How Phytoplankton Can Transform City and County Lakes Fed by Treated Wastewater
- Dr. Algae
- Jun 26
- 7 min read
Wastewater treatment facilities across the United States process 34 billion gallons daily while discharging significant nitrogen and phosphorus levels into lakes and waterways.
EPA data shows 58% of river and stream miles and 40% of lake acres contain excess nutrients that trigger harmful algal blooms and serious water quality problems. Municipal treatment systems remove many contaminants but consistently fail to eliminate these nutrients completely.
Phytoplankton offers a natural solution to nutrient-polluted water bodies fed by treated wastewater. These microscopic organisms absorb excess ammonia, nitrite, nitrate, and phosphate that conventional treatment methods leave behind. Phytoplankton work within existing ecological processes to restore water balance while avoiding the harmful effects of chemical treatments like copper sulfate that damage beneficial organisms such as zooplankton, which are essential to fish fry and other organisms.
Cities and counties face mounting economic pressure from water management costs. American households spend approximately $500 annually on wastewater collection and treatment, while facilities generate 13.8 million tons of biosolids yearly.
Phytoplankton offers municipalities a cost-effective approach that addresses nutrient pollution while supporting both recreational water use and agricultural irrigation needs. This biological method creates sustainable solutions for communities dealing with wastewater discharge impacts on their water resources.
The problem with nutrient pollution in treated wastewater
Nutrient pollution creates serious ecological problems in freshwater systems despite advances in wastewater treatment technology. Treatment facilities discharge excess nitrogen and phosphorus that fuel cascading environmental damage across water bodies.
How ammonia and phosphate affect freshwater lakes
Ammonia and phosphate function as fertilizers in water bodies, driving excessive algae growth with the potential to eventually lead to eutrophication. Ammonia shifts from its relatively harmless ammonium (NH4+) form to toxic ammonia (NH3) as lake conditions change, killing fish at concentrations as low as 0.016 mg/L [11]. This toxicity increases dramatically with higher pH and temperature [11].
Fish exposed to ammonia suffer physical damage to their gills, liver, kidneys, and other organs [15]. Sublethal ammonia levels reduce swimming activity, disrupt feeding behavior, and impair fishes' ability to escape predators [15].
Phosphates drive algal blooms through bacteria consumption of dissolved oxygen when massive algae populations die and decompose. This process creates dead zones where aquatic life cannot survive [2]. Certain algae species produce toxins harmful to wildlife and humans who contact affected water [3].
Sources of nutrient pollution in city and county water bodies
Municipal wastewater treatment facilities release nitrogen and phosphorus from human waste, food residues, and cleaning products [4]. Stormwater runoff carries nutrients from fertilized lawns, pet waste, and urban surfaces directly into water bodies without filtration [15]. Combined sewer overflows discharge untreated sewage during heavy rainfall events [15]. Septic systems contribute significantly when improperly maintained, with 10-20% failing during their operational lifetime [4].
These sources collectively create the nutrient overload affecting 40% of rivers, streams, and lakes nationwide [6].
Why traditional wastewater treatment isn't enough
Conventional wastewater treatment plants lack the advanced tertiary treatment systems needed to eliminate contaminants of emerging concern, heavy metals, and harmful bacteria [7]. Most facilities cannot completely remove nutrients for this reason.
Treated wastewater releases significant nitrogen and phosphorus into receiving water bodies as a result. Standard treatment methods become especially problematic during population growth, when facilities face increased volumes without corresponding technological upgrades.
Standard treatments fail to address complex interactions between different pollutants and cannot adapt to seasonal variations in wastewater composition. Communities and agricultural operations dependent on these water sources face serious economic and environmental challenges from this degradation.
Phytoplankton as a Natural Solution for Lake Restoration
Phytoplankton provides a biological approach to restoring lakes affected by nutrient-rich wastewater discharge. These microscopic organisms work within natural ecological cycles to restore water balance rather than simply removing contaminants through chemical intervention.
What is phytoplankton and how does it work?
Phytoplankton are single-celled algae that form the foundation of aquatic food webs. These primary producers absorb nutrients, convert carbon dioxide to oxygen through photosynthesis, and provide food for zooplankton. Phytoplankton respond naturally to environmental changes, making them effective indicators of water health [8].
Phytoplankton produce oxygen through photosynthesis which enhances aerobic degradation of pollutants by beneficial bacteria [9]. Their rapid reproduction cycle allows them to quickly absorb excess nutrients that would otherwise fuel harmful algal blooms. Phytoplankton support biodiversity by providing essential food for zooplankton, which then feed fish and other aquatic organisms.
NATURAL METHOD TO OUTCOMPETE HARMFUL ALGAE:
Traditional copper treatments cause immediate 83% declines in algal populations but trigger massive 2,617% increases within five days [10]. Copper-based treatments reduce beneficial zooplankton by 43%, eliminating natural algae controllers [10].
Phytoplankton strains like Chlorella vulgaris reduce cyanobacteria dominance by 87% in nutrient-rich waters without harming beneficial organisms [11]. Concentrated phytoplankton from Hydralife Solutions competes with bad algae and reproduces as they absorb excess nutrients, providing a sustainable solution to problematic algae. Phytoplankton stabilize oxygen levels through continuous photosynthesis rather than causing harmful die-offs that deplete oxygen [11].
Role in ammonia removal and phosphate reduction
Phytoplankton effectively absorb nitrogen and phosphorus from wastewater as they grow [12]. They convert toxic ammonia nitrogen into organic matter, simultaneously removing this harmful compound and producing nutritious food for zooplankton [11].
Phytoplankton functional groups adapt to different nutrient conditions, with specific groups thriving in varying nitrogen and phosphorus concentrations [8].
Phytoplankton access both inorganic and organic nutrient pools through direct uptake, enzymatic hydrolysis, and symbiotic relationships with microbial communities [13].
Impact on harmful algal blooms and water clarity
Harmful algal blooms occur when nutrient imbalances favor toxic species like Anabaena, Oscillatoria, and Microcystis [12]. Phytoplankton communities compete directly with these harmful species for nutrients, effectively starving them [11].
Research shows that land-water transition areas improve phytoplankton quantity and quality, subsequently increasing zooplankton biomass and trophic transfer efficiency [14]. Dense phytoplankton communities limit light penetration to submerged weeds, naturally controlling macrophyte growth without chemicals [11].
A 2021 study of irrigation ponds found that managed phytoplankton communities reduced cyanobacteria by 50% within six months while decreasing sediment copper levels by 30% [11]. This demonstrates phytoplankton's potential for sustainable lake restoration without chemical intervention.
How phytoplankton transforms treated greywater and blackwater lakes
Municipal water bodies contaminated by wastewater discharge present complex challenges that phytoplankton addresses through natural biological processes. These microscopic organisms actively compete with harmful algae while establishing balanced aquatic ecosystems.
Case studies of phytoplankton in municipal lake systems
Lake Jeziorak Mały demonstrates phytoplankton's effectiveness in urban water restoration. Researchers implemented storm water pretreatment separators and fountain-based aeration systems that produced substantial decreases in harmful cyanobacteria proportions alongside increased diversity of beneficial phytoplankton groups [15]. This shift created greater water visibility, improved oxygenation, and reduced orthophosphates, transforming the lake from polytrophic to a more balanced eutrophic state [15].
BIOLOGICAL WATER TREATMENT RESULTS:
High-Rate Algal Pond technology demonstrates impressive nutrient removal capabilities. Phytoplankton-based systems remove 26.6-75.7% of nitrogen with a 61.23% median and 21.89-94% of ammonia with a 77% median from wastewater [1]. Phosphorus removal ranges from 10.48-97.2% with a 42.73% median, directly addressing the primary driver of harmful algal blooms [1].
Phytoplankton simultaneously purify water through direct contaminant uptake and facilitate bacterial degradation of organics by generating oxygen through photosynthesis [1]. The resulting biomass can be harvested for biofuel production, creating circular economy benefits [1].
Improving biodiversity and supporting zooplankton
Phytoplankton communities create cascading positive effects throughout aquatic ecosystems. Phytoplankton diversity directly influences zooplankton communities, which serve as the crucial intermediary between algae and fish populations [17].
Diatoms support rotifer development while green algae and certain cyanobacteria foster microcrustacean populations like Copepoda and Cladocera [17]. This relationship maintains efficient energy transfer from phytoplankton to zooplankton, supporting productivity at higher trophic levels [18] and ultimately sustaining recreational fishing opportunities and overall ecosystem health.
Community and Agricultural Benefits of Phytoplankton-Based Lake Management
Phytoplankton-based lake management delivers practical benefits that extend far beyond water quality improvements. Communities gain access to cleaner recreational waters while farmers receive improved irrigation sources that support crop production since phytoplankton is a biostimulant to soils.
Water Quality Restoration for Recreational and Irrigation Use
Phytoplankton systems eliminate the risk of harmful cyanobacteria blooms that produce dangerous toxins affecting humans and animals [12]. Lakes managed with phytoplankton show dramatic improvements in water clarity, creating safe conditions for swimming, fishing, and boating activities that generate permit and user fee revenue [19]. Property values increase around well-maintained water bodies as they become sources of civic pride and enhanced quality of life for residents [5].
Municipal Cost Savings and Sustainable Operations
Cities and counties benefit from phytoplankton's preventative approach to lake management. Traditional reactive treatments require costly emergency interventions when algae problems become severe, while phytoplankton provides consistent, predictable maintenance costs [19]. This proactive biological method addresses problems before they become expensive to manage [20]. Municipalities reduce their reliance on chemical treatments and energy-intensive processes, resulting in more sustainable operations than conventional methods [9].
Cleaner Water Sources for Local Farming Operations
Agricultural areas surrounding phytoplankton-managed lakes experience significantly fewer toxic algae contamination issues [21]. Farmers receive irrigation water that reduces crop contamination risks and associated testing expenses. Water from phytoplankton-balanced systems contains beneficial nutrients in stable forms that support plant growth without the problematic effects of untreated wastewater discharge.
Nutrient Recovery Through Struvite Formation
Struvite (MgNH4PO4) recovery from wastewater streams offers farmers an alternative to conventional phosphorus fertilizers [22]. This crystalline mineral functions as a slow-release fertilizer containing 5.7% nitrogen and 12.6% phosphorus by weight [23]. Field applications demonstrate that struvite-based fertilizers perform comparably to synthetic products while reducing runoff concerns due to lower water solubility [22]. This nutrient recovery approach prevents pollution while providing agricultural communities with sustainable fertilizer sources [24].
Conclusion
Phytoplankton provides municipalities with a natural method to address wastewater nutrient pollution in lakes and waterways. These microscopic organisms absorb excess ammonia, nitrate, and phosphate while supporting aquatic ecosystems through continuous oxygen production and food web enhancement.
Cities and counties benefit from reduced water management costs compared to reactive chemical treatments. Phytoplankton-based systems require less intervention once established, providing predictable budgeting for water resource management. Municipal lakes become community assets that generate revenue through recreational use while supporting agricultural irrigation needs.
Farmers gain access to cleaner irrigation water that reduces crop contamination risks. The potential for nutrient recovery through struvite formation creates sustainable fertilizer alternatives, supporting circular economy practices that benefit agricultural productivity.
Copper sulfate and similar chemicals create harmful boom-and-bust cycles that damage beneficial organisms. Phytoplankton communities work continuously to prevent harmful algal blooms while maintaining water quality through natural ecological processes.
This biological approach addresses the root cause of nutrient pollution rather than treating symptoms after problems develop. Communities seeking cost-effective solutions for wastewater-fed lakes should consider phytoplankton as their primary management strategy for sustainable water quality improvement.
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