A wastewater treatment system might be made up of the technologies necessary to remove any number of the following:
Biochemical oxygen demand, or BOD, refers to the amount of dissolved oxygen needed by aerobic biological organisms to break down organic matter into smaller molecules. High levels of BOD indicate an elevated concentration of biodegradable material present in the wastewater and can be caused by the introduction of pollutants such as fecal waste, cleaning, and wash-down from food processing or fertilizer runoff.
If large amounts of nitrates and/or phosphates are not removed from wastewater and these nutrients are discharged into local environments, they can lead to an increase BOD and extensive weed growth, algae, and phytoplankton. This can further lead to eutrophication, or the deoxygenation in a body of water, killing the organisms and potentially leading to hypoxia or environmental dead zones.
Pathogens are bacteria, viruses, fungi, or any other microorganisms that can be present in wastewater that can lead to all kinds of health issues, including acute sickness, severe digestive problems, or death. When domestic or industrial wastewater contains these harmful pathogens and is not treated, it can spread illnesses and diseases such as cholera, dysentery, salmonellosis, hepatitis A, botulism, and giardiasis, to name a few.
Mostly found in wastewater as a result of various industries, manufacturing processes, when left in wastewater in high concentrations, metals can cause extensive damage to the environment and human health. They are particularly damaging because they don’t break down and tend to accumulate, causing toxic environs.
Total suspended solids (TSS) in wastewater, the organic and inorganic solid material suspended in the water, can, like many of the other contaminants listed, harm aquatic life. They can also be problematic if the wastewater is being reused for a process, so depending on whether or not you need to discharge your wastewater in a publicly owned treatment works (POTW) or environment, or reuse the wastewater for process, will determine how harmful the TSS will be. TSS can decrease levels of oxygen in aquatic environments and kill of insects. They can also scale and foul piping and machinery.
Total dissolved solids (TDS) are any anions, cations, metals, minerals, or salts found in wastewater. They can cause issues with aquatic life, irrigation and crops, and they can also seep into groundwater. TDS can be generated in wastewater from just about any industry.
When pesticides and other chemicals are used / made in the manufacturing process, they can be transmitted to humans and the environment through wastewater, causing damage to the environment and human health. Some common chemicals found in wastewater include diethylstilbestrol, dioxin, PCBs, DDT, and other pesticides. These “endocrine disruptors” can block hormones in the body and affect the functions these hormones control.