ICA to the WWTP

The ARC Advisory Group recognizes the water and wastewater industry as one of the greatest opportunities for automation and control businesses over the next 20 years. Developed countries will require significant investment to improve already aging and outdated systems. Emerging economies and developing countries are also expected to continue investing in new infrastructure to meet the needs of a growing population and increased industrial activity.

Large commercial production industries are able to invest significant amounts in advanced, complete automation and control solutions with properly trained individuals. However, there is a divide between what the wastewater industry, particularly in the developing world, is willing to invest in both education and hardware, and what the current automation industry can provide for this price. Smaller treatment facilities often implement the cheapest solution that can still implement basic control strategies with the required human intervention. Advanced techniques for simulation, modeling and analysis are often not considered outside of research institutions due to the higher cost of hardware and software, and the required training.

Instrumentation, control and automation (ICA) in wastewater treatment plants (WWTP) is becomingly increasingly complex as the plants and process analysis techniques become more advanced. Online nutrient and other advanced sensor technologies are providing operators with large amounts of data that can allow for many improvements within the system and help operators manage the advanced, and often sensitive, processes. ICA has already been demonstrated to increase biological nutrient removal capacity by up to 30% today, while furthering the understanding of mechanisms involved for future improvement.

Despite the availability of cheap computing power, advanced and cheap sensor technologies, universal communication systems and greater usage of process systems techniques in other industries, ICA is still considered a costly addition to the initial design of a wastewater treatment plant, with many of the advanced control systems and sensors still considered to be too expensive. Training operators to use a specific commercial system is also expensive for smaller treatment facilities, and the trained individuals are only able to use the specific software provided. Even then appropriate data management tools are not properly available and restrict efficient use of sensors and analyzers for process control.

Availability of an economic, open and universal control and monitoring system would be especially useful in small, decentralized plants often found in remote rural areas. The open nature of the system would allow for easy access to knowledge, so that problems could be quickly fixed on-site without requiring expert assistance.

In the past few years there has been increasing interest in producing open-source automation systems for smaller tasks. Research has already been conducted into using the Raspberry Pi to directly control some basic tasks on an example water treatment facility. This research showed the possibility of using such a device to directly control sensors and controllers used in an industrial setting where stringent requirements must be met.

Accuracy tests conducted in a laboratory on the Arduino UNO have shown that synchrony across channels is accurate and scaling up the number of channels does not affect accuracy.

The Arduino has already been modified to allow for access to industrial systems. The Controllino is an Arduino standard and Arduino software compatible device that conforms to EN61010-1, EN61010-2-201 and EN61131-2 standards and allows for 35mm top hat rail mounting. A Kickstarter crowdfunding campaign to finance the initial production and marketing of the device attracted 191 supporters and successfully raised over $65,000 US, showing that there is an interest in such a device from the general public.

Could existing devices such as the Raspberry Pi Single Board Computer and the range of Arduino microcontrollers be combined into an open-source automation system with the stability, safety and security required for a full-scale wastewater treatment plant?

If this idea seems too far-fetched how about opening up such a system to the developing world, where more and smaller water and wastewater treatment plants are required? Of course, most of the work in developing countries is focusing on reliable and clean water with a minimum of technical equipment, which can break and needs maintenance by knowledgable technicians. But, what if the technical equipment can be programmed, fixed, operated on and controlled by anyone with access to the internet and the multitudes of forums and tutorials on programming and wiring such equipment? What if all that is needed is a cheap mobile phone to control and operate the plant? Any problem can be answered by the hundreds of thousands of enthusiasts online (The arduino.cc forum alone has nearly 400, 000 users looking to answer and ask questions), always willing to offer help and advice on the technical hurdles met by others willing to learn.

between
There must be somewhere inbetween

Maybe I am living in a dream world where developing countries and rural communities can have access to the more advanced systems for treating water and wastewater. Systems that require proper instrumentation and automation that is, in its current state, simply too complex and expensive for something as unprofitable as our waste and its effect on the environment.

 

Treatment or Recovery

There has been a trend in recent years for renaming some standard terms in the wastewater industry. Wastewater Treatment Plants (WWTP) are now being increasingly called Wastewater Recovery Plants (WWRP) and wastewater sludge should be referred to as biosolids for example. Some wish to actually change the name of wastewater itself!

So why is this happening?

Well, the most interesting components in typical municipal wastewater (we will keep calling it that for now) are the organics, which we will measure using the term chemical oxygen demand (COD) or how much oxygen is needed to remove them, ammonium and phosphate. We want to prevent these components from getting into our rivers and streams. But if instead of just looking at how to get rid of them, we look at how we might be able to extract and use them, we start to see how the term recovery can be used instead of just treatment.

So why are these components worth recovering?

The COD can straight away be converted into useable energy as biogas and ammonium and phosphate are important for fertilizers.

A term that was exciting a few years ago but seems to have dropped off most peoples radar at the same time they forgot about the whole ‘peak oil’ thing was ‘peak phosphorus’.

Looking at the above graph it is interesting to see that although there is a downward trend in searches for ‘peak phosphorus’, the large peaks in interest were followed by chunks of noone searching in the first few years after 2004 while more recently there seems to be a more sustained albeit lower interest.

I hope that this means there are still people keeping an eye on the ‘disappearing nutrient’. In the wastewater industry there are definitely people looking at all sorts of ways of recovering the phosphorus we are flushing down our toilets. Things like ion exchangers, membranes, electrochemistry and algae are all being investigated as possible methods for recovery.

I personally like the idea of capturing the phosphorus and nitrogen in algae. This algae can then be directly used as a fertilizer on crops. But then we don’t call it fertilizer anymore, we call it Biofertilizer…