Poultry farming is among the agro-industrial sectors with the highest water demand, both for raising birds and for slaughtering and processing. Water plays a fundamental role throughout the production chain from drinking water supply and ensuring animal welfare in poultry houses to intensive use during slaughter and carcass processing. In slaughterhouses, water is extensively used to ensure food safety and compliance with strict sanitary regulations, including processes such as initial washing, feather removal, evisceration, carcass chilling, and the cleaning of equipment, work surfaces, and transportation vehicles [1]. It is estimated that approximately 30 liters of water are required per bird slaughtered. This high consumption is primarily due to stringent food safety standards, particularly for export-oriented production. However, it results in large volumes of effluents rich in organic matter, nutrients, chemical substances, and pathogens, which require appropriate treatment before discharge to prevent contamination of water resources [2]. Effluent treatment, especially for those with high organic loads such as poultry slaughterhouse wastewater, involves a combination of physical-chemical and biological processes to effectively remove pollutants and comply with environmental regulations. Treatment typically begins with the physical separation of solids like feathers and fragments through screening, followed by oil and grease removal via coagulation/flocculation, where lighter particles are captured and removed from the surface [3].

Subsequently, biological treatment is applied, in which microorganisms degrade organic matter in the effluent. This process can occur under aerobic conditions where oxygen is supplied to enhance microbial activity or anaerobic conditions, without the presence of oxygen. Following these steps, the effluent is directed to stabilization ponds (natural or artificial), which are large reservoirs that employ natural degradation mechanisms to further reduce organic loads and nutrient concentrations. These ponds utilize microbial activity, sunlight, and sedimentation to improve water quality, enabling its discharge into receiving water bodies [4]. Given the high water demand in poultry slaughterhouses, water reuse has become a viable strategy for promoting sustainability, optimizing operational processes, and reducing costs. Beyond economic and environmental advantages, the adoption of water reuse also enhances the company’s environmental image, reflecting a commitment to water resource conservation. In this context, water that has undergone treatment, including stabilization pond processes, can potentially be reused [5,6].

In Brazil, water reuse in poultry slaughterhouses is permitted for non-potable purposes, such as floor cleaning, irrigation, and equipment cooling, provided there is no contact with carcasses or food products. This practice is regulated by the Brazilian Ministry of Agriculture’s Normative Instruction nº 51/2020 [7], and water quality must comply with the microbiological standards established by Ordinance GM/MS nº 888/2021[8]. Resolution CONAMA nº 430/2011 [9], is also referenced for treated water quality. Potable reuse or reuse involving direct contact with food products requires advanced treatment and prior approval by the relevant authorities. Furthermore, applicable state and municipal regulations must be observed. To ensure the safety and viability of water reuse, adequate treatment of the collected water is essential. In this regard, membrane technologies have emerged as efficient and modern alternatives for improving effluent quality. According to [10], membrane systems offer several advantages, including continuous operation under ambient conditions, reduced space requirements, and the potential for water reuse. Among these, ultrafiltration membranes stand out, with pore sizes ranging from 0.01 to 0.1 micrometers (10–100 nanometers), allowing the passage of water and small solutes while retaining larger particles, microorganisms, and colloids [11]. Therefore, integrating membrane processes after stabilization ponds may enhance effluent quality, making it suitable for broader reuse applications. As awareness grows around sustainable water management, the implementation of advanced technologies such as ultrafiltration becomes essential for promoting environmental responsibility within the poultry industry, contributing to a more sustainable and lower-impact future.

This study aims to evaluate the use of ultrafiltration membrane as a technological alternative for the treatment of poultry slaughterhouse effluents for reuse purposes. The performance of the ultrafiltration process under different operational conditions was assessed, and the physicochemical and microbiological quality of the membrane permeates was analyzed.

Effluent Samples

The effluent was provided by a poultry slaughterhouse located in the northern region of Rio Grande do Sul, Brazil. Samples were collected after tertiary treatment in a stabilization pond, using 5-liter plastic containers that were properly sealed and labeled. The samples were then transported to the Regional Integrated University of the Missions (URI) – Erechim campus, where they were frozen and stored in a freezer at -18ºC (±1) (Consul, CVU30) until analysis.

Figure 1: Hollow fiber membrane separation system.

Where: Feed (A), pressure gauge (B), pressure adjustment (C), concentrate flow (D), hollow fiber membrane module (E), feed pump controller (F), permeate fraction (G), concentrate fraction (H), feed pump (I).

Ultrafiltration Membrane Experiments for Effluent Treatment

Permeate fluxes were evaluated using distilled water and filtered effluent in triplicate, obtained by measuring the permeate volume relative to the membrane area and operating time. The tests were conducted at room temperature (20°C ± 3). The hollow fiber membrane used was made of polysulfone, supplied by TECNAL, with a 50,000 NMWC (Nominal Molecular Weight Cut-off) and an area of 1400 cm². The raw effluent, filtered effluent, and permeates were assessed for their physicochemical and microbiological characteristics.

After each experiment with the effluent, conducted under different pressures, membrane cleaning was performed to remove accumulated residues and preserve performance. The adopted protocol used the same pressure applied in the respective filtration test, with a constant feed flow rate and room temperature. The cleaning procedure consisted of the following steps: First, a pre-rinse with 5 L of distilled water was carried out to remove loosely bound surface residues, followed by alkaline cleaning, achieved by circulating distilled water with pH adjusted to 11 using a 7% (w/v) sodium hydroxide solution for 30 min. Subsequently, 5 mL of sodium hypochlorite was added to the previously used alkaline solution, maintaining circulation for an additional 30 min, followed by a distilled water rinse. Finally, 5 L of distilled water was circulated for 15 min to ensure the removal of chemical residues and membrane stabilization. The need for hypochlorite or alkaline cleaning agents to restore flux, as reported by [12], justifies the standardized cleaning protocol adopted in this study. This procedure was repeated in a standardized manner after all trials, ensuring proper conditions for membrane reuse in subsequent tests.

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