was judged the best project in the GES portfolio, I think largely because of Dr. Laksham’s work on the design.xi
Dr. Gurunathan Lakshman: Since the industrial revolution we have been blessed with a number of technologies that make our lives very happy and joyful. At that same time we have also been blessed with a number of problems. One of the perennial problems we have been experiencing is the treatment and utilization of waste and wastewaters. Over the decades, probably for the last 50 to 60 years, we have been using traditional technologies based on well-known physical/chemical reactions and knowledge to treat wastewaters and produce water that can meet the standards. […]
Is it essential to produce a technology that costs you millions of dollars to treat the wastewater from a small community of a hundred thousand, two hundred thousand or three hundred thousand people. We can send men to the moon; we can do genetic engineering; but don’t have an onus to develop technology that is affordable, that is efficient, effective, ecologically acceptable and aesthetic. This is the main problem. And in North America this is exactly the reason why we have been looking at some innovative ways of treating wastewaters and sewage and also developing methods of utilizing the wastewaters.
[…] This had been asked about 30 years ago; the engineered wetland treatment system has evolved from a concern of this kind of need and a lot of research has been done in a number of disciplines, including physics, chemistry, soil microbiology, plant physiology. Plant metabolism, ecology and mathematical modelling of the systems.xii […]
[T]here are three very important ingredients operating in an engineered wetland treatment system:
1. The first one is a physical chemical process. These are the processes responsible for precipitation, sedimentation, absorption, adsorption, and a number of things that can happen[.]
2. The second important thing is the microbial metabolism. There is a tremendous amount of microbial flora that exists in the natural system […] sewage contains the nutrients that are required for the microbial flora to flourish and to do their job.
3. The third one is the plant uptake. It is an extremely important mechanism. Some of the aquatic plants like bulrushes, cattails, water hyacinth, phragmite, and a number of duckweed, for example, have this innate ability to gobble up pollutants, nutrients, heavy metals, toxic chemicals, simply because they are not evolved to the extent – there are no mechanism within the plant system to tell them this malignant molecule is going to kill you, don’t take it, they gobble up everything, as long as they see the phosphorus and nitrogen that are necessary for their metabolism, they gobble up a number of nutrients, a number of pollutants.xiii
So if you combine the three very important processes that we know quite a bit into an engineered system and design a system that can take the effluent and have a retention time so the wastewater can access all these mechanisms and then out comes a treated wastewater. […] We understand the mechanisms, most of the mechanisms, we can put them in a design and design a system that conforms to the site-specific problems and overcomes the site-specific problems. […] Then what we do is look at the symbiotic relationship between the bacteria and the plant, how do they behave when you put in the wastewaters into the systems? We can harvest biomass from an engineered wetland treatment system. As you harvest, you are exporting a lot of materials out. Contrary to a lot of engineered wetland treatment system designers we have shown and a number of other people have shown that you can use very effectively the biomass mechanism to remove nutrients from the wastewater.xiv
[…]
So the entire treatment system is a dynamic system. So when you are designing an engineered wetland system, you have to take into account not only the efficiency now, but ten years from now, 15 years from now, when the plant systems grow, and I how does the plant system in an engineered wetlands treatment system behave. And if you want to compare the effectiveness of the engineered wetland treatment system with a conventional – I am not even talking with primary, I am talking about one stage higher, secondary treatment system, BOD removal using the conventional secondary treatment system is 80 percent, if you can do that, and engineered wetland treatment system is more than 98 per cent.xv […] If you want to reduce the pathogenic bacteria, the fecal coliform. Streptococci, and a number of different kinds of viruses in sewage […] It is possible to remove more than 99.9 per cent of the pathogenic bacteria in the engineered wetland treatment system without using any chlorination whatsoever.xvi
Then removal of priority pollutants. A number of systems – this is just an experimental laboratory based pilot scale of operation and it shows the benzene, biphenyl, ethylbeneze, naphthalene and bromoform removed by up to 81 per cent, 96 per cent, 99 per cent in about 24 hours.
This gives you an idea of the flexibility and plasticity of the entire system, the potential that exists in engineered wetland treatment systems to do a number of things. Whether your sewage contains these toxic chemicals or not is another question. […] And again, it gives yu an ideas of the removal of heavy metals by these systems, including mercury, arsenic, silver, strontium, copper and zinc, et cetera. […] Now there are a number of innovative ways of making the engineered wetland treatment systems perform at a very high level. […] You can engineer the way you want, as long as you understand the processes that are responsible for the degradation of the pollutants, and as long as you understand the limitations, you can do that. […] You can use a number of plants there to do the job. Look at the density of this plant here [image]. They are enormously growing plants, and these plants are not sitting there gobbling up all the nutrients. They photosynthesize; they produce photosynthetic oxygen. When they do that an enormous amount of oxygen that is produced from the leaves here travels down that tube of the stem here into the root system there, they get the oxygen so they can degrade the pollutants and therefore you BOD reduction and ammonia reduction, et cetera.xvii
In a conventional physical chemical treatment system all the processes that are responsible for the sedimentation, whatever removal, BOD removal, they are all sequential. In an engineered wetland treatment it is concurrent. All the processes are working everywhere at the same time. […] When that happens it is easy to scale it up. All you have to do is build one more like it adjacent to it if the population grows up. Then it promotes a broad spectrum treatment. It can remove nutrients, heavy metals, toxic chemicals and bacteria and virus.xviii
Engineered wetlands convert wastewaters into tertiary treated water, that is the resource material. That can be used in horticulture, irrigation or industrial use. You can harvest the biomass coming from the engineered wetland treatment systems and then you can produce a number of marketable products, depending upon the type of effluent you are treating. If you are treating effluents with high heavy metals, obviously you cannot use as animal feed; you can use it for thermal insulation and a few other – methane production or ethanol production. But the whole schematic here is the quintessence of a sustainable development. So an engineered wetlands system is an innovative technology sitting at the centre of a concept for sustainable development.xix
But the main point I want to make is an engineered wetland treatment concept is no more a concept, no more an untested technology. It is a fully grown, highly evolved, highly systemic technology that can be out into a turnkey operation.xx
[…]
Mr. Fudge: Madam Chair, I would like to ask a brief question, a point of clarification. Regardless of the size whether it is twenty (20) or fifty (50) or whatever and I want to get this clarification: the “as proposed,” is a storage – a winter storage facility? Is that part of the sixteen (16) or the twenty (20) or whatever or would that be additional if that were required?
Dr. Laksham: There is no winter storage at all. It is a continuous flow year round operation. It switches from the surface flow into subsurface flow during winter time and switches back to surface flow. […] It is a deep system then winter time – when the summer time – spring, summer and fall until the freezing occurs, the sewage discharges –open water surface operation goes to the system.
As soon as the freezing sets in when the ice builds up then you turn this surface discharge off and turn on the subsurface so it begins to operate under the surface – under the ice layer – below the ice layer because the frost penetration in Halifax is less than – I think it is about thirty (30) centimetres or less in soil. It could be a little deeper in gravel. So we are making exact calculations on the depths but it is definitely a year round operation.
[…]
Mr. Rob Grant [HHCI]: Madam Chair, may I – may I just ask that Dr. Lakshman file to the Panel his résumé and –
The Chairperson: It is already there.
Mr. Rob Grant: Okay well – and – […] I was wondering as well if it would list the Engineered Wetlands designs that he [Lakshman] has been involved in?xxi
David Wimberly: I know that an engineered wetland is currently in operation here in the Metro area to treat a runoff from the airport and I know that another one is currently under construction to treat the leachate from the Sackville landfill because the chemical processes there are inadequate for the process so they are building an engineered wetland. My question is how far can we extend this technology? […] I know that if you take the dry weight per day of all the sludge from the Metro area or, say, just from the areas going in the arbour right now, it is only five point five (5.5) tonnes per day and that is about a truck and a half full.
Couldn’t it be – even if you build on McNabs Island, as absurd as it is, wouldn’t it be a heck of a lot cheaper and a better level of treatment for that to take that up and put that into a wetland somewhere rather than building this OFS technology and these sludge and sewage from all of the County and all of Bedford right now is only four point five (4.5) dry tonnes per day – that is the estimate from HHCI – and couldn’t a similar thing be done then as an alternative to some of the other things?
[…] The next question would be: what biological systems do you envision might be suitable for the rest of Metro based around the wetlands idea? Are there other places it might be suitable and – such as the – such as something for the industrial parks for instance as an integral part of designing and building an industrial par[k]? Wouldn’t it be more sensible to make a little wetland for that area rather than trying to put in this massive tunnelling and all this extra cost as a way of looking at how do you make this sustainable development from the design of the actual system that you put in? And the final thing is, I would like through the Panel to ask if they could ask HHCI what “size”, in other words, what design, process and price they would need on McNabs to accomplish the efficiency of the engineered wetlands whether we are talking about the figures that we got from Sherwood Reed or from Mr. Lakshman?xxii
In other words – and as a – off of that, what kind of nitrogen and potassium removal rates do we really need here because we are holding up the wetlands to a different standard than we are holding up the HHCI and we are holding the wetlands up to something that is near perfect by treatment standards as opposed to something that they admit if you get an effluent from theirs, you are going to get sick otherwise you are going to have to treat it. It has many more problems.xxiii
Dr. Palczynski: I would like to mention that I am a P. Lane and Associates employee. I was a team member who has been commissioned by the Metro Coalition for Harbour Cleanup to conduct a study on alternative technologies. Following the client’s specific request, the proposed alternative wastewater treatment technologies are based on natural processes with a substantial biological component. This presentation is based on the report which was developed for the client.
A constructed wetland and advanced systems – each for small, medium and large treatment capacity plants have been proposed. The wetland technology has already been discussed and the other technologies considered include rotating biological contractors, cyclic activated sludge system and multi-storey treatment facilities. All of these three methods are proven with – technologies with a good record of performance. Each alternative has its own merits and demerits but all provide advanced, at least secondary, level of treatment. We believe that the choice of treatment method should be based on – not only treatment cost but also system efficiency, volume of sewage to be treated, plant location, collection requirements and auxiliary services associated with treatment plant operation. Considering the worldwide tendency to provide the – in providing secondary treatment for marine discharges, it is fully appropriate to examine advanced technologies. […] A Rotating Biological Contactor wastewater treatment technology can be utilized in any municipal or industrial application where the wastewater polluting components are amenable to biological oxidation. The commercial use of rotating biological contactors began in Europe over two (2) decades ago. Since the first installations in North America in the early seventies, this wastewater treatment process has gained wide acceptance and has been applied successfully in hundreds of installations.xxiv
Functioning of the wetland:
The basic component of the facilities is the honeycombed or corrugated disk arranged in series which give physical support for attached microbial cultures. […] When the disk is submerged, it is exposed to wastewater and, as rotation progresses, to the air. Fixed microbial growth biomass is retained in the reactor. A biological growth of biomass is continuous with each rotation of the shaft. Some of the wastewater drains over the biomass back to the source. This process permits a high exchange rate between the atmospheric air and the wastewater. […] The actual efficiency of RBC is at the rate of (90) to ninety-five (95) per cent in removing pollutants. Some physical pretreatment like screen may be needed prior to the application of RBCs. The modular configuration makes it easy to select best sizes of the equipment by number of units.
Summarizing, the RBC offers the following benefits: low power requirements, low construction and installation costs, easily installed under any hydraulic gradient with a minimum head loss, eliminate the need for operator control of oxygen and solids return, reduced chemical and electrical needs which minimize operating costs and treatment and flexibility with wastewater flow path variations. This system could be considered for the Halifax Mainland South as an alternative to engineering wetlands. If installed, it would eliminate the need for tunnelling to Halifax Peninsula.
Next alternative is Cyclic Activated Sludge System [CASS] which is called also Sequencing Batch Reactor [SBR]. This is an aerobic biological process which can be used to treat many types of wastes. […] The process is versatile, flexible and efficient. An effluent of any desired quality can be produced by varying the process parameters. The cyclic activated sludge system technology has been developed to achieve better sewage treatment than in conventional activated sludge facilities. This technology incorporates sequencing batch reactor activated sludge processing using sequenced periods of aeration and non-aeration. This permits the use of a single vessel to accomplish biological degradation reactions and solids/liquid separation, the latter being necessary to produce a treated effluent.xxv
[…]
The general advantages of CASS [Cyclic Activated Sludge System] are as follows:
- Low capital cost.
- Produces a high quality effluent and well stabilized sludge.
- Requires minimal operator attention through automatic operation.
- Eliminates the need for separate load equalization.
- Eliminates secondary clarifiers and major return sludge pumping facilities.
- Utilizes less mechanical and process equipment than conventional activated sludge systems.
- Requires minimal land area.
- Exhibits superior sludge bulking control.
- Provides for energy optimization through biological denitrification if required.
- Amendable to simple modular construction.xxvi
A multi-storey sewage treatment plant would be recommended for the regional sewage treatment plant for the Halifax-Dartmouth area. It would provide the following benefits:
- The system offers advanced secondary treatment assuring adequate effluent quality specifications.
- The facility should occupy 40 per cent less area than similar treatment capacity conventional sewage treatment plant. This would make more sites available for the location of the plant.
- Advanced hydraulic systems would stimulate development of advanced design skills for the local consulting firms.
- Project expertise could be marketed to other cities in U.S.A. and Canada.xxvii
Concluding my presentation, I would like to emphasize that we have not conducted extensive studies of all established and emerging technologies. The purpose of this project was to show that, depending on circumstances, such as stricter effluent quality standards, area limitations and volume of wastewater, appropriate technologies are available. […] The Metro Coalition for Harbour Cleanup could be contact[ed] for this report. Thank you for your attention.xxviii
