The context is stark. Climate change has disrupted rainfall patterns across India, and the Ministry of Water Resources projects that national water demand will surpass supply by 2050, driven by rising industrial and agricultural needs. In regions such as Palakkad and Coimbatore, the depletion of the Bharathapuzha and Siruvani rivers has already created severe shortages of both drinking and irrigation water. Farmers have been forced to consider brackish groundwater and treated municipal wastewater as alternatives. Against this backdrop, the enormous volumes of effluent generated by breweries, which consume vast quantities of water across malting, mashing, fermentation and clarification, have long looked like a wasted opportunity. Unlike many industrial effluents, brewery wastewater is rich in biodegradable organic compounds such as sugars, starch and ethanol, along with nutrients derived from malt, yeast and processing chemicals.

The research team, led by Senthilraja Kandasamy of Tamil Nadu Agricultural University, began by characterizing the effluent against the irrigation water quality standards of the Food and Agriculture Organization. The picture that emerged was genuinely mixed. On the reassuring side, the wastewater’s pH of 7.85, electrical conductivity of 1.86 decisiemens per meter, suspended solids, calcium, magnesium, sodium and chloride all fell within FAO permissible limits. But several other parameters did not. Total dissolved solids reached 1,320 milligrams per liter, biochemical oxygen demand stood at 22 milligrams per liter, and chemical oxygen demand hit 135 milligrams per liter, more than double the FAO safe limit of 60. Nitrate nitrogen measured 44.5 milligrams per liter, phosphate 6.2, and potassium and bicarbonate also exceeded thresholds. Most concerning for soil structure, the sodium adsorption ratio reached 27.7, well above the value of 18 that signals a sodium hazard, and Kelley’s ratio exceeded 1, indicating water that is formally unsuitable for irrigation without corrective management.

Those caveats matter, but they did not prevent striking results in the greenhouse. The team grew certified maize seedlings in pots filled with garden soil, irrigating them with river water as a control or with brewery wastewater diluted to 25, 50, 75 or 100 percent, in a completely randomized design with five replications. After 45 days, plant height and stem girth showed no statistically significant differences across treatments. But nearly everything else did. Full-strength brewery wastewater significantly increased leaf area, total chlorophyll content, shoot biomass and root biomass compared with river water irrigation. Shoot biomass rose by 12 percent and root biomass by 3 percent under full-strength effluent. Leaf area expanded by roughly 20 percent, and chlorophyll content climbed 16 percent, a change the authors attribute to the wastewater’s abundant magnesium, a central atom in the chlorophyll molecule, and its dual supply of nitrogen as both ammonium and nitrate.

Nutrient uptake told a similar story. Maize leaves under 100 percent brewery wastewater accumulated 28 percent more nitrogen, 15 percent more phosphorus, 19 percent more potassium, 10 percent more calcium, 3 percent more magnesium and 45 percent more sodium than the river-water controls. The researchers note that maize, as a C4 crop with high photosynthetic capacity, is particularly effective at metabolizing nitrogen from wastewater, which may explain why the crop responded so vigorously. One warning sign did emerge: the ratio of sodium to potassium in the seedlings rose steadily as wastewater concentration increased, reaching its highest value under full-strength effluent. Sodium accumulation is a classic precursor of salinity stress, and maize is only moderately tolerant of salty conditions, so this trend will need monitoring in any long-term application.

The soil itself was transformed, in ways that were largely but not entirely positive. After two months of irrigation, soil organic carbon under full-strength effluent reached 0.64 percent, compared with 0.48 percent under river water. Available nitrogen rose by 29 percent on average across wastewater treatments, available phosphorus jumped by nearly 65 percent, and exchangeable calcium, magnesium and sodium all increased significantly. Most strikingly, the soil’s cation exchange capacity, a measure of its ability to hold and exchange nutrients, climbed from 5.27 to 7.94 centimoles of charge per kilogram, an increase of roughly 50 percent. The authors attribute this to the surge in organic matter, whose negatively charged surfaces attract positively charged nutrient ions. Electrical conductivity in the soil also rose sharply, from 0.32 to 1.15 decisiemens per meter, a reminder that dissolved salts accumulate quickly even within a single season.

To make sense of the tangled relationships among 23 soil and plant variables, the team turned to principal component analysis. The first two components captured 75 percent of the variance, and the first alone accounted for nearly 61 percent, loading heavily on organic carbon, available nitrogen, phosphorus and potassium, exchangeable cations and cation exchange capacity. The analysis singled out organic carbon as the property with the most positive influence on both soil quality and plant growth, reinforcing the idea that the effluent’s biodegradable organic load is the engine behind its fertilizing effect. A heatmap of the treatment groups clustered the river-water control apart from the high-concentration wastewater treatments, visually confirming that full and near-full strength effluent produced a distinctly different soil and plant chemistry.

Not everything changed. Microscopic examination of stem and root anatomy revealed that maize plants irrigated with brewery wastewater were structurally indistinguishable from controls. Vascular bundles, sclerenchymatous sheaths, xylem parenchyma, root pith and intercellular spaces all appeared normal, suggesting that at least over a single 45-day growing cycle, the effluent imposed no visible tissue-level stress. That anatomical stability, combined with the biomass and chlorophyll gains, paints a picture of a crop that is not merely tolerating the wastewater but exploiting it, at least in the short term and under controlled conditions.

The authors are careful about what their results do and do not license. This was a pot experiment lasting weeks, not a multi-season field trial, and the wastewater’s elevated chemical oxygen demand, bicarbonate, potassium and sodium adsorption ratio mean that untreated use would carry real risks of soil structural degradation, pore clogging and salinity buildup. They recommend blending brewery effluent with cleaner water, applying calcium-rich amendments such as gypsum or organic manures to displace sodium, monitoring soil salts regularly, and conducting long-term field studies before widespread adoption. They also call for cheaper treatment and filtration technologies tailored to brewery effluent, real-time water quality monitoring, and cost-benefit analyses to make reuse economically viable for farmers. A companion field-level investigation is reportedly underway.

Even with those qualifications, the study fills a genuine gap. Previous work in Ethiopia found brewery effluent to be saline-sodic and harmful to lettuce without gypsum amendments, while earlier research by some of the same Indian authors showed sunflower and sesame thriving on stronger dilutions. The new results extend that evidence to maize, a staple C4 cereal, in one of the world’s most water-stressed agricultural regions. If the sodium hazard can be managed, the arithmetic is compelling: a polluting industrial discharge becomes a nutrient-bearing irrigation source, easing pressure on depleted rivers while cutting the organic load that breweries currently release into waterways. In a state where every bucket of water is rationed and paid for, turning brewery waste into crop water may be one of the more elegant pieces of circular economics to emerge from agricultural science in years, provided the fine print on soil chemistry is respected.

Subject of Research: Use of brewery wastewater as an alternative irrigation source and its effects on soil health and maize nutrient uptake in Tamil Nadu, India

Article Title: Assessment of brewery wastewater as an alternative irrigation source: impacts on soil health and nutrient uptake by maize in Tamil Nadu, India

Article References: Kandasamy, S., Dhandayuthapani, U. N., Subramanian, V., Palanisamy, J., Shanmugam, M. K., Dhakshanamoorthy, D., Subramani, U. K., & Nagappan, S. (2025). Assessment of brewery wastewater as an alternative irrigation source: impacts on soil health and nutrient uptake by maize in Tamil Nadu, India. BMC Agriculture, 1(1), Article 2. https://doi.org/10.1186/s44399-025-00002-0

Image Credits: AI Generated

DOI: 10.1186/s44399-025-00002-0

Keywords: brewery wastewater, irrigation, maize, soil health, nutrient uptake, water scarcity, Tamil Nadu, wastewater reuse, soil fertility, sodium adsorption ratio, organic carbon, sustainable agriculture

The research, conducted by Karuppusamy Priyadharshini and Subramaniapillai Niju of the Department of Biotechnology at PSG College of Technology in Coimbatore, India, addresses a stubborn problem in industrial wastewater management: most biological and electrochemical treatments excel at removing either suspended or dissolved organic matter, but rarely both. Brewery wastewater is particularly difficult because a large share of its chemical oxygen demand, or COD—a core measure of organic pollution—is dissolved rather than particulate. The team’s strategy was to split the workload. Electrocoagulation would strip out suspended solids and nutrients first, and a microbial fuel cell would then consume the remaining soluble organics, generating electricity as a by-product.

Electrocoagulation works by sacrificing an electrode. When a direct current passes through aluminum plates submerged in the wastewater, the anode corrodes electrochemically, releasing aluminum ions into solution. These ions hydrolyze to form aluminum hydroxide species—gelatinous, positively charged flocs known as ‘sweep flocs’—that attract, neutralize, and enmesh negatively charged colloids, suspended particles, and dissolved nutrients. The result is a dense sludge that settles readily, carrying phosphates, nitrates, and particulate organic matter out of the water. Compared with conventional chemical coagulation, the process adds no sulfate or chloride salts, produces less sludge, and requires only simple equipment.

Like any electrochemical process, however, electrocoagulation lives or dies by its operating conditions. Apply too little current and floc formation is sluggish; apply too much and energy costs spiral while the electrodes passivate. The initial pH governs the speciation of aluminum hydroxide and thus coagulation efficiency, while electrolysis time determines how much contaminant is captured. Rather than testing conditions one variable at a time, the researchers employed the Central Composite Design (CCD) of Response Surface Methodology (RSM), a statistical framework that models the interaction between variables and locates the optimum with far fewer experiments. Their twin objectives were ambitious but practical: maximize COD removal while minimizing energy consumption per cubic meter of wastewater treated.

The optimization paid off. At a pH of 6.6, a current density of 13.2 milliamperes per square centimeter, and an electrolysis time of just 39.3 minutes, the process achieved a mean COD removal of 44.2 percent at an energy consumption of 11.14 kilowatt-hours per cubic meter. That COD figure may look modest, but the composition of the remaining pollution tells a more encouraging story. Under the same optimized conditions, the electrocoagulation stage removed 88 percent of total suspended solids, 71.6 percent of nitrate, and a striking 93.17 percent of phosphate. Soluble COD, by contrast, fell only 11.5 percent—confirming the team’s hypothesis that the bulk of brewery COD is dissolved and therefore largely invisible to coagulation chemistry. The electrochemical step was, in effect, expertly doing the wrong half of the job if deployed alone.

That is where the microbes come in. The researchers diluted the electrocoagulation-treated effluent to one-third strength and fed it into a dual-chambered microbial fuel cell fitted with an abiotic cathode. In a microbial fuel cell, electroactive bacteria colonize the anode and, in metabolizing organic matter, transfer electrons to the electrode instead of to oxygen or other dissolved acceptors. The electrons flow through an external circuit to the cathode, producing usable current, while protons migrate across the membrane to complete the reaction. Because soluble organics are precisely what these exoelectrogenic bacteria eat, the MFC is the ideal complement to the coagulation stage.

The results validated the pairing decisively. The microbial fuel cell removed 91.9 percent of the COD remaining after electrocoagulation and delivered a peak power density of 11.81 milliwatts per square meter. The final effluent met discharge standards, meaning the two-stage system accomplished what neither stage could alone: electrocoagulation efficiently removed the suspended organic fraction and nutrients, while the bioelectrochemical stage polished off the soluble fraction and harvested a modest electrical dividend from the electrons liberated during microbial metabolism. The authors emphasize that the two processes are fundamentally complementary—each targeting the pollutant fraction the other misses.

The study also claims a methodological first. According to the authors, this is the first investigation to statistically optimize the electrocoagulation pre-treatment of brewery wastewater using CCD-RSM within a sequential electrocoagulation–microbial fuel cell configuration. That matters because electrocoagulation is energy-intensive, and its economics hinge on running it at the sweet spot where contaminant removal per kilowatt-hour is highest. By formally treating energy consumption as an optimization objective alongside COD removal, the study provides a template that other industries—dairies, distilleries, paper mills—could adapt for their own high-strength effluents. The funding came from India’s Department of Science and Technology under the KIRAN division’s Women Scientist Scheme A, reflecting a deliberate national investment in women-led applied research.

The broader significance extends beyond the laboratory numbers. Water scarcity and stringent discharge regulations are squeezing breweries worldwide, and conventional aerobic treatment of such strong effluent is expensive, energy-hungry, and generates substantial sludge. Hybrid electrochemical-bioelectrochemical trains invert that logic: the electrical step does the heavy lifting on solids and nutrients in under forty minutes, the biological step converts residual organics into electricity rather than requiring external aeration energy, and the optimized design keeps the power bill bounded. Power densities from microbial fuel cells remain modest compared with grid electricity, and scaling from bench-top dual-chamber reactors to full-scale basins is a formidable engineering challenge—electrode materials, membrane fouling, and microbial community stability all demand attention.

Still, the study offers something the field has often lacked: a statistically defensible, energy-aware integration of two complementary technologies, tuned on real brewery effluent and benchmarked against discharge standards. If subsequent pilot-scale work can preserve these efficiencies at volume, the humble brewery could evolve from an environmental liability into a demonstration site for wastewater treatment that cleans water, recovers nutrients, and squeezes a little electricity out of every drop of waste.

Subject of Research: Sequential electrocoagulation and microbial fuel cell treatment of brewery wastewater

Article Title: Optimization of electrocoagulation and integration of microbial fuel cells for brewery wastewater treatment

Article References: Priyadharshini, K., & Niju, S. (2026). Optimization of electrocoagulation and integration of microbial fuel cells for brewery wastewater treatment. Clean Technologies and Environmental Policy, 28(10), Article 252. https://doi.org/10.1007/s10098-026-03607-4

Image Credits: AI Generated

DOI: 10.1007/s10098-026-03607-4

Keywords: brewery wastewater, electrocoagulation, microbial fuel cells, COD removal, response surface methodology, central composite design, water treatment, bioelectricity, aluminum electrodes, phosphate removal, total suspended solids, wastewater optimization