Onondaga Lake is located in Central New York, northwest of Syracuse New York. Onondaga Lake is known as one of the most polluted lakes located in the United States. Due to the lack of regulations in the past, there were major problems with both sewage and chemical pollution into the lake. For a while, Syracuse dumped human waste into the lake with little to no treatment. This had caused major problems with algal blooms and Eutrophication. Factories that were located along the shoreline of the lake were also dumping toxic chemicals into the lake such as Mercury. These chemicals are still found within the sediment at the bottom of the lake.
In 1955, the Syracuse Sewage Treatment Plant was transferred to Onondaga County. This treatment plant was upgraded in 1959-1960 and was renamed the Metropolitan Syracuse Wastewater Treatment Plant (Metro). The wastewater that is currently being treated here is being discharged into Onondaga Lake. Metro treats around 80 million gallons of wastewater daily which is produced by the 270,000 residents of Onondaga County and many industrial commercial customers in the city of Syracuse. Metro is a conventional wastewater treatment system meaning that the process used to treat the wastewater requires energy, outside chemicals and machines. There are three main stages that are used to clean the water which are primary, secondary and tertiary treatment.
In Primary treatment, solid materials are separated from the wastewater, through a screening process, a sand/gravel settlement process, and a final low energy settlement (primary clarifier) process. At this final stage, oil and grease is also skimmed from the surface of the wastewater. In Secondary treatment, aeration tanks are used where aerobic bacteria are provided oxygen and consume the dissolved organic waste. Upon leaving the aeration tanks, the bacteria and associated materials are allowed to settle out in secondary clarifiers. At this point greater than 98% of the waste has been removed from the wastewater.
In Tertiary treatment, wastewater is pumped to the new tertiary treatment facility at Metro. This new facility is a new state-of-the-art process for year-round removal of ammonia and phosphorus. The facility utilizes a biological aerated filter to remove ammonia through the growth of oxidizing nitrogen bacteria on polystyrene beads. The wastewater is then sent on to a high rate flocculate settling system (HRFS) to remove phosphorus, by adding an iron oxide compound and other flocculating compounds to the waste water. Fine sand is then added to the water and the phosphorus floc is settled out with the sand. Upon leaving the HRFS the wastewater is then disinfected utilizing ultraviolet radiation during warm weather months. UV radiation is utilized as an alternative to chlorination of the water, as chlorination residue in the water discharged to Onondaga Lake is harmful to the lake's ecology. UV radiation sterilizes the bacteria and does not produce a harmful residue.
Are there other ways that this wastewater can be treated? The answer is yes. The alternative to conventional wastewater treatment systems are natural systems. Natural wastewater treatment systems don’t require the desired inputs that conventional systems do. Conventional wastewater treatment systems are more capital and energy intensive as compared to natural treatment. A prime example of a natural wastewater treatment system which was invented by John Todd is the Living Machine. The purpose of the Living Machine was to use a series of plant ecosystems that work together in order to clean water. This approach offers a natural and eco-friendly alternative to expensive conventional water treatment plants. The most basic design requires a minimum of three different ecological systems that process the water in different ways. Each ecological system is isolated from the others in order to allow each individual system to treat the water in its own unique way. Each of these ecosystems don’t only persist of plants, many other forms of life are involved such as bacteria, fungi, snails, clams and fish which all thrive in breaking down these pollutants.
Another example of a natural wastewater treatment system is a constructed wetland. Constructed or even natural wetlands are well known to improve the quality of water. Wetlands have a high species richness meaning that many forms of life have the ability to live together in these ecosystems. Looking at the holistic view of the ecosystem instead of each individual part, ecological engineers are able to design wetlands that have the ability to treat water using select species that work together. Would it have been logical to have used these natural systems to treat the water flowing into Onondaga Lake instead of the conventional water treatment plant used now? What if we replaced the Metro plant with a bunch of natural systems? How would you like your water to be treated? What are your thoughts and comments about this topic?
Also if you took the quiz from last weeks element and are curious about the answers read up on them here.