From City Wastewater
to Farm Water
A circular solution for water-scarce cities: we treat the city's wastewater and carry it to the field, while returning the sludge to the soil. We bring our discipline from industrial treatment to the city scale.
Circular Water at City Scale
GESU's identity was shaped in industrial wastewater treatment: an engineering culture that treats the most challenging process waters and designs and manufactures its own equipment. Today we bring that discipline to the city scale.
Municipal water reuse aims not only to discharge a city's wastewater without harming the environment, but to turn it into a resource that adds value to agriculture. Through a five-link chain, wastewater becomes irrigation water and sludge becomes a soil conditioner.
The Reuse Chain
A five-link flow that runs from municipal wastewater to farm water and a soil conditioner.
Municipal WWTP — Biological Treatment
What happens
After pre-treatment (screening, grit and grease removal), biological treatment removes organic load, nitrogen and phosphorus. The population's domestic wastewater becomes a stable treated water.
GESU's role
Process design, equipment manufacturing (screens, diffusers, mixers, clarifiers) and installation. An integrated biological process under a single responsibility.
Typical output
Advanced biological treatment typically achieves BOD < 20 mg/L, COD < 100 mg/L; with nutrient removal, total N and P are reduced to limit values.
MBR — Tertiary Membrane Treatment
What happens
The membrane bioreactor combines biological treatment with membrane filtration. Suspended solids and most pathogens are retained at the physical barrier, producing clear permeate.
GESU's role
With the BIOSU MBR product family: membrane cassette selection, process integration and automation. Can also be added as a tertiary stage onto an existing WWTP.
Typical output
MBR permeate typically achieves BOD < 5 mg/L, turbidity < 0.2 NTU and near-zero suspended solids — a quality baseline suitable for irrigation.
Disinfection
What happens
UV, chlorination or a combination reduces the remaining microbiological risk to the targeted water quality class, providing a safety margin appropriate to the irrigation method.
GESU's role
Design of the disinfection unit, dosing and measurement automation. Thanks to the MBR barrier, the target is reached with a lower disinfectant dose.
Typical output
Water compliant with the E. coli / pathogen limits set by reuse guidelines and safe for irrigation. Target values are set by crop and class.
Direct Agricultural Irrigation
What happens
The treated and disinfected water is carried to agricultural areas through storage and distribution. Drip or surface irrigation is planned according to the selected quality class.
GESU's role
Design of storage, pumping and conveyance of the reclaimed water; quality-monitoring integration. A sustainable irrigation source instead of mains water.
Typical output
Irrigation water that partly retains plant nutrients (N, P) and reduces freshwater demand. Total recovery is typically based on 90%+ MBR permeate yield.
Sludge Dewatering + Composting
What happens
Biological sludge is first dewatered (belt press, decanter or filter press), then stabilized through controlled aerobic composting.
GESU's role
Manufacturing of dewatering equipment, polymer dosing system and process design of the composting yard. We position sludge as a resource, not a cost.
Typical output
Typically 20-30% dry solids in dewatering; after composting, a soil conditioner / organic fertilizer whose compliance with regulation is verified.
Reuse Standards
We base agricultural reuse on international frameworks and design in compliance with local regulation. The following is general information.
WHO / FAO Reuse Guidelines
- An international framework for the safe use of wastewater in agriculture.
- A multi-barrier approach: treatment + irrigation method + crop selection are assessed together.
- Prioritizes risk management through health-based targets.
EU 2020/741 Water Reuse Regulation
- Classifies reclaimed water for agricultural irrigation into quality classes A, B, C and D.
- Class A, the highest quality, allows all irrigation methods for crops eaten raw.
- Classes B-C-D target processed crops, fodder and industrial crops with more restricted irrigation methods.
- Defines microbiological and physico-chemical monitoring requirements for each class.
Local Regulatory Compliance
Every project is designed according to the wastewater discharge and reuse regulation of the country where the plant is located. We take international guidelines as the baseline and build monitoring infrastructure that meets local permitting processes and inspection requirements.
Why GESU?
We carry the discipline matured in industrial treatment to the city scale, under a single responsibility.
Vertical Integration
Process know-how, our own manufacturing and installation under one roof. A single responsibility from design to commissioning.
30 Years of Industrial Discipline
We apply the engineering discipline earned on the toughest industrial process waters to the city scale.
Experience in 17 Countries
Project experience across varied climates, regulations and site conditions — the ability to adapt to international plants.
BIOSU MBR Product Family
Our membrane bioreactor solutions deliver clear, irrigation-ready permeate in tertiary treatment.
Frequently Asked Questions
Is MBR-treated water safe for agricultural irrigation?
MBR permeate retains suspended solids and, to a large extent, pathogens thanks to the physical barrier of the membrane. When supported by appropriate disinfection (UV or chlorine), the water quality classes defined by WHO/FAO guidelines and the EU 2020/741 regulation according to crop type and irrigation method can be achieved. The quality target is set project by project based on the crop and irrigation method.
Which crops can reclaimed water be used for?
In international frameworks, the range of use widens as the water quality class rises. In general, the highest class water can be used for drip irrigation of crops eaten raw, while lower classes are used for processed crops, fodder crops and industrial crops. The final use should be determined together with local regulation and agronomic advice.
How does the sludge composting process work?
Sludge from biological treatment is first dewatered (belt press, decanter or filter press), then mixed with a suitable carbon source and placed into controlled aerobic composting. The product, stabilized by managing temperature, moisture and aeration, can be used as a soil conditioner or organic fertilizer once compliance with regulation is verified.
How much water can be recovered from municipal wastewater?
In MBR systems permeate yield is typically above 90%; the remainder goes to membrane cleaning and the sludge line. The total recovery rate varies depending on pre-treatment, climate and operating conditions. Values are literature-typical and are calculated with a mass balance for each project.
How are operating costs managed?
The main operating items are energy (aeration and membranes), membrane cleaning chemicals and periodic membrane replacement. Costs are kept under control with energy-efficient diffuser selection, aeration optimized through automation and a sound membrane operating strategy. The value of the reclaimed water and compost can partly offset operating cost.
Related Solutions
Municipal / Domestic Wastewater
Solutions for municipalities and residential settlements with BIOSU package plants.
ExploreIndustrial Water Reuse & ZLD
UF + RO recovery and zero liquid discharge at industrial scale — see the metal finishing page.
ExploreIndustrial Wastewater
GESU's core identity: industry-specific industrial treatment solutions.
ExploreLet's Talk About Your Municipal Reuse Project
With our industrial treatment discipline, let's design the most suitable solution for your municipal water reuse project together.