Articles 27 Mar, 2017

Improve water quality in waste stabilization ponds

In short

  • Due to population growth, accelerated urbanization, and economic development, the quantity of wastewater is increasing globally;
  • Although there are several methods to treat wastewater, this article focuses on stabilization ponds (aka lagoons, or waste stabilization ponds);
  • MPC-Buoy controls and monitors algae for higher water quality that’s safe for the environment.

Mainly in low-income areas, a large proportion of wastewater is discharged directly into the environment. Unfortunately, not all treatment plants have the capacity to remove pollutants that damage the ecosystem and harm people. Treated wastewater usually contains high nutrient levels, fueling algae blooms in storage ponds. It’s important to treating algae in wastewater lagoons to improve the overall water quality before discharge.

Algae growth in stabilization ponds

An important factor to consider in wastewater reuse and treatment is algae growth, which is relatively common in warm and nutrient-rich waters. Treated wastewater contains high nutrient concentrations which cause blooms on the surface of storage ponds and clog irrigation systems (filters, emitters, distribution pipes). Some freshwater algae species form Harmful Algal Blooms (HABs), posing a threat to the environment, people, plants, and fish.

There are several methods to treat wastewater; yet, in this article we’ll focus on stabilization ponds (also called lagoons or waste stabilization ponds). These kinds of water bodies consist of in-ground earthen basins, in which waste is detained for a specified time (retention time) before discharge. The size and depths can vary, as well as the degree of treatment. Lagoons are typically classified by their degree of mixing and the amount of dissolved oxygen.

Examples of lagoons are: anaerobic-, facultative-, aerobic-, partial-mix aerated-, and completely mixed- aerated lagoons.

Controlling algae before discharge

1. Compliance with wastewater quality standards

One of the Sustainable Development Goals (SGDs) is improving water quality by halving the proportion of untreated wastewater. Globally, over 80% of the wastewater generated by society flows back into the ecosystem without being treated or reused (Sato et. al, 2013).

The Clean Water Act of 1970 and the Federal Water Pollution Control Act Amendments of 1972, established the National Pollutant Discharge Elimination System, or NPDES—an effort to assure that wastewater discharge won’t harm aquatic recreation or wildlife.

The NPDES permit identifies monthly averages and maximum levels of BOD, TSS, and Fecal Coliform allowed in the treatment plant effluent. In larger systems, as well as systems that discharge into sensitive surface waters or groundwater supplies, NPDES permits may also require nitrogen and phosphorous removal.

2. Lower biochemical oxygen demand levels

Biochemical Oxygen Demand (BOD) is an indicator of biological pollution in water. Industrial wastewater is characterized by high BOD levels. Increasing water supply and disposal prices, together with increased environmental regulations, require wastewater to be treated in a eco-friendly and cost-effective manner before discharge.

If these organics aren’t stabilized during the treatment process, dissolved oxygen (DO) will deplete from the receiving water. This oxygen depletion often results in fish kills and damage of the aquatic ecosystem.

3. Lowering total suspended solids

Total Suspended Solids (TSS) include all particles suspended in water which can’t pass through a filter. In terms of water quality, high levels of TSS increase turbidity and decrease DO levels. This can affect the operation process.

Our MPC-Grid technology was developed to increase treated wastewater quality in stabilization ponds and facultative lagoons. Algae can grow in wastewater while being treated. In doing so, they decrease the treated water quality. This means, treated wastewater won’t comply with government regulations.

MPC-Grid controls and monitors the algae for higher quality water that’s safe to release back into the environment. Besides controlling algae growth, the system reduces BOD, TSS, and pH levels. The MPC-Grid has a monitoring system, providing real-time water quality data.