Bugs need feeding. Many industrial effluents — brewery, dairy, sugar, distillery, refinery — are rich in carbon but starved of nitrogen and phosphorus, so the biomass that should treat them simply can't grow. Controlled nutrient dosing restores the BOD : N : P balance, prevents filamentous bulking, and keeps a biological plant stable and compliant.
A healthy aerobic biomass needs carbon, nitrogen and phosphorus in roughly BOD : N : P = 100 : 5 : 1 (anaerobic systems need far less). High-carbon industrial effluents routinely fall short, and the symptoms are unmistakable: poor COD removal, dispersed or filamentous sludge that won't settle, low MLSS and a plant that never quite hits consent. Dosing a nitrogen source (urea, ammonia or DAP) and a phosphorus source (phosphoric acid or DAP) in proportion to the carbon load restores the ratio and the biology recovers. The dose is set from the influent BOD load and trimmed on residual nutrient in the effluent — enough to feed the bugs, not so much that you breach an ammonia or phosphate limit. See the process context in biological treatment.
| Reagent | Supplies | Notes |
|---|---|---|
| Urea | Nitrogen | Cheap, safe, slow-release as it hydrolyses to ammonia |
| Ammonia / ammonium sulphate | Nitrogen | Fast-available N; handle with care |
| Phosphoric acid | Phosphorus | Readily available P; also trims pH |
| DAP (diammonium phosphate) | Nitrogen + Phosphorus | Single reagent supplying both; dosed as solution |
| Proprietary micronutrient blends | Trace metals (Fe, Co, Ni…) | For deficient feeds & anaerobic digesters |
Dose tracks the organic load (flow × COD/BOD), not just flow — so nutrients match what the biomass is actually eating.
Effluent ammonia/phosphate residual trims the dose — target a small residual to confirm the bugs aren't starved.
Dosed into the balance tank or aeration inlet for rapid, even mixing into the biomass.
Diaphragm pumps for solutions; materials chosen for the reagent — phosphoric acid needs acid-resistant wetted parts.
Max-dose limits stop nutrient dosing pushing effluent N or P over consent — the opposite failure mode to starvation.
Regular jar/lab checks of the BOD:N:P ratio confirm the programme — see calibration & verification.
Send us the influent BOD, N and P — we will calculate the nutrient deficit, choose the reagents and design the dosing to balance the plant without breaching limits.
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Select the regulatory standard for your country — it sets which parameters we need for a compliance-aware process assessment.
Required parameters for the chosen standard are flagged on the sample form. You can still submit a partial set and we will advise what else to test.
Your sample is stored against your company so we can track the project. Provide a company name or email as a minimum.