Tuesday, January 25, 2011

Indigenous Biomass in underground water tanks.

What is indigenous biomass? Biomass has a few acceptions, one of the most simple ones is : "mass of living biological organisms", it also has a connotation from a renewable fuel source perspective. In any case our first definition encompasses this too. The indigenous component of the term comes from the definition: "Originating and living or occurring naturally in an area or environment." So basically we can say that it is life forms that occur naturally, and in the case of this topic, in underground water tanks.

Having defined the above we can discuss about how we can manage Indigenous Biomass to an advantage, as it can have very good or very bad effects on the quality of water.

Why is this question relevant?
It is a frequent question I get related to what happens in underground water tanks being related to appearance of biological matter in the tanks and how it affects the water quality. In addition to this we often get questions associated to the maintenance of the system, in relation to the previous phenomenon. I stress that if a system is properly and correctly designed, it should not require maintenance, this is the first point of a correct Environmental Sustainable Design, if it requires maintenance, it is not sustainable.

Beyond the specific design of a particular project, one obviously needs good components to achieve sustainable outcomes. So once again, we have to look at integral design considerations. In addition to this we have to look at the quality of the water that is going into the system, because no matter how fantastic is our design and the quality of the components, in terms of their functions if we put in water that is beyond the scope of the design we will not have the desired outcomes.

It is often heard and said, that where there is water there will be life. In fact it is not a coincidence that the first thing scientists look for in space exploration, searching for habitable environments, is the presence of water so that it may be able to sustain life.

We can start by saying that water, unless it is contained in sterile conditions, will invariably "generate" biomass. Keeping large amounts of water in sterile conditions is very difficult and not very cost effective. What happens then is a situation that we see very often, water, unless it managed correctly, will become stagnant.

Water as soon as precipitates from the sky, where it is normally free from biological matter, and touches the ground it immediately becomes subject to conditions that can be "good" or "bad" for it's quality. The words good or bad are purposefully subjective. 

We must first define what is good water quality, this is normally done, among other parameters by presence of Fecal Coliforms (FC), Coliforms, E Coli, pH (acidity), Heterotrophic Plate Count, Turbidity, Heavy Metals, BOD, COD, TN, TP, etc...

To be simple in our explanation we can say that water can be kept in two sorts of environments, one that is entropic or one that is negentropic. As entropy is associated with degradation, in this case of water, we should be looking to create a negentropic environment. I have addressed the subject of Negentropy from an ESD perspective in a previous blog post.

The important thing is that if the water enters a negentropic state or environments it becomes subject to a compounding effect that creates a vicious cycle if you wish.

There are things that are not "too" complicated and achieve several desired outcomes can be things like the following:
Keep water underground

Effects: Keeps water temperature low
Keeping water underground normally keeps water cool, unless it close to geothermal active area.

source: http://iopscience.iop.org/1748-9326/2/4/044001/fulltext
In the above graph we see how as we get to a depth of 6 meters underground, temperatures have a tendency towards about 9 degrees C. The largest change happens between 0 and 3 metres depth which is where it is most practical and cost effective to install underground tanks. This is will also important from a physical aspect that I will explain in more detail in the section I explain about capillarity.

From a chemical point of view the importance of temperature is relevant as the cooler the water, the higher the Dissolved Oxygen (DO) capacity that it has.

source: http://www.cotf.edu/ete/modules/waterq3/WQassess3f.html

The oxygen content is important because, the lower the DO, the higher the probability that anaerobic activity should occur, though paradoxically one could say that this an inevitable consequence anaerobic activity or digestion occurs once the dissolved oxygen has been consumed, which is a consequence of aerobic activity rather than anaerobic, however it can also be observed that aerobic digestion also reduces Biological Oxygen Demand (BOD),  which is something positive.

Aerobic digestion, is often associated to composting, which is a process that creates practically immediately usable by product without any undesirable by products, which is not the same situation with anaerobic digestion which creates sludge and methane. Recent and more modern process have made plants that use this process more efficiently, the methane, which is a green house gas, can be used for heating either to dry sludge or for power generation or even both, but the burning of the methane, produces carbon dioxide too. The management of sludge is also quite a complex process and there is an entire industry dedicated to it, in best cases when process it can be used as fertilizer, or worst case burned, creating a lot of pollution or buried and lost. Aerobic digestion in water treatment also serves to reduce BOD as well as pathogens and other desirable outcomes.

Why is all of this relevant to underground tanks? Very simply because all of these process can occur in underground tanks.

The very temperature also has an effect from a biological perspective on what types living matter can exist in water, in addition to this, the cooler the water the longer that water can remain in better conditions as biological metabolisms are directly affected by temperature, as such the colder the temperature the slower the reproductive cycle.

Effects: Keeps water dark
The effect of keeping water dark is very important, apart from the presence of light being associated with heat, in this case the darkness is important to protect the water from plants that perform photosynthesis. Though photosynthesis can normally considered something positive as it is an oxygen producing process, however this also implies that the plant metabolic process that also requires some measure of oxygen as the plant apart from to photosynthesising also performs cellular respiration, which consumes oxygen, instead of producing it. Aside from this a very common form of algae that may become present in water exposed to light is what is generally named Blue Green Algae or Cyanobacteria, this type of algae poses two main situations that are of interest, one is that it produces toxins which are know as Cyantoxins, which undoubtedly poison water. The other interesting aspects within their robustness is that they are also able to exist not only in aerobic conditions, but also anaerobic conditions, which then presents the problems we had mentioned in the previous point.

source: aims.gov.au
Source: gallery.usgs.gov
 The best thing then is to avoid light.

Provide high surface area to volume ratio
Providing a high surface area to volume ratio does mainly two interesting things.
Effects: More surface area for beneficial biomass
The more surface area one provides the more ability there is to form biofilm. Biofilm is a form of biomass. Biofilm necessarily exists attaching it self to surfaces, hence the more surface area we provide in a determined volume the better it is. If we have the presence of "good" biofilm.

Above is a photo of excavated modular tanks, that where taken out of the ground after 6 years. The tanks were excavated because within the scheme of the Australian Economic Stimulus Plan for schools, this school received funding to construct an additional building and as such relocated the position of the tanks. The case study for the original installation that was done in 2004 can be seen here. What is impressive about these tanks is that having been removed from the ground that they are in impeccable conditions.

What is important then is to explain why the presence of biofilm is good and beneficial for an underground tank system.
I have listed below 2 interesting and relevant points from the wikipedia article on biofilm:

  • Biofilms can also be harnessed for constructive purposes. For example, many sewage treatment plants include a treatment stage in which waste water passes over biofilms grown on filters, which extract and digest organic compounds. In such biofilms, bacteria are mainly responsible for removal of organic matter (BOD), while protozoa and rotifers are mainly responsible for removal of suspended solids (SS), including pathogens and other microorganisms. Slow sand filters rely on biofilm development in the same way to filter surface water from lake, spring or river sources for drinking purposes. What we regard as clean water is a waste material to these microcellular organisms since they are unable to extract any further nutrition from the purified water.
  • Biofilms can help eliminate petroleum oil from contaminated oceans or marine systems. The oil is eliminated by the hydrocarbon-degrading activities of microbial communities, in particular by a remarkable recently-discovered group of specialists, the so-called hydrocarbonoclastic bacteria (HCB).
Effect: Increased capillary action
Capillary action is present for several reasons in correctly designed underground tanks, because of several components that contribute to it.
Sand: Sand has capillary action that occurs because of the granularity of sand. A tank that is correctly designed should be surrounded by an "envelope" of sand. The sand in this case also provides a situation that has a filtration effect that is not only mechanical and physical, but also biochemical as stated from the effect the biofilm has on the sand.
Geotextile: Geotextile as a fabric has capillary action. Below is a photo that shows this effect. A geotextile is a fabric that is made of plastic polymers, that for practical effects, does not biodegrade with time, especially if it is being kept underground. Geotextile should cover the modular tanks so that the sand surrounding the tanks does not enter the tank. In this case it not only serves as the purpose to provide capillary action but also as a separation and filter media.
source: http://www.sciencebuddies.org/science-fair-projects/project_ideas/PlantBio_p033.shtml
Tank components: Some modular tanks, have flat sides, these flat sides when placed together also creates capillary action. The closer the plates are together, the more pronounced this effect is.
source: http://webapps.lsa.umich.edu/physics/demolab/controls/imagedemobg.aspx?picid=1102

Capillary action has several effects the main one is that it moves water. As capillary action moves the water upwards, against the force of gravity, it eventually reaches a stage where it can not go up any more, at the same time it has more water molecules below it that are pushing up, as they are subject to the same forces of capillarity, however the difference with the situation of the tubes shown in the above photo, is that water in the sand, in the geotextile or between the modules, can "fall off" the tube, or be subject to a situation where as the cooler water from the bottom of the tank which is more dense, enters an area where the water is warmer and hence less dense, this cooler denser water will naturally descend again, until it gets to it's level of homeostasis, and again be subject to the effect of capillary action. This constant movement of water, by definition eliminates the possibility of the water stagnating. In association with this, as water would reach the water surface, it will also be subject to air and as such become aerated, once more increasing the Dissolved Oxygen level.

Comparisons with different types of underground tanks

Having said the above we can say we have found a situation where were create practically ideal conditions for the conservation or storing of water. So one could say that as long as one puts water underground then it should be acceptable. Not so much so, traditionally one of the most common types of underground water storage tanks have been cisterns made of concrete, these can be strong, but have the observation that the have an extremely low surface area to volume ratio, as such, unless external power consuming agitation, aeration devices or chemicals are used the water will go stagnant. The same is true of similar plastic or fibreglass cisterns. Recently there have also been a number systems that use "half pipes" providing void volumes, these have a larger footprint as they cannot be stacked, and are infilled between the half pipe rows with crushed rock or similar, this we could say is better that a traditional concrete cistern, as they are comparatively providing a slightly higher surface area to volume ratio.

As such having made the above analysis, we can see that to have indigenous biomass that is aerobic and beneficial for the water quality we also have to provide a good environment for it to exist. If this is done it can even be said that the quality of water while it remains in such a type of environment will improve with time.

Friday, January 14, 2011

Negentropy from an ESD perspective and its imperative

This topic is a bit extensive to put and completely justify in a blog post, what I would like to do however is to make an introduction into this as I believe that this aspect a critical, fundamental and core to what is both a central to the source and effect of Environmentally Sustainable Design.

Of the literature that currently exists on this topic, most of it revolves around the periphery of how to achieve Sustainable Design, mainly basing it on concepts of renewable resources, both of material and energy, as well as delving into the aspects related to the environmental impact, it should not have.

From a historical perspective there has been some amount written on this topic, a search on Google for "entropy sustainability" return several papers written on the topic, however what is interesting to note is that most of these make reference to the Bruntland Report published in 1987 and make a start from there, some assuming the definitions of sustainability therein described, which was commissioned by the UN. After some papers that appear at the beginning of the 1990s, the topic largely disappears, except for some sporadic papers and constant contributions of Prof. Timothy Gutowski of MIT (Publications).

What I have found though, except those that directly address the topic, is that most of them miss the central base point of how sustainability is achieved. Those that directly address the topic, normally go as far as establishing the nexus between the aspect of Thermodynamics or Entropy and Sustainability, though they do not really elaborate on how to go about designing sustainably with this in mind.

As this is not an academic paper, and my idea is to provide practical and viable contributions to society, not that academic papers do not also do that, but they have another focus I will and give a more practical focus to what is being presented. Another observation is that for everyday purposes, I believe that concepts have to be synthesised so that they are easier understood, as such I prefer to use the word "Negentropy" meaning the inverse or in opposition to what is entropy.

So to summarise, in my view, this is achieved be designing systems that are, or tend towards, establishing Negentropy, from the acception of ESD.

To be able to elaborate on this it is necessary to trace back one's steps though and start with explaining what is Entropy, which is associated with the Second Law of Thermodynamics as a corollary.

To explain entropy succinctly is not simple, this is my attempt to do so in lay man's terms and how I connect it to ESD: Entropy is manifested when heat flows from hot to cold regions, this heat is molecular agitation and in the measure that we have more agitation there is more disorder in our systems and as such degradation.  

One of the most common examples of entropy is ice melting in a warm room.
source: wikipedia
How do we apply this concept them to ESD? Well, an easy way to do this is in the concept of an urban environment, in a building that uses air conditioning. It is very good as it shows how entropy can be accelerated and what is the alternative as a solution invoking sound ESD principles.

A definition of air conditioning that can be used is: is the removal of heat from indoor air for thermal comfort. Now comes an interesting question where does this heat that was removed go to? Well outside obviously, this hot air, summed to other aspects such as the albedo of reflecting surfaces in urban landscapes, provide a feedback loop that has the effect increasing the temperature difference, making it ever hotter outside due to the increased demand on the air conditioning system to remove "heat from indoor", as the environment indoor is necessarily affected by the outside temperature. This effect is called the Urban Heat Island.

So what can be done about this? How can we introduce the concept of Negentropy to create a sustainable design in this environment which can be said is a very typical one where there is human population.

Plants or Flora as Negentropic elements
(please not that the intent of this is to be as illustrative as possible, to go into to details such as excepting archaea, or using terms like autotrophs and heterotrophs extensively, might defeat the purpose of reaching a wider audience.)
Vegetation can be considered as negentropic for several reasons. From the basis of the description of entropy, plants we could say have an effect that is "opposite" of entropy. Among the reasons plants grow we can find, for our purposes, two main ones which would be photosynthesis and the requirement of "heat". When referring to heat we mainly want to imply 2 or 3 conditions. Heat refers to a manifestation of molecular movement, hence one could theoretically say that anything over 0 degrees Kelvin, would be "heat", this is any the formal definition from a physics or chemical perspective. In colloquial terms though heat is a relative term, heat or something being hot could be considered above what has been defined as thermal comfort which is 21 deg C or 70 deg F, and then again it could be whatever anyone wants to define it.

Autotrophs, life forms that "create their own food", need heat to metabolise, this heat is transformed into organic compounds, what today has fashionably been called "carbon sunk" if you wish. This means that in a closed system heat is for practical effects being "absorbed" in an endothermic reaction. This constitutes, we could say and negentropic situation.  

In the case of photosythesis, implying phototrophs, light and in this case we would mean sunlight, we also have a situation where light energy is being transformed again organic compounds. The presence of light is for our purposes associated with the presence of heat, in the measure that heat can be absorbed, photosynthesised, metabolised, is once more for practical effects a negentropic situation.

So as we have elaborated a bit on this basically what are we aiming for here? We have identified 2 aspects that we can work with, heat and light, both of these are forms of energy or E.

Albert Einstein put very well and succinctly quite a few years ago in his formula E=mc². When I was at high school and even later, when I was study to get my degree in engineering, it was a concept a bit difficult to grasp saying that if I have, matter (m) and make it travel at the speed of light (c) squared, then I end up with energy (E). What if we look at it another way, energy can become matter, which is what happens, for our simple purposes, in negentropy. The energy that is heat, is "sunk" in to the carbon structures that these autotrophs metabolize.  

Going back to our air conditioning example, if we were to have plants surrounding the building, on the sides and on top as well as inside, we could do substantially to reduce then the entropy as the plants will be having several effects to break the feedback loop of ever heating the environment.

Water quality
This is another one of the cases that I find interesting. Water is tremendously complex, interestingly enough temperature is not given enough importance as characteristic of water quality, some people do however. The presence of dissolved oxygen (DO) is obviously a critical aspect of water quality, this goes down in the measure that we have more BOD or COD, but also temperature, we could mention some other aspects, but that would possibly be too much detail for the purpose of illustrating a point. "Coincidentally" all of these points are interdependent and related. However the point here is that in the measure that water enters an entropic cycle, where it is heated, it is degraded, remember heat is associated with molecular disorder, it also becomes a more suitable environment for anaerobic lifeforms, which can only further degrade the quality of water, further increasing the BOD and reducing the DO.

What is to be done then? Well water has to be given conditions where it can exist in a negentropic situation. How is that done? Well that is another point that depends on every situation in a different manner.

There are many more aspects that could be discussed that would have relation to how negentropy can positively affect ESD. I look forward to receiving any observations, corrections or questions on this topic.

More reading and references:
Preliminary Thoughts on the Application of Thermodynamics to the Development of Sustainability 
Criteria Entropy and Its Implications for Sustainability
Economics,  entropy  and  sustainability
Entropy and Energy: Toward a Definition of Physical Sustainability

Wednesday, January 12, 2011

Some philosophy and culture behind ESD

When I first began working in this industry, what I most did was learning. Everything I did was new, my background was not of one related to the environment, and though I knew quite a bit of related to water management, mainly because on a ship you often find yourself with water rationing and restrictions and the main source of water being desalination, this was definitely not the sort of water management I was used to.

Among the things that struck me was how this was in fact a very young field, from every aspect. Even in my blog header I put " ESD is a relatively new concept in the human conscience.", I wrote that when I first set up the blog and I was thinking to myself: "what do I put here??". I had since thought of changing that to: making a "new" concept in the "western" human conscience... this is possibly more accurate.

Western cultures were more centred on themselves rather than the environment, one talks of an anthropocentric world, true, however but this was supposed to have begun in the renaissance, what of the theocentric world? Well in my opinion, this was also a previous version of a anthropocentric view, where man again placed God at the centre of the universe, and remember that in the Christian tradition man was made in "our image (God's), in our likeness," and then goes on to say "so that they may rule over the fish in the sea and the birds in the sky, over the livestock and all the wild animals, and over all the creatures that move along the ground." (Genesis 1:26-27) of God, thus again he puts himself in the centre of the world. Well what has religion and the bible got to do with ESD? Well at the same time, not much and quite a bit. I am not making a religious discussion of this, but rather a cultural one, and this is certainly relevant, because it is the culture that we live in, that is obviously affected and affects the environment.

Why did I suggest the "western" aspect, why because the bible is, we could say for present practical purposes a western document, though more eastern in its origin, and it was the judeo-christian tradition that affected the western culture and for the better part of several centuries, and was the culture that came to dominate the planet, in more ways than one. Now that is obviously changing.

What of other cultures, may be eastern ones, or southern ones, to give or maybe invent some names. I would say that in these cases we see a situation where maybe possibly that was a "better" cohabitation with the environment, however I would argue that this was not necessarily purposeful. One of the great myths that always frustrates me is that how "original inhabitants" where supposed to have lived in closer harmony with nature, however around the world there are innumerable cases of mass extinction once humans arrive, in New Zealand for example with large flightless birds and marsupials, with similar situations in Australia, in Easter Island or Rapa Nui with flora being wiped out, to name a few cases. I would say then, yes, it is something new in the human conscience. No one gets "off the hook", for every story of how "original inhabitants" took care of the land, we can name several of how they did not. The idea is not to point fingers though, we are all universally to blame.

I find, and cannot but think, that again through what we see today, is not really an expression of that we are in fact prioritizing the environment, for the sake of the environment, once again we are doing it for ourselves, for the self preservation of the human species.

Another thing that I invariably find wherever I travel around the world, no matter how fantastic the solutions I propose are for the environment, if they are not economically viable, then they are more than quickly discarded.

At the end of the day, and Environmentally Sustainable Design, still has to be more cost effective than a "traditional" one or it has no place the environment, only very few exceptions exist to this situation, for example tax or government incentives, and even then they are related to economics once again.

Wednesday, January 5, 2011

The Energy Cost of Gravity in Desalination

Another aspect that I find people tend to "forget" with costs of desalination related to power consumption, is the fact that this water has to be pumped up-hill. This is an unavoidable "cost", there is no way around this if you plan to use desalination, and desalination operation are almost invariable located at sea level. Forget about the immense amount of power required to generate the pressure to push the saline water through the membranes.

Let's take a look at the case of Los Angeles as a possible example. This is a very simple back of the envelope calculation considering that the whole of Los Angeles water supply would to be done through desalinated water, now I know that won't be the case, normally this additional sort of infrastructure is supplementary, remember this is to illustrate a point.

Using the data provided by Los Angeles Department of Power and Water (LADWP) it sold 193 billions of gallons of water to it's consumer in the 2009-2010 fiscal year. Taking the elevation of Los Angeles at 71 m (233 ft) location of the City Hall, as an approximate average for this calculation, calculating just the potential energy in joules required to simply elevate vertically this water, not considering any horizontal transportation or mechanical inefficiencies of pumps, etc... it requires 1.39 TJoules, this corresponds to 16.2 Mega Watts per day. Additionally this does not even consider providing any extra head or mains pressure...

Have in mind additionally that Los Angeles supplies itself with 70% non renewable power sources (http://www.ladwp.com/ladwp/cms/ladwp000509.jsp) which are only carbon emission producing.

Now this may seem a lot, or maybe not very much, if one considers the cost of which a KWatt/h is sold at. My idea is not evaluate if this is expensive or not, it is to illustrate that there is energy to be spent on something that can be avoided. As a percentage of the total power consumption of Los Angeles it might seem insignificant, however remember this is a pure mathematical physics model.

My simple calculations can be seen here: 

No matter how energy efficient you become, there is no way to avoid the energy cost of simple gravity.