Using Algae-Based Water Treatment to Clean Field Runoff

Healthy agriculture depends on healthy water. Rainfall moving across cultivated land can carry soil particles, nutrients and organic matter into drains, creeks and wetlands. Treating that runoff before it reaches surrounding waterways can help protect biodiversity, preserve water quality and support resilient food production.

Algae-based water treatment offers one promising approach. In carefully managed systems, selected algae absorb nutrients such as nitrogen and phosphorus while sunlight, settling and biological activity help improve the quality of captured water. The resulting biomass may also provide useful information about nutrient flows across a farm.

For Fresh Del Monte Produce, this technology fits within a broader sustainability strategy covering responsible agriculture, environmental protection and community wellbeing. Any application must be designed for local conditions, regulated appropriately and evaluated alongside established measures such as vegetated buffers, erosion control and efficient fertiliser use.

The Australian context makes practical water stewardship especially important. Farms near Cairns, Darwin, Perth and regional river systems experience very different rainfall patterns, while growers supplying supermarkets in Sydney, Melbourne and Brisbane face strong expectations around food safety, traceability and responsible production.

How Algae Improve Runoff Quality

Algae are microscopic aquatic organisms that use light, carbon dioxide and nutrients to grow. In a treatment pond or covered raceway, they can take up dissolved nitrogen and phosphorus that would otherwise move downstream. As algae grow, some nutrients become part of the biomass and can later be removed through harvesting or controlled settling.

The treatment process is most effective when it is part of a sequence. A sediment basin can first slow water and capture soil, followed by an algae pond that targets dissolved nutrients. Further filtration, polishing wetlands or managed discharge points may then improve clarity and reduce the risk of suspended material leaving the site.

Performance depends on sunlight, water temperature, retention time, pH, nutrient concentration and hydraulic design. Australian farms may require different systems for intense wet-season flows in Far North Queensland than for winter rainfall around Perth or irrigated production near the Murray–Darling Basin. A design that works in a tropical climate cannot simply be transferred without local testing.

Connecting Treatment With Farm Management

Runoff treatment should complement prevention. Soil cover, contour planting, precise irrigation, controlled traffic and well-timed fertiliser applications can reduce the amount of sediment and nutrients entering drains in the first place. Maintaining groundcover is especially valuable where intense storms can expose soil between crop cycles.

Monitoring can reveal whether a treatment system is addressing the actual source of pollution. Sensors and sampling can track flow volume, turbidity, electrical conductivity, dissolved oxygen, nitrogen, phosphorus and algal density. Specialist water monitoring equipment can support consistent measurements, helping farm teams compare results before and after rainfall events.

Field records also matter. Linking runoff results with fertiliser applications, irrigation schedules, soil type and weather data can show which practices deliver the greatest improvement. This creates a more complete environmental management system rather than treating a pond as an isolated piece of infrastructure.

Designing For Australian Conditions

Australia’s climate creates both opportunities and constraints for algae-based water treatment. Strong sunlight can support algal growth, yet extreme heat may lower oxygen levels or encourage unwanted organisms. Heavy storms can overwhelm ponds, while long dry periods can concentrate salts and nutrients in limited water volumes.

Farm operators must also consider biosecurity. Algal cultures need to remain contained, and systems should prevent escape into natural waterways. Designs require reliable overflow controls, safe harvesting procedures and contingency plans for equipment failure. Local approvals may apply under state environmental and water legislation, particularly where treated water is discharged or reused.

Regional context should guide site selection. A banana-growing operation near Cairns may need stormwater capacity for intense rainfall, whereas a farm outside Adelaide may focus on evaporation, salinity and limited freshwater availability. Near Perth, sandy soils and groundwater sensitivity can influence drainage design, while operations closer to Brisbane may need to account for floodplain conditions.

Recovering Value From Algal Biomass

Harvested algae contain nutrients that originated in the farm’s runoff. If the biomass is tested and managed correctly, it may be suitable for controlled composting or another approved beneficial use. Returning nutrients to soil can support circular resource management, although safety, contaminant levels and regulatory requirements must be assessed before any reuse.

Biomass should never be applied automatically. Treatment ponds can collect trace contaminants, pathogens or excessive salts, depending on the catchment and farm inputs. A responsible programme would include laboratory testing, documented handling and clear criteria for disposal or reuse.

The broader value may be informational as well as material. Changes in algal growth can indicate shifts in nutrient loading, water residence time or seasonal conditions. Combined with work on soil carbon mapping, this data can help build a fuller picture of how agricultural soils, water and climate practices interact.

Protecting Biodiversity And Communities

Improved runoff quality benefits wetlands, streams and coastal ecosystems. Lower nutrient loads can reduce the risk of excessive plant growth and oxygen depletion downstream. This matters in regions connected to sensitive catchments, including waterways that eventually flow toward the Great Barrier Reef or urban estuaries around Sydney and Melbourne.

Well-designed treatment areas can also provide habitat for insects, birds and other species, provided they do not become sources of invasive organisms or uncontrolled algal blooms. Native plantings around ponds can stabilise banks, provide shade and create a buffer between production areas and water infrastructure.

Community confidence depends on transparency. Farmers, workers, Traditional Owners, local authorities and nearby residents should be able to understand what the system is designed to do, how it is monitored and what happens during unusual weather. Clear signage, accessible reporting and local engagement can make environmental infrastructure part of community stewardship rather than an unseen operational feature.

Measuring Outcomes Responsibly

A credible programme needs a baseline. Before installation, teams should measure runoff quality at representative points and record rainfall, flow, crop activity and fertiliser use. After commissioning, the same indicators should be monitored across dry periods, ordinary rainfall and major storm events.

Useful measures include kilograms of nitrogen and phosphorus removed, sediment captured, volume of water treated, energy used and the proportion of biomass safely managed. Biodiversity observations, maintenance records and incident reports can add context to laboratory results. Reporting both successes and limitations supports responsible decision-making.

Data quality is essential. Sampling methods should be consistent, equipment should be calibrated and results should be reviewed by appropriately qualified specialists. Where possible, treatment performance should be compared with control areas or historical data, allowing the business to distinguish genuine improvement from seasonal variation.

Moving From Pilot To Practice

A staged pilot can test whether algae-based treatment is suitable for a particular agricultural site without committing immediately to a large installation. The first stage may map drainage pathways and identify the highest-priority runoff points. The next can evaluate a small treatment cell through contrasting weather conditions, followed by a review of nutrient removal, operating costs and maintenance demands.

This approach supports collaboration across agronomy, engineering, environmental science and farm operations. It also creates opportunities to share practical learning with Australian growers, research institutions and regional catchment groups. Lessons from tropical, temperate and semi-arid sites can inform better designs across the company’s global agricultural operations.

The objective is clean water supported by sound land management, not technology for its own sake. The immediate next step is to select one representative drainage catchment, establish a pre-treatment water-quality baseline and run a monitored algae-based pilot through a complete wet-season cycle.