Process analysis and optimization of single stage flexible fibre biofilm reactor treating milk processing industrial wastewater using response surface methodology (RSM)

Investigation and characterization of changes in potato peels by thermochemical acidic pre-treatment for extraction of various compounds

Potato peel waste (PPW) is an underutilized substrate which is produced in huge amounts by food processing industries. Using PPW a feedstock for production of useful compounds can overcome the problem of waste management as well as cost-effective. In present study, potential of PPW was investigated using chemical and thermochemical treatment processes. Three independent variables i.e., PPW concentration, dilute sulphuric acid concentration and liberation time were selected to optimize the production of fermentable sugars (TS and RS) and phenolic compounds (TP). These three process variables were selected in the range of 5-15 g w/v substrate, 0.8-1.2 v/v acid conc. and 4-6 h. Whole treatment process was optimized by using box-behnken design (BBD) of response surface methodology (RSM). Highest yield of total and reducing sugars and total phenolic compounds obtained after chemical treatment was 188.00, 144.42 and 43.68 mg/gds, respectively. The maximum yield of fermentable sugars attained by acid plus steam treatment were 720.00 and 660.62 mg/gds of TS and RS, respectively w.r.t 5% substrate conc. in 0.8% acid with residence time of 6 h. Results recorded that acid assisted autoclaved treatment could be an effective process for PPW deconstruction. Characterization of substrate before and after treatment was checked by SEM and FTIR. Spectras and micrographs confirmed the topographical variations in treated substrate. The present study was aimed to utilize biowaste and to determine cost-effective conditions for degradation of PWW into value added compounds.

Multicore-shell MnO2@Ppy@N-doped porous carbon nanofiber ternary composites as electrode materials for high-performance supercapacitors

In this study, a multicore-shell ternary composite electrode material (MnO₂@Ppy@NPCNFs) with excellent electrochemical performances was prepared by using surface modification, in which core-shell Ppy@N-doped porous carbon nanofibers (Ppy@NPCNFs) with large specific surface area and high conductivity were used as the substrate (a multicore layer), and MnO₂ was loaded on the substrate by hydrothermal synthesis to form a shell layer, further improving the SC of electrode material. The parameters of hydrothermal growth of MnO₂ on Ppy@NPCNFs were explored by means of the control variable method and response surface methodology, and the optimal parameters were predicted and verified. Electrochemical test results showed that the SC of MnO₂@Ppy@NPCNFs prepared under the optimal reaction parameters was as high as 595.77 F g^-1, and its capacitance retention was 96.2 % after 1000 cycles. Moreover, a symmetric supercapacitor prepared with the optimal multicore-shell electrode showed an energy density of 9.36 Wh kg^-1 at a power density of 1000 W kg^-1 and a retention rate of 92.46 % after 1000 cycles, indicating the promising application of multicore-shell ternary composite electrode material in high-performance supercapacitors.

Treatment capacity of a novel flexible fibre biofilm bioreactor treating high-strength milk processing wastewater

This study was focused on the capacity investigation of a novel multistage flexible fibre biofilm reactor (MS-FFBR) to treat milk processing wastewater (MPW) with high organic loading (OLR). The MS-FFBR performance was evaluated at four intermediate stages separately, and also the final effluent quality of the overall system with an influent chemical oxygen demand (COD_in) ranged from 1500 ± 20 to 6000 ± 50 mg/L and hydraulic retention times (HRTs) of 8, 12, and 16 h. By comparting the bioreactors into the four stages effectively enhanced the bioreactor's performance. The maximum TCOD removal efficiency was achieved at the first stage, which was about 89 ± 20, 82 ± 20, and 78 ± 20% at HRTs of 16, 12, 8 h, and low COD_in of 1600 ± 20, 1590 ± 20, and 1673 ± 20 mg/L, respectively. However, the first stage had less contribution to TCOD removal at high COD_in concentrations, reported to be about 42 ± 4%, 46 ± 4%, and 25 ± 4% at COD_in of 5960 ± 40, 5830 ± 40, and 5870 ± 40 mg/L, respectively. Furthermore, the MS-FFBR was effective in removing total suspended solids (TSS) and turbidity. The bioreactor has reduced the effluent turbidity to 9.0 ± 0.2, 20.0 ± 0.6, and 16.1 ± 0.5 NTU at low COD_in concentrations of 1600 ± 20, 1590 ± 20, and 1670 ± 20 mg/L and HRTs of 16, 12, and 8 h, respectively. The bioreactor revealed a high COD removal rate increased from 2.3 ± 0.1 to 12.2 ± 0.4 kg TCOD/m³d by increasing the OLR from 2.4 ± 0.1 to 17.6 ± 0.4 kg TCOD/m³d, confirming high reactor capacity for treatment of high-strength wastewater. Kinetic studies confirmed that the biomass yield was low at various HRTs ranging from 0.1 to 0.2 gVSS/gCOD.

Effect of Different Operational Conditions on the Treatment Performance of Milk Processing Wastewater (MPW) Using a Single Stage Flexible Fibre Biofilm Reactor (SS-FFBR)

The performance of a biofilm system, single-stage flexible fibre biofilm reactor (SS-FFBR) treating milk processing wastewater (MPW) is evaluated under various process and operational conditions. The system behavior is analyzed with different biological and physical parameters. Results show that the high COD removal efficiency of 95% is obtained at a low COD_in concentration of 809 mg/L. However, the COD removal is slightly decreased to 91.7% once the COD_in concentration incremented to nearly 4000 mg/L. The effect of organic loading rate (OLR) on the SS-FFBR performance is examined as total suspended solids removal efficiency, dissolved oxygen, and turbidity. The SS-FFBR showed considerable performance, so that 89.9% and 89.7% removal efficiencies in terms of COD and TSS removals, respectively, obtained at the highest OLR of 11.7 kg COD/m³d. TSS removal efficiency of 96.7% is obtained at a low OLR of 1.145 kg COD/m³d. A linear relationship between the OLR and COD removal rate was revealed. The COD removal rate was incremented from 1.08 to 10.68 kg COD/m³d as the OLR increased from 1.145 to 11.7 kg COD/m³d. Finally, the operating system is a promising technique recommended to treat various industrial wastewaters with high OLR.

Advancements of sequencing batch biofilm reactor for slaughterhouse wastewater assisted with response surface methodology

Slaughterhouse wastewater (SWW) contains a significant volume of highly polluted organic wastes. These include blood, fat, soluble proteins, colloidal particles, suspended materials, meat particles, and intestinal undigested food that consists of higher concentrations of organics such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrogen and phosphorus hence an efficient treatment is required before discharging into the water bodies. The effluent concentrations and performance of simultaneous sequential batch biofilm reactor (SBBR) with recycled plastic carrier media support are better than the local single-stage sequential batch reactor (SBR), which is lacking in the literature in terms of COD, NH₃, NO₃, and PO₄ treatment efficiency. The present study reports a novel strategy to remove the above mentioned contaminants using an intermittently aerated SBBR with recycled plastic carrier media support along with simultaneous nitrification and denitrification. The central composite design was evaluated to optimize the treatment performance of seven different process variables including; different alternating conditions (Oxic/anoxic) for aeration cycles (3/2 h in a 6 h cycle, 6/5 h in a 12 h cycle and 9/8 h in an 18 h cycle) and hydraulic retention time (6, 12 and 18 h). The average removal efficiencies are 94.5% for NH₃, 93% for NO₃ and 90.1% for PO₄, and 99% for COD. The study reveals that the denitrification in the post-anoxic phase was more efficient than the pre-anoxic phase for pollutant removal and maintaining higher quality effluent. The effluent concentrations and performance of simultaneous SBBR with recycled polyethylene carrier support media were better than local SBR system in terms of COD, NH₃, NO₃ and PO₄ treatment efficiency. Results stipulated the suitability of SBBR for wastewater treatment and reusability as a sustainable approach for wastewater management under optimum conditions.

Simultaneous Removal of Organic Matter and Nutrients from High Strength Organic Wastewater Using Sequencing Batch Reactor (SBR)

Industrial wastewater discharges often contain high levels of organic matter and nutrients, which can lead to eutrophication and constitute a serious hazard to receiving waters and aquatic life. The purpose of this study was to examine the efficacy of using a sequencing batch reactor (SBR) to treat high-strength organic wastewater for the removal of both chemical oxygen demand (COD) and nutrients (nitrogen and phosphorus). At a constant COD concentration of approximately 1000 mg/L, the effects of cycle time (3 and 9 h) and various C:N:P ratios (100:5:2, 100:5:1, 100:10:1, and 100:10:2) were investigated using four identical SBRs (R1, R2, R3, and R4). According to experimental data, a significant high removal, i.e., 90%, 98.5%, and 84.8%, was observed for COD, NH3-N, and PO43−-P, respectively, when C:N:P was 100:5:1, at a cycle time of 3 h. Additionally, when cycle time was increased to 9 h, the highest levels of COD removal (95.7%), NH3-N removal (99.6%), and PO43−-P removal (90.31%) were accomplished. Also, in order to comprehend the primary impacts and interactions among the various process variables, the data was statistically examined using analysis of variance (ANOVA) at a 95% confidence level, which revealed that the interaction of cycle time and C/N ratio, cycle time and C/P ratio is significant for COD and NH3-N removal. However, the same interaction was found to be insignificant for PO43−-P removal. Sludge volume index (SVI30 and SVI10) and sludge settleability were studied, and the best settling was found in R3 with SVI30 of 55 mL/g after 9 h. Further evidence that flocs were present in reactors came from an average ratio of SVI 30/SVI 10 = 0.70 after 9 h and 0.60 after 3 h.

Enhanced removal of fluoride, nitrate, and calcium using self-assembled fungus-flexible fiber composite microspheres combined with microbially induced calcium precipitation

Self-assembled fungus-flexible fiber composite microspheres (SFFMs) were firstly combined with microbially induced calcium precipitation (MICP) in a continuous-flow bioreactor and achieved the efficient removal of fluoride (F^-), nitrate (NO₃^-), and calcium (Ca²⁺). Under the influent F^- of 3.0 mg L^-1, pH of 7.0, and HRT of 8 h, the average removal efficiencies reached 77.54%, 99.39%, and 67.25% (0.29, 2.03, and 8.34 mg L^-1 h^-1), respectively. Fluorescence spectrum and flow cytometry analyses indicated that F^- content significantly affected the metabolism and viability of bacteria. SEM images showed that flexible fibers and intertwined hyphae provided effective locations for bacterial colonization in SFFMs. The precipitated products were characterized by XRD and FTIR, which revealed that F^- was mainly removed in the form of calcium fluoride and calcium fluorophosphate (CaF₂ and Ca₅(PO₄)₃F). High-throughput analysis at different levels demonstrated that Pseudomonas sp. WZ39 acted as the core strain, which played a crucial role in the bioreactor. The mechanism of enhanced denitrification was attributed to minor F^- stress and bioaugmentation technology. This study highlighted the superiorities of SFFMs and MICP combined remediation and documented a promising option for F^-, NO₃^-, and Ca²⁺ removal.

Engineering management of starter cultures in study of temperature of fermentation of sour-milk drink with apiproducts

The article considers the solution of problematic issues of engineering management of poly fermentation in the study of fermentation temperature of sour-milk drink with apiproducts. In the development of fermented dairy products, the components that are part of them, changes in their composition, and properties in the interconnection are considered as a technological system. The authors took into account that food technologies based on the use of the pure culture of one microorganism are limited by the capabilities of its fermentation system systems, the ultimate goal may not be achieved even by changing the conditions and parameters of cultivation. To successfully carry out fermentation processes in the technological system, a combination of cultures, associations of microorganisms with a wide range of fermentation products in contrast to one culture is promising to use. All experimental samples on a set of indicators prevailed control ones. The leader was a sample fermented with yeast with an equal ratio of cultures at a temperature of 38 – 40 °C. The authors found that the set of indicators of finished products for the production of sour-milk drinks with a complex of apiproducts, it is necessary to choose a three-strain poly fermentation product with a congruent ratio of cultures and set optimal fermentation regimes 39 ±1ºC for 5.0 ±0.3 hours.

Adsorption of phenol and bisphenol A on river sediments: Effects of particle size, humic acid, pH and temperature

Phenolic Endocrine Disrupting Chemicals (EDCs) have drawn more and more interest due to their prevalence and persistence in aquatic environment. To study the adsorption of various phenolic EDCs on river sediments under natural conditions, we first sought to analyze the distribution characteristics of phenol and bisphenol A (BPA) in sediment from the Bahe River. The static adsorption experiments contained either single- or dual-contaminant of phenol and/or BPA in the system; they were conducted to characterize the adsorption of these two pollutants in the surface sediments and the main factors affecting the adsorption processes of the dual-contaminant system, including particle size, humic acid (HA) concentration, pH, and temperature. Results showed that in certain seasons, there was a significant correlation between the levels of phenol and BPA in Bahe sediments. When comparing the adsorption behaviors of phenol and BPA on sediments in single- and dual-contaminant systems, we found that the phenol adsorption behavior varied, while that of BPA remained consistent across the different systems. Moreover, different effects were observed with regards to a single factor and the interaction of multiple factors on the adsorption of pollutants. Of the four single factors, only HA concentration had a significant effect on the phenol adsorption in sediment. When considering the interaction of multiple factors, the interaction between HA concentration and temperature significantly promoted the adsorption of phenol. The influence of factors on the adsorption of BPA was in the following order: particle size > HA concentration > pH > temperature. Particle size significantly inhibited BPA adsorption in the sediment, while the interaction between particle size and pH increased BPA adsorption.

The Influence of Pluronic F-127 Modification on Nano Zero-Valent Iron (NZVI): Sedimentation and Reactivity with 2,4-Dichlorophenol in Water Using Response Surface Methodology

Nano zero-valent iron (NZVI) is widely used for reducing chlorinated organic pollutants in water. However, the stability of the particles will affect the removal rate of the contaminant. In order to enhance the stability of nano zero-valent iron (NZVI), the particles were modified with F-127 as an environmentally friendly organic stabilizer. The study investigated the effect of the F-127 mass ratio on the colloidal stability of NZVI. Results show that the sedimentation behavior of F-NZVI varied at different mass ratios. A biphasic model was used to describe the two time-dependent settling processes (rapid sedimentation followed by slower settling), and the settling rates were calculated. The surface morphology of the synthesized F-NZVI was observed with a scanning electron microscope (SEM), and the functional groups of the samples were analyzed with Fourier Transform Infrared Spectroscopy (FTIR). Results show that the F-127 was successfully coated on the surface of the NZVI, and that significantly improved the stability of NZVI. Finally, in order to optimize the removal rate of 2,4-dichlorophenol (2,4-DCP) by F-NZVI, three variables were tested: the initial concentration 2,4-DCP, the pH, and the F-NZVI dosage. These were evaluated with a Box-Behnken Design (BBD) of response surface methodology (RSM). The experiments were designed by Design Expert software, and the regression model of fitting quadratic model was established. The following optimum removal conditions were determined: pH = 5, 3.5 g·L−1 F-NZVI for 22.5 mg·L−1 of 2,4-DCP.

Performance and kinetics analysis of an aerobic sequencing batch flexible fibre biofilm reactor for milk processing wastewater treatment

In this study, a sequencing batch flexible fibre biofilm reactor (SB-FFBR) is used for efficient and cost-effective treatment of milk processing wastewater (MPW). The SB-FFBR, modified type of a typical sequencing batch reactor (SBR), is made up of eight bundles of flexible fibre as a supporting media for microorganisms'growth. The working volume and the cycle length of the bioreactor are 8 L and 24 h, respectively. The biological performance of the bioreactor is studied at 10, 3 and 10 various levels of the influent chemical oxygen demand (COD_in; 610-8193 mg L^-1), retention time (RT; 1, 1.6 and 2 days), and organic loading rate (OLR; 0.38-8.19 gCOD m^-3d^-1), respectively. From the results, the minimum COD and total suspended solids (TSS) removal efficiency of 86.8% and 77.3% were achieved at OLR of 8.2 kg COD m^-3d^-1, COD_in of 8193 mg L^-1 and RT of 1 day. While, an excellent COD and TSS removal efficiency were found to be 97.5% and 99.3%, respectively, at low OLR of 0.4 kg COD m^-3d^-1, COD_in of 945 mg L^-1 and RT of 2 days. Furthermore, the kinetic coefficients of COD removal were computed using a first order substrate removal model at different COD concentrations. The first order kinetic constant, (k), was 0.60, 0.65 and 0.357 h^-1 for 500, 810 and 2000 mg COD L^-1, respectively. The use of the flexible fibre as a packing material provided a huge surface area for more microorganism attachment. Therefore, the results demonstrated the SB-FFBR has acted as a suitable and effective strategy in treatment of milk processing industrial wastewater.