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This study evaluated and compared the performance of three highly praised high rate anaerobic bioreactors (HRABs), including the expanded granular sludge bed (EGSB) bioreactor, the static granular bed reactor (SGBR), and the down-flow expanded granular bed reactor (DEGBR), for the treatment of poultry slaughterhouse wastewater (PSW) which is characterized by a high concentration in oil and grease, suspended solids, and nutrients. These three bioreactors were operated under mesophilic conditions and followed a similar operational methodology, which consisted of increasing the organic loading rate (OLR) as the bioreactor responded positively to fluctuating organic loads. The response to the fluctuations of the bioreactors was evaluated with respect to the removal of the organic matter contained in PSW at high throughput rate. This study revealed that the three bioreactors performed differently. This dissimilarity in performance was associated with the difference in the configuration of each reactor and the capacity of maintaining a high performance at increased levels of OLR. These configurations are specifically described in this study. Of the three bioreactors that were investigated, the DEGBR performed the best with total chemical oxygen demand (tCOD), biological oxygen demand (BOD5) and fats, oil, and grease (FOG) maximum removal percentages of 99.6%, 99.9% and 99.4%, respectively, for a maximum OLR of 38.9 gCOD/L.day. While the EGSB also provided appreciable results with 99.1%, 99.5% and 97%, for the maximum removal efficiency of tCOD, BOD5 and FOG, respectively. At last, the SGBR achieved tCOD, BOD5 and FOG maximum percentage removal of 97.6%, 99.2% and 97.7%, respectively.

The treatment of poultry slaughterhouse wastewater (PSW) with an Expanded Granular Sludge-Bed Bioreactor (EGSB) is hindered by the washout of activated sludge, and difficulties associated with the operation of the three-phase separator and the determination of the optimum up-flow velocity for sludge-bed fluidization. This results in a poor reactor functionality, and thus a poor performance due to pollutants such as fats, oil and grease (FOG) in the PSW being treated. Hydrolyzing the FOG content with a bio-delipidation, enzyme-based agent in a pre-treatment unit would significantly improve the effectiveness of the primary PSW treating system, i.e., the EGSB. In this study, PSW was pre-treated for 48 h with a biological mixture containing bioflocculants and bio-delipidation constituents. The pre-treated PSW was further treated in an EGSB. The PSW FOG, total chemical oxygen demand (tCOD) and total suspended solids (TSS) content were determined to assess the effectiveness of the pre-treatment process as well as to observe the remedial action of the combined pre-treatment-EGSB system. An increased treatment efficacy was noted for the combined PSW treatment system, whereby the tCOD, FOG and TSS removal averaged 76%, 88% and 87%, respectively. The process developed is intended for micro, small and medium poultry slaughterhouses.

This paper assesses the performance of an integrated multistage laboratory-scale plant, for the treatment of poultry slaughterhouse wastewater (PSW). The system was comprised of an eco-flush dosed bio-physico pre-treatment unit for fats, oil, and grease (FOG) hydrolysis prior to the PSW being fed to a down-flow expanded granular bed reactor (DEGBR), coupled to a membrane bioreactor (DEGBR-MBR). The system’s configuration strategy was developed to achieve optimal PSW treatment by introducing the enzymatic pre-treatment unit for the lipid-rich influent (PSW) in order to treat FOG including odour causing constituents such as H2S known to sour anaerobic digestion (AD) such that the PSW pollutant load is alleviated prior to AD treatment. This was conducted to aid the reduction in clogging and sludge washout in the DEGBR-MBR systems and to achieve the optimum reactor and membrane system performance. A performance for the treatment of PSW after lipid reduction was conducted through a qualitative analysis by assessing the pre- and post-pre-treatment units’ chemical oxygen demand (COD), total suspended solids (TSS), and FOG concentrations across all other units and, in particular, the membrane units. Furthermore, a similar set-up and operating conditions in a comparative study was also performed. The pre-treatment unit’s biodelipidation abilities were characterised by a mean FOG removal of 80% and the TSS and COD removal reached 38 and 56%, respectively. The final acquired removal results on the DEGBR, at an OLR of ~18–45 g COD/L.d, was 87, 93, and 90% for COD, TSS, and FOG, respectively. The total removal efficiency across the pre-treatment-DEGBR-MBR units was 99% for COD, TSS, and FOG. Even at a high OLR, the pre-treatment-DEGBR-MBR train seemed a robust treatment strategy and achieved the effluent quality set requirements for effluent discharge in most countries.

The first step towards selecting a suitable treatment option for poultry slaughterhouse wastewater (PSW) treatment is to characterize it. Various parameters such as the pH, tCOD, BOD5, TSS, FOG, turbidity, salinity or conductivity were analyzed in this study and provided values significantly higher than discharge limits imposed by various countries. Furthermore, the biodegradability index (BOD5/COD) of PSW was determined and averaged a value of 0.61 for the samples collected during normal processing operations in the slaughterhouse and 0.72 for samples collected during the cleaning of equipment after broiler processing operations. This good biodegradability translated to a good biological decomposition potential, which can be a risk for the environment as a result of untreated effluent, and also highlights the suitability of biological treatment processes for the treatment of such wastewater. Moreover, to reduce the production of chemical waste from the toxic reagents used for some analyses, and to alleviate the cost and the time required for these analyses, linear regressions were used to correlate three water quality parameters (tCOD, BOD5, and FOG), interchangeably. These linear regressions provided a good relationship between these parameters, with R2 > 0.9 for the samples collected during normal operation periods; and weaker correlation for the FOG/BOD5 and FOG/tCOD of samples collected during the cleaning of processing equipment. This was attributed to the high concentration of FOG (5,216 ± 2,534) in the samples collected during this period, from the collection of carcass debris and fats left on the equipment during the slaughtering.

This study evaluated the performance of a novel high rate anaerobic bioreactor system for the treatment of poultry slaughterhouse wastewater (PSW). The new system consisted of a granule-based technology operated in a down-flow configuration, with the assistance of medium-sized pumice stones used as packing materials for the retention of the anaerobic granules, to avoid challenges associated with the use of the three-phase separator of up-flow systems and the washout of the anaerobic biomass. Furthermore, a recycling stream was applied to the system to improve the mixing inside the Down-flow Expanded Granular Bed Reactor (DEGBR), i.e. the influent distribution to the granular biomass, and the implementation of intermittent fluidization when required to alleviate the effects of pressure drop in such systems. The DEGBR was operated under mesophilic conditions (30–35 °C) and achieved total chemical oxygen demand (tCOD), five-day biological oxygen demand and total suspended solids average removal percentages >95%, and a fats, oils and grease average removal percentage of 93.67% ± 4.51, for an organic loading rate varying between 1.1 to 38.9 gCOD/L.day.

The poultry slaughterhouse industry consumes a large volume of potable water for bird processing and equipment cleaning, which culminates in the generation of high strength poultry slaughterhouse wastewater (PSW). The wastewater contains high concentrations of organic matter, suspended solids, nitrogen and nutrients. Most poultry slaughterhouses in South Africa (SA) discharge their wastewater into the municipal sewer system after primary treatment. Due to its high strength, PSW does not meet SA's industrial discharge standards. Discharge of untreated PSW to the environment raises environmental health concerns due to pollution of local rivers and fresh water sources, leading to odour generation and the spread of diseases. Thus, the development of a suitable wastewater treatment process for safe PSW discharge to the environment is a necessity. In this study, a biological PSW treatment process using an Expanded Granular Sludge Bed (EGSB) was evaluated. Response surface methodology coupled with central composite design was used to optimize the performance of the EGSB reactor. The dependant variable used for optimization was chemical oxygen demand (COD) removal as a function of two independent variables, hydraulic retention time (HRT) and organic loading rate (OLR). The interactions between HRT, OLR and COD removal were analysed, and a two factorial (2FI) regression was determined as suitable for COD removal modelling. The optimum COD removal of 93% was achieved at an OLR of 2 g-COD/L/d and HRT of 4.8 days. The model correlation coefficient (R2) of 0.980 indicates that it is a good fit and is suitable for predicting the EGSB's COD removal efficiency.

Poultry slaughterhouses consume a substantial quantity of potable water during processing of live birds. Subsequently, high strength poultry slaughterhouse wastewater (PSW) is generated at different stages during poultry product processing. In this study, a Static Granular Bed Reactor (SGBR) was used to treat the PSW from a poultry processing facility in the Western Cape, South Africa. The performance of the SGBR was primarily evaluated for chemical oxygen demand (tCOD) removal with the kinetics of the treatment process for PSW being evaluated using both the Grau second-order and the modified Stover-Kincannon models to predict the effluent COD. The overall treatment efficiency averaged >80% when the SGBR was operated at steady state for 110 days' experimental trial. On the basis of the experimental results, the predicted values of the tCOD concentration using the Grau second-order and modified Stover Kincannon model were inconsistent with the experimental data indicating an insignificant correlation with predicted tCOD concentration being higher than the experimental data. The high variation between the modelled and experimental data based on both the Grau second order and modified Stover-Kincannon model was observed at higher organic loading rates when the reactor was fed with undiluted influent, phenomena attributed to tCOD entrapped inside the SGBR, especially during periods of clogging caused by the accumulation of suspended solids in the underdrain.

This study presents the biological treatment of poultry slaughterhouse wastewater (PSW) using a combination of a biological pretreatment stage, an expanded granular sludge bed reactor (EGSB), and a membrane bioreactor (MBR) to treat PSW. This PSW treatment was geared toward reducing the concentration of contaminants present in the PSW to meet the City of Cape Town (CoCT) discharge standards and evaluate an alternative means of treating medium- to high-strength wastewater at low cost. The EGSB used in this study was operated under mesophilic conditions and at an organic loading rate (OLR) of 69 to 456 mg COD/L·h. The pretreatment stage of this laboratory-scale (lab-scale) plant played an important role in the pretreatment of the PSW, with removal percentages varying between 20% and 50% for total suspended solids (TSS), 20% and 70% for chemical oxygen demand (COD), and 50% and 83% for fats, oil, and grease (FOG). The EGSB further reduced the concentration of these contaminants to between 25% and 90% for TSS, 20% and 80% for COD, and 20% and &gt, 95% for FOG. The last stage of this process, i.e., the membrane bioreactor (MBR), contributed to a further decrease in the concentration of these contaminants with a peak removal performance of &gt, 95% for TSS and COD and 80% for the FOG. Overall, the system (pretreatment–EGSB–MBR) exceeded 97% for TSS and COD removal and 97.5% for FOG removal. These results culminated in a product (treated wastewater) meeting the discharge standards.

The process of anaerobic digestion has been and still remains the most efficient, cost effective and environmentally benign treatment process for poultry slaughterhouse wastewater (PSW). The PSW is characterized by a high concentration in chemical oxygen demand (COD), biological oxygen demand (BOD) and fats, oil including grease (FOG). The reactor configuration influences the performance of such anaerobic systems in the treatment of such oily wastewater. The up-flow reactor configuration provided by the Up-flow Anaerobic Sludge Blanket (UASB) Bioreactor or the Expanded Granular Sludge Bioreactor (EGSB) are highly dependent on up-flow velocity, which often contributes to periodical sludge washout during the treatment of PSW with high FOG and total suspended solids (TSS) concentration, resulting in poor reactor performance in comparison with downflow reactors such as the Static Granular Bed Reactor (SGBR), which achieves high organic load removal efficiency particularly when treating PSW due to its ability to retain sludge granules and solidified residue within the reactor. The washout of the sludge results from sludge flotation, which is induced by the inhibition of the anaerobic granular biomass by the accumulation of long chain fatty acids (LCFAs) from poor hydrolysis. The aim of this review is to highlight reactor configuration deficiencies, and to elaborate on the advantages of using anaerobic digestion for the treatment of FOG-laden PSW, with a focus on reactor performance. Additionally, a comparative analysis between up-flow reactors, such as the UASB including EGSB, and downflow reactors, such as SGBR, was performed.

Poultry slaughterhouse wastewater (PSW) with a high fats, oil, and grease (FOG) content in South Africa (SA) is generally discharged into municipal wastewater systems. This is detrimental for municipal treatment plants since there is a limited number of these wastewater treatment works (WWTWs) that are operating optimally. Furthermore, increasingly stringent standards for effluent discharge have placed an urgency on the development of advanced wastewater treatment technologies. This study evaluated the performance of a lab-scale integrated multi-stage PSW treatment system consisting of an aerobic pre-treatment tank, an expanded granular sludge bed (EGSB) bioreactor coupled with a submerged ultrafiltration (UF) membrane. The possibility of treating PSW to a water quality standard compliant with discharge by-laws or the standards of effluent discharge was investigated. The EGSB was operated for 120 days at a hydraulic retention time (HRT) of 5.71 h and an organic loading rate (OLR) ranging from 200 to 700 mg COD/L·h, while the submerged membrane unit had OLR fluctuating between 50 and 450 mg COD/L·h. The integrated system achieved overall average removal efficiencies (REs) of 98% for chemical oxygen demand (COD), 97% for FOG, and 99% for total suspended solids (TSS); and reducing the pollutant content of the treated PSW to 101 mg/L COD, 8 mg/L FOG and 7 mg/L TSS, i.e. qualities which are comparable to inland surface water, rendering it safe for discharge into the City of Cape Town (CCT) WWTWs.

Biological wastewater treatment processes such as activated sludge and anaerobic digestion remain the most favorable when compared to processes such as chemical precipitation and ion exchange due to their cost-effectiveness, eco-friendliness, ease of operation, and low maintenance. Since Abattoir Wastewater (AWW) is characterized as having high organic content, anaerobic digestion is slow and inadequate for complete removal of all nutrients and organic matter when required to produce a high-quality effluent that satisfies discharge standards. Multi-integrated systems can be designed in which additional stages are added before the anaerobic digester (pre-treatment), as well as after the digester (post-treatment) for nutrient recovery and pathogen removal. This can aid the water treatment plant effluent to meet the discharge regulations imposed by the legislator and allow the possibility for reuse on-site. This review aims to provide information on the principles of anaerobic digestion, aeration pre-treatment technology using enzymes and a hybrid membrane bioreactor, describing their various roles in AWW treatment. Simultaneous nitrification and denitrification are essential to add after anaerobic digestion for nutrient recovery utilizing a single step process. Nutrient recovery has become more favorable than nutrient removal in wastewater treatment because it consumes less energy, making the process cost-effective. In addition, recovered nutrients can be used to make nutrient-based fertilizers, reducing the effects of eutrophication and land degradation. The downflow expanded granular bed reactor is also compared to other high-rate anaerobic reactors, such as the up-flow anaerobic sludge blanket (UASB) and the expanded granular sludge bed reactor (EGSB).

The South African poultry industry has grown exponentially in recent years due to an increased demand for their products. As a result, poultry plants consume large volumes of high quality water to ensure that hygienically safe poultry products are produced. Furthermore, poultry industries generate high strength wastewater, which can be treated successfully at low cost using anaerobic digesters. In this study, the performance of a bench-scale mesophilic static granular bed reactor (SGBR) containing fully anaerobic granules coupled with an ultrafiltration (UF) membrane system, as a post-treatment system, was investigated. The poultry slaughterhouse wastewater was characterized by a chemical oxygen demand (COD) range between 1,223 and 9,695mg/L, average biological oxygen demand of 2,375mg/L and average fats, oil and grease (FOG) of 554mg/L. The SGBR anaerobic reactor was operated for 9 weeks at different hydraulic retention times (HRTs), i.e. 55 and 40 h, with an average organic loading rate (OLR) of 1.01 and 3.14g COD/L.day. The SGBR results showed an average COD, total suspended solids (TSS) and FOG removal of 93%, 95% and 90% respectively, for both OLR. The UF post-treatment results showed an average of COD, TSS and FOG removal of 64%, 88% and 48%, respectively. The overall COD, TSS and FOG removal of the system (SGBR and UF membrane) was 98%, 99.8%, and 92.4%, respectively. The results of the combined SGBR reactor coupled with the UF membrane showed a potential to ensure environmentally friendly treatment of poultry slaughterhouse wastewater.

In this study, the efficiency of an anaerobic treatment system for wastewater from a South African poultry slaughterhouse was evaluated using a lab-scale static granular bed reactor (SGBR). The down-flow SGBR (2 L) was operated continuously for 138 days under mesophilic conditions (35-37 ˚C), at hydraulic retention times (HRTs) ranging from 24 to 96 h and average organic loading rates (OLRs) of 0.78 to 5.74 g COD/L.day. The SGBR achieved an average chemical oxygen demand (COD) removal efficiency of 80% and the maximum COD removal achieved was 95%, at an HRT of 24 h and average OLR of 5.74 g COD/L.day. The optimization of the SGBR, with regard to a suitable HRT and OLR, was determined using response surface methodology (RSM). The optimal SGBR performance with regard to the maximum COD removal efficiency was predicted for an OLR of 12.49 g COD/L.day and a HRT of 24 h, resulting in a 95.5% COD removal efficiency. The model R2 of 0.9638 indicated that the model is a good fit and is suitable to predict the COD removal efficiency for the SGBR.

Poultry slaughterhouses consume a substantial quantity of clean water during processing of live birds. Subsequently, high strength poultry slaughterhouse wastewater (PSW) is generated at different stages during poultry product processing. In this study, Static Granular Bed Reactor (SGBR) was used to treat the PSW from a poultry product processing facility in the Western Cape, South Africa. The performance of the SGBR was primarily evaluated for chemical oxygen demand (COD) removal with the kinetics of the treatment process of the PSW being evaluated using the modified Stover-Kincannon and the Grau second order models. Overall, the treatment efficiency averaged >90% when the SGBR were operated at steady state for a 68 days experimental trial. Furthermore, both the Grau second-order and the modified Stover-Kincannon models were used to develop a kinetic model which sufficiently described the COD removal. The Grau second-order model produced a better fit (R2 > 0.99) when compared to the Stover-Kincannon model (R2 > 0.80). The kinetic relationship derived from the lab-scale SGBRs can thus be used to predict the performance of the pilot scale SGBRs treating the PSW under mesophilic conditions.

This study evaluated the performance of a lab-scale poultry slaughterhouse wastewater (PSW) treatment system consisting of a static granular bed reactor (SGBR) coupled with single stage nitrification-denitrification (SND) bioreactor and ultrafiltration membrane module (ufMM) systems. The feasibility of treating PSW to a water quality standard compliant with industrial wastewater discharge standards was investigated. The SGBR was operated at hydraulic retention times (HRTs) ranging from 24 to 96 h and organic loading rates (OLRs) ranging from 0.73 to 12.49 g COD/L.day, for 138 days. The chemical oxygen demand (COD), total suspended solids (TSS), biological oxygen demand (BOD5) and fats, oils and grease (FOG) removal efficiencies achieved by the SGBR averaged 80%, 95%, 89% and 80%, respectively. The SND bioreactor achieved total nitrogen (TN) removal efficiencies of 33% and 79% for the SGBR effluent, when operated in down-flow mode without aeration and up-flow mode with aeration, respectively. The ufMMs, operated in dead-end filtration mode, were able to further reduce the COD and TSS by an average of 65% and 54%, respectively. The results for the PSW treatment system demonstrated the combined benefits of biological and physical treatment processes, with averaged COD, ortho-phosphate (PO43−-P), TSS and total dissolved solids (TDS) removal efficiencies of 91%, 51%, 97% and 52%, respectively, being achieved over 52 days. The final effluent was deemed suitable for discharge; although, the PO43- and NH4+-N requires further monitoring and the PSW treatment system design requires refinement.