Dairy Wastewater Research Articles

Valorization of pretreated biogas digestate with black soldier fly (Hermetia illucens, L; Diptera: Stratiomyidae) larvae

Increasing concerns related to the negative environmental impacts of food waste havemotivated the development of new solutions to complete the waste cycle of organic residues. One particular "waste" product, the solid digestate from anaerobic digestion, has been identified for further bioprocessing. Black soldier fly (BSF, Hermetia illucens) larvae are known for their great potential in the processing of organic waste. In this study, this potential was investigated to further process the digestate waste stream. Digestate is considered a low potential source of nutrients for larvae due to the presence of different fiber fractions. However, the lignocellulosic matter in this residue could be enzymatically hydrolyzed to release residual carbohydrates. For this study, digestate from a full-scale anaerobic digestion plant in Quebec (Canada) which processes a range of feedstocks (fruits, vegetables, garden wastes, sludge derived from dairy processing and wastewater treatment) was sourced. Digestate was treated with Accelerase® DUET enzyme complex to hydrolyze lignocellulosic matter and compared to a standard diet. For each treatment, 600 four-day old larvae were fed daily with 160g (70% relative humidity) of diets for 6 days and harvested 3 days later. Although their growth and total biomass were significantly lower than the standard diet, larvae fed on hydrolyzed digestate were almost two times larger than the larvae fed on crude digestate. Furthermore, the content of organic matter, lipids and minerals in the diets and frass were analyzed. Finally, the feasibility of applying BSF treatment for digestate valorization is discussed. According to this study, enzyme-treated digestate does not allow efficient larval growth compared to the standard diet. The development of a more effective method of pretreatment is required for BSF larvae to become an eco-friendly solution for digestate valorization.

Metagenomic insights into the antibiotic resistomes of typical Chinese dairy farm environments.

Antibiotic resistance genes (ARGs) in the environment pose a threat to human and animal health. Dairy cows are important livestock in China; however, a comprehensive understanding of antibiotic resistance in their production environment has not been well clarified. In this study, we used metagenomic methods to analyze the resistomes, microbiomes, and potential ARG bacterial hosts in typical dairy farm environments (including feces, wastewater, and soil). The ARGs resistant to tetracyclines, MLS, β-lactams, aminoglycoside, and multidrug was dominant in the dairy farm ecosystem. The abundance and diversity of total ARGs in dairy feces and wastewater were significantly higher than in soil (P < 0.05). The same environmental samples from different dairy have similar resistomes and microbiomes. A high detection rate of tet(X) in wastewater and feces (100% and 71.4%, respectively), high abundance (range from 5.74 to 68.99 copies/Gb), and the finding of tet(X5) challenged the clinical application of the last antibiotics resort of tigecycline. Network analysis identified Bacteroides as the dominant genus in feces and wastewater, which harbored the greatest abundance of their respective total ARG coverage and shared ARGs. These results improved our understanding of ARG profiles and their bacterial hosts in dairy farm environments and provided a basis for further surveillance.

Ca(ClO)2 pretreatment enhancing suspended solids removal through flocculation from digested dairy wastewater and its mechanisms

Intensive animal farming produces large volume of digested liquid, and overdose application often causes the pollution of surface water and groundwater. Therefore, post-treatment is very necessary for the discharging of surplus digested liquid, but the removal of high concentrations of suspended solids (SS) in the digested liquid is a challenge. In this study, the effect of Ca(ClO)2 pretreatment on SS flocculation removal of digested dairy wastewater was investigated. The results showed that, without Ca(ClO)2 pretreatment, the flocculation by polyacrylamide (PAM), polyferric sulfate (PFS) or polymeric aluminum chloride (PAC) only removed 42.6 %–50.4 % SS from anaerobic digested liquid. With the combination of Ca(ClO)2 pretreatment and PAC flocculation together, the SS removal efficiency can reach 80 %. The total chemical oxygen demand (TCOD) removal had a similar trend with SS removal, but soluble chemical oxygen demand (SCOD) removal was less affected by the pretreatment and flocculation. More than 75 % of orthophosphate (SRP) and total soluble phosphorus (TSP) was removed after Ca(ClO)2 pretreatment and flocculation with PFS or PAC. Ca(ClO)2 pretreatment also effectively inactivated fecal bacteria. The mechanisms of Ca(ClO)2 pretreatment enhancing SS flocculation removal were further elucidated. The SS removal was the action of ClO− and Ca2+ together. The function of ClO− was to break down suspended particles, change the surface, and decrease the absolute Zeta potential, while the function of Ca2+ was to form precipitation. This result indicates that Ca(ClO)2 pretreatment can effectively enhance the SS flocculation removal of anaerobic digested liquid.

The Cultivation of Biohydrogen-Producing Tetraselmis subcordiformis Microalgae as the Third Stage of Dairy Wastewater Aerobic Treatment System

The development of wastewater treatment systems, including competitive methods for nitrogen and phosphorus removal, is focused on intensifying final technological effects with due care taken for economic and environmental concerns. Given the possibility of integrating wastewater treatment processes with biofuel production, the prospective seems to be technologies harnessing microalgal biomass. The present study aimed to verify the feasibility of applying T. subcordiformis genus microalgae as the third stage of the dairy wastewater treatment process and to determine microalgae biomass production effectiveness and hydrogen yield in the biophotolysis process. The study proved that microalgae cultivation with dairy wastewater was nearly 35% less effective compared to that with a chemically pure medium. Nitrogen and phosphorus compounds contaminating wastewater were found to represent an available source of nutrients for T. subcordiformis population. The volume of hydrogen produced ranged from 116 ± 7 cm3 to 162 ± 7 cm3, and the percentage of H2 content in the biogas ranged from 55.4 ± 2.2% to 57.2 ± 4.1%. A significantly higher hydrogen yield per initial biomass concentration, reaching 69 ± 4.2 cm3/go.d.m., was determined in the variant with wastewater accounting for 50% of the culture medium. The respective value noted in the control respirometer was 54 ± 2.1 cm3/go.d.m.

Comparative appraisal of nutrient recovery, bio-crude, and bio-hydrogen production using Coelestrella sp. in a closed-loop biorefinery.

A closed loop algal-biorefinery was designed based on a three-stage integration of dairy wastewater (DWW) treatment, hydrothermal liquefaction (HTL) of defatted algal biomass, and acidogenic process in a semi-synthetic framework. Initially, Coelestrella sp SVMIICT5 was grown in a 5L photo-bioreactor and scaled up to a 50L flat-panel photo-bioreactor using DWW. The microalgal growth showed higher photosynthetic efficiency, resulting in a biomass growth of 3.2g/L of DCW with 87% treatment efficiency. The biomolecular composition showed 26% lipids with a good fatty acid profile (C12-C21) as well as carbohydrate (24.9%) and protein (31.8%) content. In the second stage, the de-oiled algal biomass was valorized via HTL at various temperatures (150°C, 200°, and 250°C) and reaction atmospheres (N2 and H2). Among these, the 250°C (H2) condition showed a 52% bio-crude fraction and an HHV of ∼29.47MJ/kg (bio-oil) with a saturated hydrocarbon content of 64.3% that could be further upgraded to jet fuels. The energy recovery (73.01%) and elemental enrichment (carbon; 65.67%) were relatively greater in H2 compared to N2 conditions. Finally, dark fermentation of the complex-structured HTL-AF stream resulted in a total bio-H2 production of 231ml/g of TOC with a 63% treatment efficiency. Life cycle analysis (LCA) was also performed for the mid-point and damage categories to assess the sustainability of the integrated process. Thus, the results of this study demonstrated comprehensive wastewater treatment and valorization of de-oiled algal biomass for chemical/fuel intermediates in the biorefinery context by low-carbon processes.

Combination of chemical coagulation and membrane-based separation for dairy wastewater treatment.

An important factor resulted from the ascension of the milk and milk-based by-products production is many effluents directly released into the environment. The main objective of this study was to evaluate the efficiency of the combination of the chemical coagulation, with ferric chloride as a coagulant, and the membrane separation processes (MSP) and reverse osmosis (RO) processes in the treatment of effluents from a powdered milk dairy industry. To evaluate the effectiveness of the integration of these mechanisms, the characterization of the effluents was carried out through Total Nitrogen (Ntotal), Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), color, pH, and turbidity analysis. Regarding the treatments with ferric chloride, the Ntotal removal was up to 55.7% (concentration of 1.2g L- 1) and the color up to 50% (0.7g L- 1). For the MSP and RO treatments, the color removal was up to 100% (1st RO), turbidity up to 100% (1st RO), COD up to 98.7% (3rd RO), and TOC up to 96.7% (3rd RO). Finally, the integration of the chemical coagulation and MSP processes was efficient for the treatment of dairy industry wastewater and provides the return of water in appropriate characteristics according to legislation.

Effect of nutrients, inoculum and co-substrates on methane potential of cattle manure

In this research, the methane potential of the codigestion of cattle manure (CM) with guinea pig manure (GPM) and dairy wastewater (DW) was evaluated. The effect of the addition of nutrients, inoculum (I) and co-substrates on methane production was studied. Later, two low-cost tubular biodigesters were implemented, at a rural farm in the cold climate municipality of Cumbal, fed with the mixture of CM and co-substrates that produced higher biogas production at the lab scale. The results evidenced that the addition of nutrients had no significant effect on methane potential. The mixture CM + GPM + DW + I, produced a theoretical biomethane potential (BMP) of 69.07%, significantly higher than the percentage of the theoretical BMP obtained individually, 43.81% and 34.49% for CM + I and DW+ I respectively. Further, it was observed that the addition of inoculum avoided problems of acidification. Finally, it was proved that this process can reduce environmental contamination and, at the same time, be a sustainable source of renewable energy for rural families in Cumbal (Nariño-Colombia).

THE ROLE OF SODIUM ION IN PHOSPHORUS REMOVAL WHEN ALUM IS USED AS A COAGULANT

Jar examination was applied to treat dairy water by using alum as a coagulant. Synthetic samples similar to actual wastewater were prepared from real dairy products to achieve the work. All tests of characteristics have been performed according to American Public Health Association (APHA), American Water Works Association (AWWA), and Water Environment Federation (WEF). The apparatus used in this study is the Jar test model JLT 6 Leaching test VELP Scientifica, with all kits and tools that could complete the work. The results showed the ability of aluminum sulfate to remove phosphorous from dairy wastewater by up to 95%. This resulted in an optimum aluminum dose equal to 0.5 mg / l at 20°C, and a gradient speed of 1076.915 seconds. -1. These results correspond to the role of the sodium ion in removing contaminants as a catalyst; the sodium ion concentration that contributed to this activity was 60 mg per liter, representing 23.07% of the initial concentration. The main goal of this article, it’s how can exploit the factors and circumstances adjacent to reducing pollutants without increasing aluminum dosages.

Investigation of lactic acid production in optimized dairy wastewater culture medium

Investigation of lactic acid production in optimized dairy wastewater culture medium

Performance evaluation of vertical constructed wetland units with hydraulic retention time as a variable operating factor

The current research intends to assess the impact of shorter hydraulic retention time (HRTs) and different sized filter material on the pollutant removal performance of two pilot-scale vertical sub-surface flow constructed wetlands (VSSF CW) to treat dairy wastewater. Two CWs (CW-1 & CW-2) were filled with 10 and 20 mm gravels, respectively, planted with Arundo donax, and operated at three different HRTs for treating dairy farm wastewater viz. 6, 12, and 24 h. Over three months, the effluent was tested for TSS, BOD5, TP, and NH4–N removal using standard procedures at regular intervals. Average concentrations of TSS, BOD5, TP, and NH4–N at the final outlets CW-1 and CW-2 were recorded in the range of; TSS: 44.7–118.7 mg L−1, BOD5: 8.1–33.9 mg L−1, TP: 13.7–22.2 mg L−1and NH4–N: 9.1–11.4 mg L−1, respectively. The highest removal of TSS (81.2%), BOD5 (90.2%), TP (65.1%), and NH4–N (82.5%) from wastewater was seen after a 12 h HRT, whereas maximum DO rise (579.0%) was reported after a 6 h HRT in 20 mm gravel-filled CW units. Short HRTs of 6, 12, and 24 h were found to be effective in removing all pollutants from wastewater and maintaining a constant treatment throughout the evaluation period. Results suggest that VSSF CW systems can be operated efficiently under short HRTs while still effectively removing contaminants from dairy wastewater.

Alkali pretreatment method of dairy wastewater based grown Arthrospira platensis for enzymatic degradation and bioethanol production

Owing to increasing gasoline demand and fossil fuel depletion. Biofuel is increasingly being produced using an alternative source, such as algae. Microalgae is one such promising biofuel-generating solution. This investigation used the Response Surface Methodology (RSM), focusing on Central Composite Design to improve the chemical pretreatment conditions for the microalgae (Arthrospira platensis). The significant influence of sodium hydroxide (NaOH) concentration and pretreated time on sugar yield and pretreatment processes wereoptimized using CCD. Pretreatment parameters such as duration (1 to 3 days) and NaOH concentrations (1 to 3 % (w/v)) accumulated in the pretreatment model. Following the pretreatment stages, the microalgae biomass was digested with a cellulase enzyme and Trichoderma sp. under three conditions cellulase enzyme 2 %, Trichoderma sp. 2 %, and cellulase enzyme 1 % combined with Trichoderma sp. 1 %. The combinations were incubated at 30 °C for 1, 2, and 3 days, transferring to fermentable sugar for Saccharomyces cerevisiae TISTR5020 to use in bioethanol fermentation.

Modeling and prediction of COD and turbidity removals from dairy wastewaters by Fenton process using RSM and ANN

Modeling and prediction of COD and turbidity removals from dairy wastewaters by Fenton process using RSM and ANN

A meta-analysis of LCAs for environmental assessment of a conceptual system: Phosphorus recovery from dairy wastewater

A significant increase in phosphorus-rich dairy wastewater coincides with a decrease in the availability of fossil phosphate rock resources in Europe. This confluence of events has led to the development of technologies for phosphorus recovery from dairy wastewater. This study aims to inform and guide such development with regard to life cycle environmental impacts prior to their implementation in dairy contexts. With the lack of inventory data at this point and the non-existence of earlier life cycle assessments on the use of phosphorus recovery technologies in a dairy context in literature, we performed a meta-analysis where we extracted and compared published results on life cycle environmental impacts from two fields (1) dairy industries, with a focus on the dairy wastewater treatment and (2) phosphorus recovery technologies in a municipal wastewater treatment context. The results show that despite its intended effect, normal dairy wastewater treatment in many cases still contributes significantly to eutrophication. Most of the phosphorus recovery technologies examined here exhibited a lower global warming potential and cumulative energy demand than those of dairy wastewater treatment processes. It indicates that problem shifting could be avoided when phosphorus recovery is introduced. However, no technologies involving incineration have had the impact of acidification reported which represents a potential knowledge gap since impacts are expected related to incineration emissions. A comparison between the extracted data for phosphorus recovery technologies shows that there are lower impacts related to technologies that recover phosphorus from the liquid phase, than from sludge or ash.

Biogenic Silver and Magnetic Nanoparticles Using Bacillus subtilis B2 Bioflocculants; Production, Properties and Antibacterial Potential in Dairy Wastewater Treatment

Biogenic Silver and Magnetic Nanoparticles Using Bacillus subtilis B2 Bioflocculants; Production, Properties and Antibacterial Potential in Dairy Wastewater Treatment

TiO2 Nanoparticles as Bifunctional Adsorbent/Photocatalyst for Degradation of Effluent from Local Dairy in Telangana

Contamination of precious life sources with industrial waste including dairy effluent is an increasing concern worldwide. Over the past few years, titanium dioxide nanoparticles have drawn worldwide attention as an efficient photocatalyst and adsorbent for wastewater treatment. The current study refers to the potential of nitrogen doped titanium dioxide nanoparticles as an adsorbent and photocatalyst to purify wastewater from the local dairy to meet the quality of wastewater discharged into public sewers. The Nitrogen doped titanium dioxide (TiO2) Nano Materials were prepared by sol-gel technique and calcined at various temperatures. Characterization techniques such as SEM, XRD and FTIR were performed and Zeta potential was estimated. Efficiency of degradation as applied to dairy effluent has been examined varying the parameters such as time of exposure and dose of nanoparticles along with solution pH variation monitored during study. A good reduction in COD of about 99 % was observed after treatment under visible light. It is observed that calcining temperature affects activity of TiO2 nano particles. Furthermore, statistical analysis that represent experimental response as a function of independent parameters as well as analyse the interaction between the parameters was successfully employed. The results showed that TiO2 nanoparticles can be employed as adsorbents for the treatment of dairy waste water. Keywords: Adsorbent, Chemical oxygen demand, Dairy effluent, Doping, nanoparticles, TiO2

A novel hybrid coagulation-intermittent sand filter for the treatment of dairy wastewater

An intermittent sand filter (ISF) is a simple and cost-effective treatment method that may be adopted on farms to treat dairy wastewater (DWW). However, the use of ISFs has been limited due to the large area required for treatment, and the risk of filter clogging and phosphorus (P) breakthrough, which decrease the operational lifetime. To overcome these limitations, this study uses a novel, pilot-scale coagulation-sedimentation process prior to loading ISFs with DWW. The performance and operational lifetime of this new hybrid coagulation-ISF system was compared to a conventional ISF system in a replicated outdoor pilot-scale experiment over a 43-wk study duration (covering an entire milking season on a farm in Ireland). The hybrid system was able to operate effectively at a higher hydraulic loading rate than a conventional ISF system. The effluent quality from the conventional ISF deteriorated over the timeframe of the study until clogging occurred, while the hybrid system continued to perform effectively without any evidence of clogging or P breakthrough. The hybrid system obtained removal efficiencies ≥99% for all measured water quality parameters (chemical oxygen demand, total suspended solids, total P, ammonium and turbidity), and complied with EU directives concerning urban wastewater treatment. Overall, the hybrid coagulation-ISF is a promising technology that requires a small area (75% reduction in footprint in comparison to a conventional ISF) and minimal operator input, and produces high effluent quality.

Treatment of different dairy wastewater with Chlorella sorokiniana: removal of pollutants and biomass characterization

AbstractBACKGROUNDThere is a continuous need for the development of novel processes for the sustainable management of dairy wastewater. The use of microalgae for wastewater decontamination and production of valuable biomass seems a promising alternative; however, limited information currently exists on the chemical characteristics of the biomass cultivated in effluents from the dairy industry. In this paper, experiments were carried out with the microalga Chlorella sorokiniana and different types of dairy effluents (raw dairy wastewater, anaerobically treated dairy wastewater, cheese whey). The collected biomass was characterized for the existence of proteins, starch, lipids, lutein, β‐carotene, polyphenolic compounds and amino acids.RESULTSThe removal of chemical oxygen demand and NH4‐N was higher than 91% and 80%, respectively, for all types of dairy effluents, while the removal of total phosphorus ranged between 20% and 84%. The protein, starch and lipid contents of the microalgal biomass ranged between 28.6% and 52.8%, 10.5% and 13.3%, and 36.8% and 40.2%, respectively. The concentration of lutein increased after treatment, reaching values up to 508 mg kg−1, whereas amino acid concentrations were decreased due to nitrogen inefficiency. The biomass cultivated in anaerobically treated dairy wastewater was characterized by the higher total phenolic content; tyrosol concentration reached 20.2 mg kg−1.CONCLUSIONChlorella sorokiniana can efficiently remove the major pollutants from effluents of dairy industry, while the produced biomass is a source of proteins, carbohydrates and lipids. Additionally, it contains important amounts of pigments, phenolic compounds and amino acids. Further research is required for the conditions that achieve optimal biochemical characteristics of the produced biomass. © 2022 Society of Chemical Industry (SCI).

Simultaneous saccharification and citric acid production from paper wastewater pretreated banana pseudostem: Optimization of fermentation medium formulation and kinetic assessment

This study optimized the simultaneous saccharification and citric acid (CA) production from banana pseudostem (BP). Thereafter, kinetic assessment of Aspergillus brasiliensis growth and CA production were determined for the optimum conditions using fresh water (SSFoptimizedFW) or dairy wastewater (SSFDWW) and compared to Sabouraud Dextrose Emmon’s medium modified with BP (SSFSDEmodified). The optimized conditions gave a CA concentration of 14.408 g/L. Kinetic assessment revealed the same maximum specific growth rates (μmax) (0.05 h−1) for all three bioprocesses, while the SSFSDEmodified process resulted in the highest maximum potential CA concentration (Pm) (13.991 g/L) in comparison to the SSFDWW (Pm = 13.095 g/L) and SSFoptimizedFW (Pm = 12.967 g/L) systems. Findings from this study facilitates the implementation of waste-based lignocellulosic bioprocesses that may eradicate the use of expensive pretreatment chemicals, fermentation medium constituents, and resources, in keeping with the water, energy and food nexus towards developing a circular bioeconomy.

A novel hybrid coagulation-constructed wetland system for the treatment of dairy wastewater

Constructed wetlands (CWs) are a cost-effective and sustainable treatment technology that may be used on farms to treat dairy wastewater (DWW). However, CWs require a large area for optimal treatment and have poor long-term phosphorus removal. To overcome these limitations, this study uses a novel, pilot-scale coagulation-sedimentation process prior to loading CWs with DWW. This hybrid system, which was operated on an Irish farm over an entire milking season, performed well at higher hydraulic loading rates than conventional CWs, and obtained removal efficiencies ≥99 % for all measured water quality parameters (chemical oxygen demand, total nitrogen and phosphorus, total suspended solids and turbidity), which complied with EU directives concerning urban wastewater treatment. Overall, the hybrid coagulation-CW is a promising technology that requires a smaller area than conventional CWs and minimal operator input, and produces high effluent quality.

Energy and nutrient recovery from dairy and municipal wastewater sources in a terracotta-biochar bioelectrochemical system

Energy and nutrient recovery from dairy and municipal wastewater sources in a terracotta-biochar bioelectrochemical system