What Is In Our Wastewater?

In 2015, the United Nations adopted 17 Sustainable Development Goals. One of these goals in particular is to ensure availability and sustainable management of water and sanitation for all. But before we try and do something about this, we need to understand one particular aspect of what gives rise to the lack of sanitized water for many countries in the first place, which is the composition of our wastewater that we release into the environment.

Being the most important resource for a functioning civilization, it is vital that we understand the nature and characteristics of wastewater for its effective treatment and management.

Let’s begin this discussion by pointing out that all of us play a role in the constituents of wastewater because all of us use water constantly, cooking, cleaning, personal hygiene, we couldn’t live without it.

Human waste such as urine and excretion are the biggest contributors to the constituents of wastewater as far as “natural waste” is concerned.

Commercial and pharmaceutical consumptions are also a major factor in the issue of wastewater. Toothpaste, shampoo, conditioners, dish soap, medicines, vitamins and the list goes on. These constituents from your household are transported to the main council plumbing to the wastewater treatment plant.

Some of the major types of constituents that occur in wastewater are as follows:

• Suspended solids: these are small particles which remain in suspension in water as their name suggests. These are an important indicator of water quality, the more suspended solids present, the more cloudy the water.

• Biodegradable organics: these are substances that are food for naturally occurring micro organisms. In their dissolved form in wastewater, these normally comprise of fats, proteins, starches, acids, alcohols, esters and aldehydes. These can be a result of various sources such as domestic or industrial wastewater discharge. They could also be an end-product of plant or animal tissue.

• Pathogens: these are organisms that cause diseases, the most common forms being viruses, bacteria, fungi and parasites.

However, in this blog I am going to focus on the issue of heavy metals being discharged into our wastewater. In order for society to become more mindful about what goes into our wastewater, it is crucial that we understand how pollution in the wastewater affects our health and lifestyle.

Let’s face it, what will be the bigger incentive for us to actually do something about our wastewater, it’s impact on our environment or our health?

With the number of developed nations increasing, heavy commercial and industrial activities have been a contributing factor to the presence of heavy metals in wastewater. In large quantities, metals such as lead, mercury, arsenic and cadmium are the most toxic heavy metals and when present in wastewater, they present a large risk to the environment, animals and humans. These heavy metals can also contaminate drinking and land irrigation water.

As far as the impact of heavy metals in wastewater is concerned, there is extensive evidence which shows that species of fish such as tuna and swordfish contain the highest levels of mercury. These levels can prove fatal to the human immune system in the long term if consumption of these species is not done in moderation.

Source: https://globalseafoods.com/blogs/news/low-mercury-seafood

So how do mercury and other heavy metals end up in our marine ecosystems in the first place?

Ok, I’ll admit that we are not the only reason for heavy metals ending up in our marine ecosystems. Heavy metals are also introduced into water through weathering and erosion of soils and rocks as well as from volcanic eruptions.

However, the most common heavy metal pollution in freshwater comes from industrial and mining operations, giving rise to toxic conditions for marine organisms in their natural environment. More information on this link below.

https://www.lenntech.com/aquatic/metals.htm

But when dealing with the issue of wastewater treatment, we also have to approach it from a perspective of population growth into the future. As populations in cities increases, the level of industrial activity increases proportionally to meet our demands and services. Hence, the concentrations of heavy metals in water will also increase in addition to the amount of pollutants and harmful substances present in the water.

Heavy metals in our wastewater is bad for the environment AND for us. What can we do about it?

One of the most effective ways of removing heavy metals from wastewater is through a process known as Ion Exchange. From basic high school chemistry, we know that there are two types of ions, cations (positively charged) and anions (negatively charged).

This process occurs between a substance known as a resin (in solid form) and a liquid such as wastewater. Essentially, positively charged cations are exchanged with the resin’s cations on the surface., vice versa for the anions. In most ion exchange processes, sodium is used for the cations on the resin’s surface while chloride takes the place of anions. Further information is available from this link below:

https://pdfs.semanticscholar.org/428f/d34c37f3b95900d80119e5726d3e17a73ace.pdf

We can see that what goes into our wastewater has a huge impact on the quality of water in our marine ecosystems and urban water bodies. When looking at the bigger picture of wastewater, heavy metals are only part of the problem and ion exchange is only part of the solution. Many developing nations do not have the sufficient infrastructure and facilities to undertake wastewater treatment processes such as Ion Exchange. Investigation of new and innovative methods must be encouraged and pushed for by public and private sectors around the world for us to achieve our sustainable development goal of clean water and sanitization for all.