Food Processing Wastewater Research Articles

Photosynthetic bacteria production from food processing wastewater in sequencing batch and membrane photo-bioreactors

Application of photosynthetic process could be highly efficient and surpass anaerobic treatment in releasing less greenhouse gas and odor while the biomass produced can be utilized. The combination of photosynthetic process with membrane separation is possibly effective for water reclamation and biomass production. In this study, cultivation of mixed culture photosynthetic bacteria from food processing wastewater was investigated in a sequencing batch reactor (SBR) and a membrane bioreactor (MBR) supplied with infrared light. Both photo-bioreactors were operated at a hydraulic retention time (HRT) of 10 days. Higher MLSS concentration achieved in the MBR through complete retention of biomass resulted in a slightly improved performance. When the system was operated with MLSS controlled by occasional sludge withdrawal, total biomass production of MBR and SBR photo-bioreactor was almost equal. However, 64.5% of total biomass production was washed out with the effluent in SBR system. Consequently, the higher biomass could be recovered for utilization in MBR.

Kinetic modeling of granular activated carbon promoted ozonation of a food-processing secondary effluent

A mathematical model has been developed and applied to simulate the behavior of a chemical reactor for the ozonation of a food-processing secondary wastewater effluent in the presence of granular activated carbon (GAC). The reactor configuration comprises two compartments in series: a bubble column for gas (ozone)–liquid (wastewater) contact and a fixed bed column for solid (catalyst)–liquid (wastewater) reaction. Second order kinetics for both direct ozonation and heterogeneous catalytic ozonation has been considered in the kinetic approach. After rate constants determination, the kinetic model was validated by comparing simulated and experimental results at different operating conditions. The mathematical model accurately predicted experimental data and the influence of the studied operating variables in the ozone dose range 0–4g O3/g TOC. However, the model failed to predict experimental results when applying higher ozone doses, probably due to the changing nature of the oxidation state of the water matrix.

The investigation of dairy industry wastewater treatment in a biological high performance membrane system

The dairy industry is generally considered to be the largest source of food processing wastewater in many countries. The highly variable nature of dairy wastewaters in terms of volumes and flowrates and in terms of high organic materials contents such as COD 921–9004 mg L −1, BOD 483–6080 mg L −1, TN of 8–230 mg L −1 and SS of 134–804 mg L −1 makes the choice of an effective wastewater treatment regime difficult. A high performance bioreactor, an aerobic jet loop reactor, combined with a ceramic membrane filtration unit, was used to investigate its suitability for the treatment of the dairy processing wastewater. The oxygen transfer rates of the bioreactor were found to be very high (100–285 h −1) on the operating conditions. A loading rate of 53 kg COD m −3 d −1 resulted in 97–98% COD removal efficiencies under 3 h hydraulic retention time. The high MLSS concentrations could be retained in the system (up to 38,000 mg L −1) with the contribution of UF (ultrafiltration) unit. During the filtration of activated sludge, the fluxes decreased with increasing MLSS. Cake formation fouling was determined as dominant fouling mechanisms. The results demonstrate that jet loop membrane bioreactor system was a suitable and effective treatment choice for treating dairy industry wastewater.

Reduced membrane fouling in a novel bio-entrapped membrane reactor for treatment of food and beverage processing wastewater

A novel Bio-Entrapped Membrane Reactor (BEMR) packed with bio-ball carriers was constructed and investigated for organics removal and membrane fouling by soluble microbial products (SMP). An objective was to evaluate the stability of the filtration process in membrane bioreactors through backwashing and chemical cleaning. The novel BEMR was compared to a conventional membrane bioreactor (CMBR) on performance, with both treating identical wastewater from a food and beverage processing plant. The new reactor has a longer sludge retention time (SRT) and lower mixed liquor suspended solids (MLSS) content than does the conventional. Three different hydraulic retention times (HRTs) of 6, 9, and 12 h were studied. The results show faster rise of the transmembrane pressure (TMP) with decreasing hydraulic retention time (HRT) in both reactors, where most significant membrane fouling was associated with high SMP (consisting of carbohydrate and protein) contents that were prevalent at the shortest HRT of 6 h. Membrane fouling was improved in the new reactor, which led to a longer membrane service period with the new reactor. Rapid membrane fouling was attributed to increased production of biomass and SMP, as in the conventional reactor. SMP of 10–100 kDa from both MBRs were predominant with more than 70% of the SMP <100 kDa. Protein was the major component of SMP rather than carbohydrate in both reactors. The new reactor sustained operation at constant permeate flux that required seven times less frequent chemical cleaning than did the conventional reactor. The new BEMR offers effective organics removal while reducing membrane fouling.

Catholyte Performance as an Influencing Factor on Electricity Production in a Dual-chambered Microbial Fuel Cell Employing Food Processing Wastewater

Dual chambered, salt bridge microbial fuel cells (MFCs) with aerated catholyte (MFCAC), phosphate catholyte (MFCPC) were designed. The efficiency of catholytes on bioelectricity production and substrate removal were evaluated by employing food-processing wastewater as anolyte. Experimental results proved that MFCAC was better than MFCPCM by producing a maximum power density of 123.8 mW/m2, current density of 54.3 mA/m2, power yield of 110 mW/kg and COD removal of 98.9%.

Application of Fenton’s Reaction for Food-processing Wastewater Treatment

AbstractDepending on the process type and raw materials involved, various types of wastewater are discharged from food industry. In the present study the feasibility of Fenton-based treatment, as a part of combined treatment schemes, to degrade high organic content, to eliminate suspended solids, and to improve the overall quality of food-processing plant wastewater was assessed. Fenton oxidation step used in treatment schemes improved significantly the quality of the effluent, enabling additional 62-79% and 53-69% reduction of chemical oxygen demand (COD) and dissolved organic carbon (DOC), respectively, when the H

Effects of temperature and initial pH on biohydrogen production from food-processing wastewater using anaerobic mixed cultures

This study attempted to determine the optimal temperature and initial cultivation pH by conducting a series of batch tests in stirred-tank bioreactor using fructose-producing wastewater as an organic substrate. The bioreactor temperature was controlled at 35-55°C with an initial pH of 4-8. Hydrogen production efficiency was assessed using specific hydrogen production potential (SHPP) and the maximum specific hydrogen production rate (SHPR(m)). Experimental results indicated that temperature and initial pH markedly affected SHPP and SHPR(m), volatile fatty acids distribution as well as the ratio of butyrate/acetate (BHu/HAc). Two-fold higher SHPP and SHPR(m) were obtained at thermophilic condition (55°C) than those at mesophilic condition (35°C). The optimal initial pH was 6 for hydrogen production with peak values of SHPP of 166.8 ml-H(2)/g-COD and SHPR(m) of 26.7 ml-H(2)/g-VSS-h for fructose-processing wastewater. Molasses-processing wastewater had a higher SHPP (187.0 ml-H(2)/g-COD) and SHPR(m) (42.7 ml-H(2)/gVSS-h) than fructose-processing wastewater at pH 6. The DGGE profiles indicated that molasses-processing wastewater is a better substrate than fructose-processing wastewater for growth of hydrogen-producing bacteria due to the high staining intensity of bands.

Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor

A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume of 798 m(3) and can treat 33.3 m(3) wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes, the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the volumetric COD loading fluctuated in the range of 1.6-5.6 kg COD m(-3) day(-1), the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content of CH(4) in total biogas of the reactor were found to be 80.1 ± 5%, 0.2-0.5, 348.5 m(3 )day(-1) and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability of the system.

Sustainable Natural Systems for Treatment and Disposal of Food Processing Wastewater

This paper presents a state-of-the-art review of natural wastewater treatment technologies selected from the point of view of sustainability and relates them to feasible reuse and disposal practices available for food processing wastewater. Selected technologies include land application, constructed wetlands, and various pond systems that all make use of natural processes. The aim of the review is to help understand issues controlling wastewater reuse and how the different natural treatment systems and their combinations could help us to protect the environment, meet regulations, and conserve water, material, and energy resources.

Life Cycle Assessment of a Wastewater Treatment Plant Focused on Material and Energy Flows

Life cycle assessment (LCA) was applied to analyze a food-processing wastewater treatment plant and investigate the economic and environmental effects of the plant. With the long-term operational data of this plant, an inventory of relative inputs, e.g., flow rate, chemical oxygen demand (COD), and suspended solids, etc., and outputs of the plant, e.g., effluent COD and suspended solids, methane production, etc., was compiled. The potential environmental effects associated with those inputs and outputs were evaluated, and the results of the inventory analysis and impact assessment phases of the plant were interpreted. One feature of this study was the assessment of the treatment plant based on both energy and material flows. Another feature was the establishment of an assessment model with an integration of plant operating parameters, system recognition and grey relation. The analytical results are helpful for the design and operation of wastewater treatment plants.

Use of Filamentous Fungi for Wastewater Treatment and Production of High Value Fungal Byproducts: A Review

Conventional biological wastewater treatment generates large amounts of low value bacterial biomass. The treatment and disposal of this excess bacterial biomass, also known as waste activated sludge, accounts for about 40–60% of the wastewater treatment plant operation cost. A different form of biomass with a higher value could significantly change the economics of wastewater treatment. Fungi could offer this benefit over bacteria in wastewater treatment processes. The biomass produced during fungal wastewater treatment has, potentially, a much higher value than that from the bacterial activated sludge process. The fungi can be used to derive valuable biochemicals and can also be used as a protein source. Various high-value biochemicals are produced by commercial cultivation of fungi under aseptic conditions using expensive substrates. Food-processing wastewater is an attractive alternative as a source of low-cost organic matter and nutrients to produce fungi with concomitant wastewater purification. This review summarizes various findings in fungal wastewater treatment, particularly focusing on byproduct recovery during wastewater treatment. This review also provides an overview on performance of fungal treatment systems under various operational conditions. Important factors such as pH, temperature, hydraulic and solids retention time, nonaxenic and axenic operation, and others that affect the fungal treatment system are discussed. Moreover, certain important practical issues such as bacterial contamination under nonaseptic operation are also covered. The goal of the review paper is to evaluate the feasibility of cultivating fungi during wastewater treatment for deriving valuable biochemicals.

Hydrogen Production from Food Processing Wastewater – Case Study on Tofu Wastewater

Hydrogen Production from Food Processing Wastewater – Case Study on Tofu Wastewater

Kinetic evaluation and performance of a mesophilic anaerobic contact reactor treating medium-strength food-processing wastewater

High rate mesophilic anaerobic contact reactors (MACR) represent a proven sustainable technology for a wide range of different industrial effluents. These reactors demonstrate quite similar features to their aerobic counterparts, activated sludge systems. A lab-scale high rate mesophilic anaerobic contact reactor was operated with wastewater originated from a potato-processing plant, at six different loading rates of 1.1–5 g COD/L per day. The operational performance of MACR was monitored from start-up by assessing COD removal efficiency, total volatile fatty acid production and biogas composition. Furthermore, various kinetic models have been successfully applied to the experimental data to determine substrate balance, maximum utilization rate and volumetric methane production. The COD removal efficiencies were found to be 78–92% and the methane percentage of the biogas produced was 80–89%. Additionally, the methane yield coefficient was found to be 0.394 L CH 4/gTCOD rem.

Estimation of greenhouse gas generation in wastewater treatment plants – Model development and application

A comprehensive mathematical model has been developed to estimate greenhouse gas (GHG) emissions by wastewater treatment plants (WWTP) resulting from on-site and off-site activities. The contribution of individual processes to the production of GHGs in a typical hybrid treatment system for food processing wastewaters has been determined. The results show that the recovery of biogas and its reuse as fuel have a remarkable impact on GHG emissions and reduce the overall emissions by 1023 kg CO 2e d −1 from a total of 7640 kg CO 2e d −1 when treating a wastewater at 2000 kg BOD d −1. Furthermore, the recovery of biogas and its combustion may be used to cover the entire energy needs of the treatment plant for aeration, heating and electricity generation while creating emissions credit equal to 34 kg CO 2e d −1. The off-site GHG emissions resulting from the manufacturing of material for on-site usage were identified as the major source of GHG generation in hybrid treatment systems. These emissions account for the generation of 4138 kg CO 2e d −1, or 62% of the overall GHG emissions when biogas recovery is carried out. The inclusion of GHG emissions from nutrient removal as well as off-site processes in the overall GHG emissions of WWTPs increased the accuracy and completeness of this estimation, lending support to the novelty of the present study.

In Situ Detection and Quantification of Uncultured Members of the Phylum Nitrospirae Abundant in Methanogenic Wastewater Treatment Systems

In upflow anaerobic sludge blanket (UASB) reactors treating high-strength organic wastewaters, uncultured phylotypes belonging to the phylum Nitrospirae were assumed to play a key role in the treatment processes because of their high abundance as determined by 16S rRNA gene-based clone library analyses (Narihiro et al. (27)). A comparative nucleotide sequence analysis of the phylotypes, commonly found in anaerobic mesophilic sludges, revealed that these phylotypes formed a coherent clade at the family to genus levels with no cultured representatives. To determine the abundance and distribution in methanogenic waste/wastewater treatment sludges, 16S rRNA gene-based quantitative PCR measurements and 16S rRNA-targeted fluorescence in situ hybridization (FISH) were carried out. A specific gene primer/probe for the uncultured clade was developed and used for quantitative PCR and in situ detection of the targeted cells within the sludge granules. In all the six UASB sludges treating food-processing organic wastewaters, the phylotypes were detected at a range of 0.1 to 10.9% of total 16S rRNA genes. FISH revealed that the gene probe reacted with coccoid or irregular coccoid-like cells in the middle and inner layers of sludge granules of a UASB reactor, in which the Nitrospirae phylotypes were found in abundance by real-time PCR analyses.

The use constructed wetlands with horizontal sub-surface flow for various types of wastewater

Constructed wetlands with horizontal sub-surface flow (HF CWs) have been used for wastewater treatment for more than 30 years. Most HF CWs have been designed to treat municipal or domestic wastewater. Nowadays, municipal HF CWs focus not only on common pollutants but also on special parameters such as pharmaceuticals, endocrine disruptive chemicals or linear alkylbenzensulfonates (LAS). At present, HF CWs are used to treat many other types of wastewater. Industrial applications include wastewaters from oil refineries, chemical factories, pulp and paper production, tannery and textile industries, abattoir, distillery and winery industries. In particular, the use of HF CWs is becoming very common for treatment of food-processing wastewaters (e.g., production and processing of milk, cheese, potatoes, sugar). HF constructed wetlands are also successfully used to treat wastewaters from agriculture (e.g., pig and dairy farms, fish farm effluents) and various runoff waters (agriculture, airports, highway, greenhouses, plant nurseries). HF CWs have also effectively been used to treat landfill leachate. Besides the use as a single unit, HF CWs are also used in combination with other types of constructed wetlands in hybrid systems.

Environmental Impacts and Sustainability of Degraded Water Reuse

Greater urban demand for finite water resources to meet domestic, agricultural, industrial, and recreational needs; increased frequency of drought resulting from erratic weather; and continued degradation of available water resources from point and nonpoint sources of pollution have focused attention on the reuse of degraded waters as a potential water source. However, short- and long-term detrimental environmental impacts and sustainability of degraded water reuse are not well known or understood. These concerns led to the organization of the 2007 ASA-CSSA-SSSA Symposium entitled Environmental Impacts and Sustainability of Degraded Water Reuse. Out of this symposium came a special collection of 4 review papers and 12 technical research papers focusing on various issues associated with the reuse of agricultural drainage water, well water generated in the production of natural gas from coalbeds, municipal wastewater and biosolids, wastewater from confined animal operations, urban runoff, and food-processing wastewater. Overviews of the papers, gaps in knowledge, and future research directions are presented. The future prognosis of degraded water reuse is promising, provided close attention is paid to managing constituents that pose short- and long-term threats to the environment and the health of humankind.

Modeling Vadose Zone Processes during Land Application of Food‐Processing Waste Water in California's Central Valley

Land application of food-processing waste water occurs throughout California's Central Valley and may be degrading local ground water quality, primarily by increasing salinity and nitrogen levels. Natural attenuation is considered a treatment strategy for the waste, which often contains elevated levels of easily degradable organic carbon. Several key biogeochemical processes in the vadose zone alter the characteristics of the waste water before it reaches the ground water table, including microbial degradation, crop nutrient uptake, mineral precipitation, and ion exchange. This study used a process-based, multi-component reactive flow and transport model (MIN3P) to numerically simulate waste water migration in the vadose zone and to estimate its attenuation capacity. To address the high variability in site conditions and waste-stream characteristics, four food-processing industries were coupled with three site scenarios to simulate a range of land application outcomes. The simulations estimated that typically between 30 and 150% of the salt loading to the land surface reaches the ground water, resulting in dissolved solids concentrations up to sixteen times larger than the 500 mg L(-1) water quality objective. Site conditions, namely the ratio of hydraulic conductivity to the application rate, strongly influenced the amount of nitrate reaching the ground water, which ranged from zero to nine times the total loading applied. Rock-water interaction and nitrification explain salt and nitrate concentrations that exceed the levels present in the waste water. While source control remains the only method to prevent ground water degradation from saline wastes, proper site selection and waste application methods can reduce the risk of ground water degradation from nitrogen compounds.

A Study of Microbial Fuel Cell Using Wheat Bran

In recent years, recycling of organic waste has been needed in Japan. To make biogas and compost are usual ways of the recycling today. And a microbial fuel cell (MFC), a direct generator using microorganism from organic and inorganic compounds, has been investigated recently. Volatile fatty acid, food processing wastewater and landfill leachate were used to produce electricity by MFC in the past studies. But there is little knowledge about MFC using wheat bran. We tried to produce electricity by the MFC using wheat bran and succeeded to generate between 0.2V and 0.36V for 250 hour. The factors affecting MFC performance were investigated, we found that substrate concentration, a kind of mediator, ion concentration and electrode material could affect the MFC performance. We tested the discharge transient behavior of the MFC and fitted theoretically calculated values to observed values. By the fitting, we clarified the equivalent circuit constant, i.e., inner resistances and capacitor of the MFC.

Influence of wastewater characteristics on methane potential in food-processing industry wastewaters

In this study, we identified the influence of wastewater characteristics on the theoretical and practical methane potential using different food industrial wastewaters as substrates. Ten composite wastewater samples from five industries were investigated. The ultimate practical methane yields ( B o) were compared to the theoretical methane yields ( B o,th) in order to evaluate the biodegradability of the tested wastewaters and the influence of their physico-chemical characteristics. The analytical method applied to quantify the wastewaters’ organic content proved to influence the estimation of their theoretical yields. The substrate:inoculum ratio as well as the dilution factor of the wastewaters influenced the ultimate practical methane yields differently in each of the wastewaters assessed. Substrate chemical oxygen demand (COD) concentrations did not present any influence on ultimate practical methane yields; on the other hand, it was found that they were affected positively by concentrations of total inorganic carbon when wastewaters were 25% and 50% diluted and affected negatively by concentrations of total acetate when wastewaters were undiluted. Carbohydrate and protein concentrations affected negatively the maximum achieved practical methane yields.