Chemical Oxygen Demand Levels Research Articles

Unlocking the potential of second cheese whey: a comprehensive review on valorisation strategies

AbstractThe second cheese whey (SCW) is the liquid fraction that remains after the production of whey-cheeses. SCW appears as a white to yellow/green opalescent liquid with suspended solids and contains up to 6% lactose and variable amounts of proteins, fats, and mineral salts. Due to its organic load, SCW is characterized by levels of Biochemical Oxygen Demand and Chemical Oxygen Demand that are significantly higher than urban wastewater. Therefore, it poses an environmental challenge and represents a significant cost and a problem for cheese production facilities when it comes to disposal. On the flip side, SCW contains valuable nutrients that make it a cost-effective substrate for bio-based productions including lactose extraction, and the production of lactic acid, bioethanol, eco-friendly bioplastics, biofuels, beverages, bioactive peptides, and microbial starters. A search in Scopus database indicates that despite the numerous potential applications, interest in SCW exploitation is surprisingly limited and, accordingly, sustainable management of SCW disposal remains an unresolved issue. In this review, which marks the first exclusive focus on SCW, with the aim of contributing to increase the interest of both the scientific community and the stakeholders in the exploitation of this by-product, the processes aimed at SCW valorisation will be described, with particular attention to its use in the production of beverages, food and feed, single cell proteins and as a source of biodegradable bioplastics, organic acids and renewable energy. Moreover, to provide valuable insights into its applications and innovations, an overview on patents regarding the exploitation of SCW will be presented. Graphical Abstract

Naturally derived organic biochar as an alternative to commercially activated carbon in the oxygen removal of seafood processing wastewater

AbstractBACKGROUNDThe seafood processing industries are tremendously increasing in numbers which eventually discharge a large quantity of wastewater with a high range of biochemical oxygen demand (BOD) and chemical oxygen demand (COD), directly into the aquatic environment. A high level of BOD and COD in wastewater pertains to a higher level of pollution which must be reduced to prevent hazardous impacts on ecosystems. The main objective of the research aimed to develop cost‐effective biochar and to remove BOD and COD from processing wastewater using two natural biomasses: water hyacinth and sugarcane bagasse.RESULTSNaOH‐treated and non‐treated biochar for both water hyacinth as well as sugarcane bagasse were prepared through the process of pyrolysis carried out at 600 °C with three different residence times of 30, 45 and 60 min. The wastewater was initially analyzed for BOD and COD levels. The results showed that among all the groups of biochars, the water hyacinth NaOH‐treated biochar pyrolyzed at 600 °C for 60 min exhibited significantly (P < 0.05) higher levels of reduction in BOD (86.6 ± 0.03%) and COD (94.3 ± 0.05%) at a residence time of 60 min in D2 (0.5 g (250 mL)−1). The maximum removal efficiency was observed for water hyacinth NaOH‐treated biochar pyrolyzed at 600 °C for 60 min.CONCLUSIONThe removal efficiencies of organic load revealed that the treated biochars exhibited a better reduction of nutrients. The biochar efficiencies when compared with those of activated carbon exhibited a higher removal level. The present research can be used to reduce BOD and COD levels in wastewater treatments. © 2024 Society of Chemical Industry (SCI).

Evaluating the Efficacy of Peroxyacetic Acid in Preventing Salmonella Cross-Contamination on Tomatoes in a Model Flume System

The use of flume tanks for tomato processing has been identified as a potential source of cross-contamination, which could result in foodborne illness. This study’s objective was to assess the efficacy of peroxyacetic acid (PAA) at a concentration of ≤ 80 mg/L in preventing Salmonella enterica cross-contamination under various organic loads in a benchtop model tomato flume tank. The stability of 80 mg/L PAA at different chemical oxygen demand (COD) levels was also tested. Tomatoes were spot inoculated with a five-serovar rifampin-resistant (rif+) Salmonella cocktail (106 or 108 colony forming unit (CFU)/tomato). Inoculated (n=3) and uninoculated (n=9) tomatoes were introduced into the flume system containing 0-80 mg/L PAA and 0 or 300 mg/L COD. After washing for 30, 60, or 120 s, uninoculated tomatoes were sampled and analyzed for cross-contamination. All experiments were conducted in triplicate. Increasing the organic load (measured as COD) affected the stability of PAA in water with significantly faster dissociation when exposed to 300 mg/L COD. The concentration of PAA, inoculum level, COD levels, and time intervals were all significant factors that affected cross-contamination. Cross-contamination occurred at the high inoculum level (108 CFU/tomato) even when 80 mg/L PAA was present in the model flume tank, regardless of the organic load level. When the tomatoes were contaminated at a level of 106 CFU/tomato, concentrations as low as 5 mg/L of PAA were effective in preventing cross-contamination at 0 mg/L COD; however, 100% tomatoes (9/9) were positive when the organic load increased to 300 mg/L COD. When the PAA concentration was increased to 10 mg/L, it effectively prevented cross-contamination in the tank, regardless of the presence of organic load. These results suggest that using PAA at concentrations below the maximum limit remains effective in limiting bacterial cross-contamination and offers a more environment-friendly option for tomato packinghouse operators.

Using ultrasonic washing combined with UV-LEDs as a novel chemical-free method to disinfect fresh ready-to-eat produce

The consumption of ready-to-eat fresh produce raises the issue of food-borne pathogen infections; thus, disinfecting ready-to-eat produce for commercial use, such as in homes and restaurants, is important to ensure food safety. Chemical sanitizers are typically used for disinfection. Ultraviolet-light emitting diodes (UV-LEDs) are a novel non-thermal disinfection technology that consumes less energy and generates less heat than traditional UV lamps, making them more appealing to consumers. In this study, we combined ultrasonic (US) washing method with UV-LEDs (US-UV-LEDs) to develop a technique for disinfecting fresh produce without using chemical sanitizers and compared its efficacy with three common household sanitizers (“84” (sodium hypochlorite) disinfectant, kettle descaler (citric acid), and vinegar (acetic acid)). In addition, we investigated the efficacy of this method in controlling pathogen numbers in the water used to wash (washing water) the produce to prevent cross-contamination between water and produce. Cherry tomatoes and lettuce were selected as produce models and Salmonella Typhimurium and Escherichia coli O157:H7 were used as the bacterial models. The results showed that US-UV-LEDs reduced the numbers of S. Typhimurium and E. coli O157:H7 on produce by 2.1–2.2 log CFU/g, consistent with the results achieved by the three household sanitizers; however, kettle descaler and vinegar had a limited effect (2.6–3.5 log CFU/mL) on residual pathogens in the washing water. Furthermore, we created washing water with low (754 mg/L) and high (1425 mg/L) chemical oxygen demand (COD) levels and determined the disinfection efficacy of “84” disinfectant and US-UV-LEDs. The results showed that US-UV-LEDs reduced the number of S. Typhimurium and E. coli O157:H7 by 2.0–2.1 and 1.8–2.1 log CFU/g under low and high COD levels, respectively, which was similar a result to that of “84” disinfectant. However, the residual pathogen numbers in the washing water were reduced to 1.4–1.9 log CFU/mL after treatment with US-UV-LED under high COD, whereas the pathogens were undetected in the washing water disinfected with “84” disinfectant. These results suggest that US-UV-LEDs have better application potential than acidic household sanitizers, but chlorine sanitizer remains the most effective disinfecting method.

Graphene oxide–carbon nanotube composite membrane for enhanced removal of organic pollutants by forward osmosis

Composite membranes constructed using both graphene oxide and carbon nanotubes (CNTs) were designed to strengthen the forward osmosis (FO) technology for the removal of organic contaminants. The nano-membrane was chemically treated with organic acids, which were citric acid in this case for more efficiency in permeability and pollutant removal. The efficiency of the composite membranes in organic pollutants removal was estimated by checking the levels of COD (chemical oxygen demand), TKN (total nitrogen analysis), and (TOC) organic carbon in the water sample before and after applying the technology. The analysis of the study recommends that the nano-membranes may be appropriately used to reduce organic pollutants significantly, to 98.20% efficiency, in addition to elevating water quality standards. This was caused by the higher degree of selectivity and permeability of the membranes that was consequent to the treatment of the organic acid. In brief, the employment of citric acid in the pre-treatment procedures for the preparation of composite graphene oxide-carbon nanotube membranes for FO technology could take water cleaning technologies a step ahead toward sustainable technology. The application of the composite membrane with graphene oxide and carbon nanotubes is not only efficient in cleaning out organic contaminants but it has a lot of added benefits. These membranes are easily manufactured with a long lifespan which, in turn, makes them cost-effective and environmentally friendly. Also, forward osmosis technology reduces the energy demand compared to other water remediation methods, making it a more sustainable solution. The final point of this article is that the using of composite graphene oxide-carbon nanotube membranes treated with an organic acid, such as citric acid, in FO technology not only assists with the water treatment problem but also elevates sustainablility due to its effectiveness and is environmentally friendly.

Hydrodynamic Cavitation – A Promising Technology for Water Treatment

In today's context, water treatment assumes paramount importance due to the scarcity of potable water and the escalating needs of the global population. Hydrodynamic Cavitation (HC) emerges as a promising application in wastewater treatment, particularly when integrated with Advanced Oxidation Processes (AOPs). The study begins with a critical examination of the literature on combined approaches involving hydrodynamic cavitation, followed by experimental findings. The primary objective was to mitigate the chemical oxygen demand (COD) of the sample through HC in conjunction with hydrogen peroxide and Fenton reagent. Subsequently, each run was executed, and the output value obtained from HC was determined. Throughout the research, samples of river water were procured from the Mula-Mutha River in Pune. HC treatment reduced the COD of river water by approximately 60.83 % at 3 pH. Notably, the highest degradation was observed at 9 pH with the use of Sodium persulphate, with the optimal concentration estimated to be 600 ppm. Moreover, a COD reduction exceeding 89 % with a dosage of 15 mM H2O2. Treatment with Fenton reagent for 60 min demonstrated a remarkable COD decrease of up to 93 %, with an optimal H2O2 to FeSO4 molar ratio of 10:1 and at 3 pH. The Fenton procedure alone or in combination with H2O2 and HC proved to be the most efficient for river water characterized by extremely high COD levels, yielding the greatest reduction during experimental trials. The kinetics of HC degradation conformed to a first-order rate law, with the value of a rate constant (K = 7.21 × 10-4 s−1).

Comparative study of wastewater treatment efficiency: ozone vs. atmospheric oxygen with a manganese dioxide catalyst

Abstract This study aims to validate the wastewater treatment technique and compare the effectiveness of applying an ozone mixture and atmospheric oxygen in the presence of a catalyst (manganese dioxide) with various dosages. A total of 540 replicates were performed, corresponding to different levels of manganese dioxide concentrations during oxygen and ozone delivery (270 repetitions for each of the experiments). The research was carried out using an experimental setup developed by the authors. The maximum efficiency of oxidation processes was observed within 15–30 min after the start of the treatment cycle. The decrease in the level of chemical oxygen demand within the first quarter-hour during ozone treatment was significantly greater compared to atmospheric oxygen treatment (p ≤ 0.05). The method's efficiency increased to 53% for ozone and 41% for oxygen after 30 min of purification (p ≤ 0.05). Lower catalyst consumption was observed when using an ozone mixture. The tested technology can be recommended for wastewater treatment with high hydrocarbon concentrations. The findings of the study indicated the potential application of ozone treatment with a manganese catalyst for treating wastewater with high hydrocarbon content, thereby fostering the development of more effective water purification methods in the industrial sector.

Carbonized balsa wood-based photothermal evaporator for treating inorganic chemical wastewater.

Solar desalination provides a sustainable and eco-friendly solution for purifying wastewater, addressing environmental challenges associated with wastewater treatment. This study focuses on the purification of inorganic contaminants from laboratory chemical wastewater (ICWW) using a spherical solar still (SSS). To enhance the evaporation rate and overcome the impact of heavy metals on absorption efficiency, a carbonized balsa wood (CBW) solar evaporator was employed. Balsa wood pieces, carbonized at 250 °C for 15 min, were arranged in a SSS configuration. The CBW-integrated SSS demonstrated a remarkable freshwater productivity of 2.33 L/m2 for ICWW, surpassing the conventional SSS, which produced only 1.5 L/m2. The presence of heavy metal ions (Na+, Ca+, K+, and Mg2+) in ICWW significantly affected the evaporation rate, and the CBW solar evaporator exhibited an impressive removal efficiency of approximately 99%. Water quality parameters, including pH and chemical oxygen demand (COD), were investigated before and after treatment. The CBW-integrated SSS achieved an outstanding COD removal efficiency of about 99.77%, reducing the COD level from 229.51 to 0.521 mg/L. These results underscore the efficacy of the proposed solar desalination system in purifying ICWW, offering a promising approach to address environmental concerns associated with wastewater treatment.

Effectiveness of Canna indica leaves and stalk biochar in the treatment of textile effluent

Textile effluents often include water polluted with heavy metals, organic and inorganic contaminants, and different colors. It is not practical to remove these pollutants from the water. A variety of methods, including ozone, adsorption, membrane separation, biosorption, biodegradation, electrochemical degradation, and UV radiation, might be used in the water treatment procedure. Biochar made from Canna indica leaves and stems was used to remediate textile industry wastewater, which included color and chemical oxygen demand (COD). By using an absorption technique, the biochar was created by roasting the material at 500 °C, which removed the color and COD from the wastewater. The batches were subjected to many variations in temperature, concentration, and dose of biochar throughout the testing phase. Canna leaves have been shown to be effective in reducing COD at doses between one and 1.5 gm. COD levels were reduced by 83%, and color was reduced by around 94%. On the other hand, while keeping a constant dose, it was shown that canna stalks showed noteworthy effectiveness in lowering COD levels, with a range of 33%–48%. When it comes to eliminating color and COD, the leaves of the canna plant show more specificity than those of other plant species. The Jovanovich isotherm showed a good association with the biochar made from Canna indica leaves, according to the examination of the isotherm computation.

Axenic green microalgae for the treatment of textile effluent and the production of biofuel: a promising sustainable approach

An integrated approach to nutrient recycling utilizing microalgae could provide feasible solutions for both environmental control and energy production. In this study, an axenic microalgae strain, Chlorella sorokiniana ASK25 was evaluated for its potential as a biofuel feedstock and textile wastewater (TWW) treatment. The microalgae isolate was grown on TWW supplemented with different proportions of standard BG-11 medium varying from 0 to 100% (v/v). The results showed that TWW supplemented with 20% (v/v) BG11 medium demonstrated promising results in terms of Chlorella sorokiniana ASK25 biomass (3.80 g L−1), lipid production (1.24 g L−1), nutrients (N/P, > 99%) and pollutant removal (chemical oxygen demand (COD), 99.05%). The COD level dropped by 90% after 4 days of cultivation, from 2,593.33 mg L−1 to 215 mg L−1; however, after day 6, the nitrogen (-NO3−1) and total phosphorus (TP) levels were reduced by more than 95%. The biomass-, total lipid- and carbohydrate- production, after 6 days of cultivation were 3.80 g L−1, 1.24 g L−1, and 1.09 g L−1, respectively, which were 2.15-, 2.95- and 3.30-fold higher than Chlorella sorokiniana ASK25 grown in standard BG-11 medium (control). In addition, as per the theoretical mass balances, 1 tonne biomass of Chlorella sorokiniana ASK25 might yield 294.5 kg of biodiesel and 135.7 kg of bioethanol. Palmitic acid, stearic acid, and oleic acid were the dominant fatty acids found in the Chlorella sorokiniana ASK25 lipid. This study illustrates the potential use of TWW as a microalgae feedstock with reduced nutrient supplementation (20% of TWW). Thus, it can be considered a promising feedstock for economical biofuel production.Graphical abstract

Insights into nitrogen removal from leather wastewater by anaerobic ammonium oxidation process: Performance and microbial structure

This study aimed to assess the suitability of anaerobic ammonium oxidation (anammox) process for leather wastewater treatment using two up-flow anaerobic sludge blanket bioreactors by pumping synthetic and real wastewater (named SR and RR), respectively. Both reactors were operated steadily with an average nitrogen removal efficiency of 94–96 % at chemical oxygen demand (COD) level of 100–200 mg·L−1, which were rapidly deteriorated as the COD level increased to 300 mg·L−1 even if at the same COD to total nitrogen (TN) (COD/TN) ratio. The reactor performances could restore after pumping with synthetic wastewater, and then continued to effectively treat leather wastewater. Furthermore, the relative abundance of Candidatus Kuenenia in reactor RR was increased by 34.8 % compared with the reactor SR on day 120. The results revealed that the anammox process can be used for the leather wastewater treatment, thus broadening the engineering application of anammox-based process in industrial wastewater.

Utilizing Hydrodynamic Cavitation with Variable Orifice Patterns for Textile Wastewater Treatment

The presence of hazardous metals, such as nickel and copper, has been identified in the effluents of the textile industries. Due to such hazardous components, this waste water exhibits a significant chemical oxygen demand (COD). Various methods are used to reduce the COD presence in the effluents. This investigation employs hydrodynamic cavitation, to decrease COD levels potentially. This reduction is achieved by implementing different orifice plate designs, including 3-star pattern, 3-circular hole pattern, 5-star pattern, and 5-circular hole pattern, as part of an innovative strategy. According to current investigations, implementing the 5-circular hole layout significantly reduced of COD by 49.14%. In contrast, using the 5-star design yielded a low drop of 34.15% COD. These experimental findings indicated that the most effective orifice plate for removing COD from textile wastewater was a circular design with 5- holes.

EFFECT OF ACTIVATED CHARCOAL PECAN SHELL (Aleurites moluccanus L. Willd) WITH VARIATIONS IN SULFURIC ACID CONCENTRATION ON DECREASED COD AND BOD LEVELS OF LAUNDRY LIQUID WASTE

Pecan shells are organic waste that can be decomposed but the texture is hard enough that it takes a long time to decompose it naturally. Various efforts to utilize pecan shell waste (Aleurites moluccanus L. Willd), one of which is as a raw material for making activated charcoal. This study aims to find out how the effect of pecan shell activated charcoal (Aleurites moluccanus L. Willd) with variations in the concentration of sulfuric acid against a decrease in Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) levels of laundry liquid waste, as well as the effectiveness of the concentration of sulfuric acid activators. The manufacture of pecan shell activated charcoal (Aleurites moluccanus L. Willd) as an adsorbent is carried out through two stages, namely the authoring stage and the activation stage. BOD testing is carried out by the Winkler titration method while COD is carried out by the closed reflux method. The concentration of sulfuric acid used is 0.5 N; 1.0 N; 1.5 N; 2.0 N; and 2.5 N with a soaking time of 2 hours. The results showed that the sulfuric acid activator that was most effective in reducing laundry liquid waste was at a concentration of 1.5 N with the largest decrease value for BOD, namely 955.56 mg/L (25.44 %) and for COD which was 1648.69 mg/L (18.56 %).

Effectiveness of wastewater treatment plant at the removal of nutrients, pathogenic bacteria, and antibiotic-resistant bacteria in wastewater from hospital source.

This study is aimed at assessing the effectiveness of hospital's wastewater treatment plant (WWTP) in removing nutrients, pathogenic bacteria, and addressing antibiotic resistance using a case study of a tertiary hospital in Ibadan, Nigeria. During the dry and wet seasons in the month of July and December, respectively, samples were collected, and analyzed using standard guidelines to examine significant physicochemical parameters of the WTTP; to evaluate the removal efficiency of biological oxygen demand (BOD) and chemical oxygen demand (COD), and to examine the prevalence of pathogenic and antibiotic-resistant bacteria. The results of this study showed that during the dry season, certain parameters exceeded acceptable limits, including temperature, total suspended solids (TSS), total dissolved solids (TDS), phosphate, and nitrate. Although there were reductions in BOD (1555mg/L to 482mg/L) and COD levels (3160mg/L to 972mg/L), they remained above acceptable limits by World Health Organization. In the wet season, the level of COD (20mg/L) in the effluent was within acceptable limit, while the BOD (160mg/L) was above the acceptable limit. The WWTP effectively removed nutrients and reduced the microbial load, as evident from the absence of fecal coliforms in the effluent in both seasons. In respect to BOD removal efficiency, the level of purification of wastewater by the WWTP was 69% during the dry season, while the removal efficiency of COD was 83.54% which showed the efficiency of the WWTP at the removal of COD. However, antibiotic resistance was still present. The study concludes that while the WWTP effectively addressed nutrients and microbial load, additional measures such as tertiary treatment methods like chlorination and UV radiation are necessary to tackle antibiotic resistance. This is crucial to prevent the release of antibiotic-resistant bacteria into the environment, safeguarding human health, animals, plants, and overall environmental well-being.

Molecular investigation into the transformation of recalcitrant dissolved organic sulfur in refinery sour water during stripping process

Refinery sour water primarily originates from the tops of towers in various units and coker condensate, and cannot be discharged directly to a wastewater treatment plant due to high levels of chemical oxygen demand (COD) and organic sulfur contents. Even after the recovery of H2S from the sour water by the stripping process, the effluent still contains a high concentration of dissolved organic sulfur (DOS), which can have a huge bad influence. While chemical composition of dissolved organic matter (DOM) in refinery wastewater has been extensively studied, the investigation of recalcitrant DOS from sour waters remains unclear. In the present study, chemical composition of sour water DOMs (especially DOS) was investigated using fluorescence spectroscopy (excitation-emission matrix, EEM) and mass spectrometry, including gas chromatography-mass spectrometry (GC-MS) and high-resolution Orbitrap MS. The GC-MS and EEM results showed that volatile and low-aromaticity compounds were effectively removed during the stripping process, while compounds with high hydrophilicity and humification degree were found to be more recalcitrant. The Orbitrap MS results showed that weak-polar oxygenated sulfur compounds were easier to be removed than oxygenated compounds. However, the effluent still contained significant amounts of sulfur-containing compounds with multiple sulfur atoms, particularly in the form of highly unsaturated and aromatic compounds. The Orbitrap MS/MS results of CHOS-containing compounds from the effluent indicate that the sulfur atoms may exist as sulfonates, disulfide bonds, thioethers. Understanding the composition and structure of sour water DOS is crucial for the development of effective treatment processes that can target polysulfide compounds and minimize their impact on the environment.

Eco-friendly green roof from biodegradable substrate for stormwater quality improvement

Currently, there is a significant surge of interest in green roof technology for construction buildings due to its numerous environmental benefits, such as stormwater management, energy efficiency, and enhanced urban biodiversity. However, the issue of potential pollutant release from green roof substrates into runoff water, causing water pollution, needs to be addressed. To tackle this concern, a lab-scale green roof model was assessed, utilizing a biodegradable substrate made from banana peels and eggshell waste (organic fertilizer). Three models were tested: a conventional green roof (control), a green roof with chemical fertilizer, and a green roof with organic fertilizer. Various water quality parameters, including pH, total suspended solids (TSS), nitrogen, phosphorus, and potassium (NPK), and chemical oxygen demand (COD), were evaluated. The results demonstrated the effectiveness of organic fertilizer in reducing TSS and COD levels, where the eco-friendly green roof with biodegradable substrate exhibited an impressive performance, achieving a higher COD removal percentage (78%) compared to the green roof with chemical fertilizer (50%). The utilization of organic fertilizer led to an enhancement in the quality of stormwater runoff, resulting in NPK removal percentages ranging from 17% to 25%. Additionally, the organic fertilizer fostered healthier vegetation growth, leading to a greater number of leaves compared to the chemical fertilizer. These findings highlight the potential of eco-friendly green roofs as a sustainable and effective tool for stormwater management, provided suitable substrate materials are employed.

BIOFUEL PRODUCTION FROM SOLID AND LIQUID FRACTIONS OF HYDROTHERMALLY PRETREATED SUGARCANE BAGASSE IN A CONTINUOUS COMPARTMENTALIZED REACTOR AND POTENTIAL METABOLIC PATHWAYS

Solid and liquid fractions of hydrothermally pretreated sugarcane bagasse (SCB) were simultaneously used as substrate of a novel continuous compartmentalized reactor. The effect of four (56, 42, 28, and 14 h) hydraulic retention time (HRT) and three (0.5, 3.0, and 9.0 g L-1) chemical oxygen demand (COD) levels were evaluated on hydrogen (H2) and organic acids production. Higher H2 production and yield (686 mL and 1.63 mol mol-1 carbohydrate, respectively) were obtained under an HRT of 28 h, probably due to the Clostridium and Thermoanaerobacterium metabolisms, which accounted for almost 60% of the microbial relative abundance. Under lower and higher HRT (14 and 56 h, respectively) lactic acid prevailed without hydrogen production. Other value-added chemicals such as citric, valeric and caproic acids were also obtained according to the HRT. From the functional point of view, enzymes from the glycoside hydrolases group (GHs) potentially performed important roles in the lignocellulosic biomass bioconversion.

Response surface methodology optimization of the effect of pH, contact time, and microbial concentration on chemical oxygen removal potential of vegetable oil industrial effluents.

The vegetable oil refinery industry generates highly polluted effluents during oil production, necessitating proper treatment before discharge to prevent environmental hazards. Treating such wastewater has become a major environmental concern in developing countries. Chemical oxygen demand (COD) is a key parameter in assessing the wastewater's organic pollutant load. High COD levels can lead to reduced dissolved oxygen in water bodies, negatively affecting aquatic life. Various technologies have been employed to treat oily wastewater, but microbial degradation has gained attention due to its potential to remove organic pollutants efficiently. This study aims to optimize the biodegradation treatment process for vegetable oil industrial effluent using response surface methodology (RSM). The wastewater's physicochemical properties were characterized to achieve this, and COD removal was analyzed. Furthermore, RSM was used to investigate the combined effects of pH, contact duration, and microbial concentration on COD removal efficiency. The result showed that the microbial strain used recorded a maximum COD removal of 92%. Furthermore, a quadratic model was developed to predict COD removal based on the experimental variables. From the analysis of variance (ANOVA) analysis, the model was found to be significant at p < 0.0004 and accurately predicted COD removal rates within the experimental region, with an R2 value of 90.99% and adjusted R2 value of 82.89%. Contour plots and statistical analysis revealed the importance of contact duration and microbial concentration on COD removal. PRACTITIONER POINTS: Response surface methodology (RSM) optimization achieved a significant chemical oxygen demand (COD) removal efficiency of 92% in vegetable oil industrial effluents. The study's success in optimizing COD removal using RSM highlights the potential for efficient and environmentally friendly wastewater treatment. Practitioners can benefit from the identified factors (pH, contact time, and microbial concentration) to enhance the operation of treatment systems. The developed predictive model offers a practical tool for plant operators and engineers to tailor wastewater treatment processes. This research underscores the importance of sustainable practices in wastewater treatment, emphasizing the role of microbial degradation in addressing organic pollutant loads.

Exploring Bio Augmentation as a Sustainable Approach for COD Reduction in Palm Oil Refinery

Purpose: This study aimed to investigate the effectiveness of Bioaugmentation Technology in addressing elevated levels of Chemical Oxygen Demand (COD) and reducing sludge volume in the aeration tank of a Palm Oil Refinery located in Kalimantan Island, Indonesia. In addressing these concerns, the study employed Bioaugmentation Technology, specifically tailored for the treatment of palm oil mill effluent in both aerobic and anaerobic ponds, with the aim of expediting the breakdown of organic compounds.&#x0D; Methodology: The research focused on evaluating the impact of this technology on organic degradation and sludge reduction in comparison to conventional treatment methods. Conventional Palm Oil Mill Effluent (POME) treatment systems typically utilize large-volume sequential pond arrangements with extended hydraulic retention times (&gt;90 days), resulting in inefficient organic degradation. Conversely, the Bioaugmentation Technology utilized in this study emerged as a natural, non-toxic, and easily implementable solution to operational challenges faced by these systems.&#x0D; Findings: The technology facilitated the rapid breakdown of organic compounds, leading to a reduction in COD and subsequently, a decrease in sludge volume. Based on the observed positive outcomes, it is recommended to consider Bioaugmentation Technology as a viable and efficient solution for POME wastewater treatment in palm oil refineries.&#x0D; Unique contributor to theory, policy and practice: Its capacity to enhance organic degradation, reduce sludge volume, and improve overall treatment plant efficiency suggests its potential as a valuable complementary technology to existing treatment methods in similar operational conditions.

Recommending Surface Water Quality Monitoring for the Nature Reserve Using Multivariate Statistical Methods

Lung Ngoc Hoang Nature Reserve has a crucial role in conserving and protecting the natural ecosystem and biodiversity in the Mekong Delta, Vietnam, and the local communities also receive great benefits from aquatic resources in this nature reserve. This study was conducted to assess water quality in the Lung Ngoc Hoang Nature Reserve and to provide important information for the monitoring program using multivariate statistical methods. Water samples were collected bimonthly from fifteen locations belonging to five functional zones of the nature reserve (i.e., buffer zone, main canal, administrative and service zone, ecological restoration zone, and strictly protected zone). The physiochemical properties of water samples were measured, including temperature, pH, electrical conductivity (EC), total suspended solids (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), sulfate (SO42-), iron (Fe2+), and aluminum (Al3+). The results showed that the levels of TSS, COD, and Fe2+ exceeded the Vietnamese standard on surface water quality, and the DO level was also far below the standard. Besides, the concentrations of TN, TP, and Al3+ in the nature reserve area showed the risk of eutrophication and negative effects on aquatic organisms. Problems of water quality were observed in the main canal and the administrative and service zones more than in the other zones. Cluster analysis (CA) suggested a reduction in the number of monitoring frequencies and locations to four months (i.e., January, April, July, and September) and twelve locations, respectively. This reduction allows for a decrease in the effort and cost of the monitoring program with adequate information to evaluate water quality. Moreover, principal component analysis (PCA) identified five principal components, which could explain 80.98% of the total variance of the initial dataset. Potential pollution sources were also recognized based on PCA, including the nature properties of sulfate-acid soils, livestock, fertilizer, and domestic activities. The findings of this study can enhance our understanding of water quality in the nature reserve area and the effectiveness of future monitoring programs. Doi: 10.28991/CEJ-SP2023-09-015 Full Text: PDF