Days Of Hydraulic Retention Time Research Articles

Anaerobic co-digestion of food waste and domestic wastewater – Effect of intermittent feeding on short and long chain fatty acids accumulation

Abstract This work investigates the anaerobic co-digestion of a mixture of food waste and domestic wastewater (0.09, v/v) using an upflow anaerobic sludge blanket (UASB) reactor to generate renewable energy in form of biogas. The reactor was operated under the conditions of mesophilic temperature (35 °C), pH 7.2, and 10 days of hydraulic retention time (HRT). The chemical oxygen demand (COD) removal efficiency and the methane content were 80 ± 1.3% and 56%, respectively, when the reactor was operated continuously at the organic loading rate of 2 g COD/L/d in 2 days of operation, while the COD removal efficiency started decreasing and reached 61 ± 1.7% after 10 days, with the methane content of 37%. The deterioration of reactor efficiency on converting organic matter to methane was attributed to the accumulation of long chain fatty acids (LCFAs) onto the sludge. To overcome the physical and metabolic inhibition by LCFAs, the application of intermittent feeding mode (48 h feed and 48 h feedless) was chosen and applied at different organic loading rates (OLRs; 2–4.5 g COD/L/d) to evaluate the reactor performance in terms of COD removal, methane content, accumulation of LCFAs and short chain fatty acids (SCFAs). The COD removal efficiency and methane content were 82 ± 1.1%, 75 ± 0.9%, and 62 ± 1.5% and 58%, 56%, and 51% at the OLR of 2, 3, and 4.5 g COD/L/d, respectively. The 48 h feed/48 h feedless cycle seemed a promising alternative to treat real food wastewater. However, further studies are still necessary to better evaluate the application of intermittent feeding to treat different mixtures of food waste and domestic wastewater at higher organic loading rates.

Biomethanization of the Mixture of Cattle Manure, Pig Manure and Poultry Manure in Co-Digestion with Waste Peels of Pineapple Fruit and Content of Chicken-Gizzard - Part II: Optimization of Process Variables

Background: The indiscriminate discharge of industrial waste, agricultural-biomass waste, waste of municipal, domestic and kitchen waste has negatively impacted on the environment and human health. It is very pertinent to reduce these impacts to the barest minimum through conversion of the waste to useful products. The conversion of these wastes to generate alternative energy to fossil fuel through the technology of anaerobic fermentation is one of the viable and more fascinating options for the management of waste. Objective: To investigate the interactive effect and optimization of process parameters of temperature, total solid content and feed/inoculum ratio on the biomethanization of the mixture of cattle manure, pig manure and poultry manure in co-digestion with waste peels of pineapple fruit and content of chicken-gizzard. Method: Full-factorial central composite design of experiment (RCCD) of the response surface method (RSM) was adopted to assess the possible interactive effects of the process variables and the optimal parameters (i.e. optimization) for biogas/biomethane production in an anaerobic digester. Result: The process variables had a significant (P < 0.05) positive and negative interactive effect on the biomethanization process. A second-order quadratic polynomial regression model which is statistically significant (p < 0.0001) was respectively obtained for cumulative biogas yield (CBY), biomethane content (BC) and hydraulic retention time (HRT). Temperature of 55.2°C; total solid content of 6.25%; and feed/inoculums ratio of 1:2 were found to be the optimum values required to attain a predicted optimum values of 6.261 dm3/g CBY, 71.54% BC within a minimum 8 days of HRT. At this optimum process conditions, the experimental observed maximum CBY, and BC with a minimum HRT were found to be 6.217 dm3/g of slurry, 71.10% and 7 days, respectively. Conclusion: Biogas/biomethane generation through co-substrate anaerobic fermentation of animal waste with waste of fruits constitute a reasonable and applicable renewable energy alternative and this can be optimized through response surface methodology.

Produção de biogás por dejetos de ruminantes e monogástricos co-digeridos com manipueira

Objetivou-se avaliar o uso de manipueira na co-digestão anaeróbia com dejetos de animais monogástricos e ruminantes, por meio de parâmetros de monitoramento do processo e da produção de biogás. Foram utilizados oito biodigestores semicontínuos com volume útil de 7,8 L de substrato em fermentação operados com tempo de retenção hidráulica de 30 dias. Realizou-se análises de pH, nitrogênio amoniacal, alcalinidade parcial (AP), sólidos totais (ST), sólidos voláteis (SV), e rendimento do biogás (m3 kg SVadicionados-1). Os valores de pH e concentrações de AP apresentaram-se na faixa ideal para a ocorrência do processo de digestão, de 6,0 a 8,0 e acima de 1.200 mg·L-1, respectivamente. Durante o processo não houve risco de falência por concentrações de nitrogênio amoniacal. As produções médias de biogás acumuladas semanais foram de 0,00676, 0,1167, 0,01515 e 0,01856 m3, respectivamente para substratos formados por dejetos de bovinos de leite, ovinos, aves e/ou suínos codigeridos com manipueira. Os rendimentos para os respectivos substratos foram 0,122, 0,275, 0,535 e 0,843 m3 kg SVadicionados-1. Maiores produções de biogás são obtidas na co-digestão anaeróbia de dejetos de suínos com 10 % (volume/volume) de manipueira.

Optimization of bio-methanol production from goat manure in single stage bio-reactor

Most of the previous studies only focused on either the production of biogas or liquid fuel, but this study introduces the production of bio-methane and bio-methanol in a batch bio-reactor. The optimization of the process was conducted via response surface method using Design Expert 6.0.10. Proximate and ultimate analysis of the solid waste from papaya peel, banana peel, vegetable waste, leftover rice, bagasse, pineapple peel, goat manure and poultry waste were conducted. The biogas content was analyzed using a gas chromatograph equipped with a thermal conductivity detector (GC-TCD), while bio-fuel was analyzed using High Performance Liquid Chromatography (HPLC). The screening test indicated that waste from goats fed grass and soy pellets was used for the bio-methanol production profiles because this biomass has the highest carbon (36.16%) and volatile solid (12.44 wt%) of the various tested biomass. From the profile analysis, the maximum value of bio-methanol produced is 2.49% with 74.24% of methane. The design of experiments shows that the actual bio-methanol concentration values vary from 0.51 to 5.19 gL−1, and these values are not significantly different from the values (0.45–4.51 gL−1) predicted by the model. The optimal conditions for the production of bio-methanol were temperature of 32.72 °C, 11 days of hydraulic retention time and 0.40 g/L cell concentration for the production of 6.80 gL−1 bio-methanol. The results showed that the goat manure had the most potential for bio-methanol production.

Biochemical passive reactors for treatment of acid mine drainage: Effect of hydraulic retention time on changes in efficiency, composition of reactive mixture, and microbial activity

Biochemical passive treatment represents a promising option for the remediation of acid mine drainage. This study determined the effect of three hydraulic retention times (1, 2, and 4 days) on changes in system efficiency, reactive mixture, and microbial activity in bioreactors under upward flow conditions. Bioreactors were sacrificed in the weeks 8, 17 and 36, and the reactive mixture was sampled at the bottom, middle, and top layers. Physicochemical analyses were performed on reactive mixture post-treatment and correlated with sulfate-reducing bacteria and cellulolytic and dehydrogenase activity. All hydraulic retention times were efficient at increasing pH and alkalinity and removing sulfate (>60%) and metals (85–99% for Fe2+ and 70–100% for Zn2+), except for Mn2+. The longest hydraulic retention time (4 days) increased residual sulfides, deteriorated the quality of treated effluent and negatively impacted sulfate-reducing bacteria. Shortest hydraulic retention time (1 day) washed out biomass and increased input of dissolved oxygen in the reactors, leading to higher redox potential and decreasing metal removal efficiency. Concentrations of iron, zinc and metal sulfides were high in the bottom layer, especially with 2 day of hydraulic retention time. Sulfate-reducing bacteria, cellulolytic and dehydrogenase activity were higher in the middle layer at 4 days of hydraulic retention time. Hydraulic retention time had a strong influence on overall performance of passive reactors.

Hydraulic retention time effects on wastewater nutrient removal and bioproduct production via rotating algal biofilm reactor

Rotating algal biofilm reactor (RABR) technology was successfully employed in an effective strategy to couple the removal of wastewater nutrients with accumulation of valuable bioproducts by grown algae. A secondary stage municipal wastewater was fed to the developed system and the effects of the hydraulic retention time (HRT) parameter on both nutrient removal and bioproduct production were evaluated under fed-batch operation mode. Two sets of bench scale RABRs were designed and operated with HRTs of 2 and 6days in order to provide competitive environment for algal growth. The HRT significantly affected nitrogen and phosphorus uptakes along with lipid and starch accumulations by microalgae in harvested biofilms. Domination of nitrogen removal in 2-day HRT with higher lipid accumulation (20% on dried weight basis) and phosphorus removal in 6-day HRT with higher starch production (27% on dried weight basis) was observed by comparing the performances of the RABRs in duplicate runs.

Addition of Fe2+ increase nitrate removal in vertical subsurface flow constructed wetlands

Fe2+ can assist in the process of denitrification as electron donor to enhance nitrogen removal in constructed wetlands (CWs). In this study, Fe2+ was added to the influent of CWs aiming to investigate the effects of external Fe2+ addition on denitrification efficiency at different carbon/nitrogen (C/N). Community-level physiological profile (CLPP) was assessed according to substrate utilization patterns with Biolog Eco Plates™. Results showed that external Fe2+ remarkably improved the capability of denitrification in constructed wetlands. Nitrate removal rate was largely increased after the addition of 30mg/L Fe2+ to the CWs reactor for a 2-day hydraulic retention time (HRT) at the presence of organic carbon source with low C/N ratio of 2. In reactor without adding organic carbon source, Fe(II)–Fe(III) cycle reaction could not be completed, thus forming hydroxide precipitation leading to low effluent Fe2+ and total iron. However, the enhancement of Fe2+ on denitrification was not obvious at high C/N of 6 and 4 in that organic carbon acted as dominant electron donor in participating denitrification processes. Substrate microbial community structure and diversity in CWs were influenced by organic carbon source and Fe2+. The Shannon, Pielou and Simpson indices in the CWs with external Fe2+ were higher than the control. Principal component analysis (PCA) showed that the CLPPs in constructed wetlands of different influents were significantly different. The constructed wetlands with added organic carbon sources and Fe2+ were grouped together, while the wetlands with the low C/N and the wetlands with high C/N were detached.

Co-digestion of swine excreta associated with increasing levels of crude glycerin

The objective of this research was to evaluate the performance of anaerobic co-digestion of swine excreta associated with increasing doses of crude glycerin and different hydraulic retention times (HRT). A completely randomized design was adopted in a 3 × 4 factorial arrangement composed of three HRT (10, 17, and 24 days) and four crude glycerin doses (0, 5, 10, and 15 g/100 g of total solids [TS]), with four replications per treatment. The assessed parameters were: biogas production potential, reductions of volatile solids (VS), chemical oxygen demand (COD), and most probable number of total and thermotolerant coliforms. The biogas production per added VS presented quadratic effect at 17 and 24 days of HRT, with ideal doses of 5.5 and 5.9 g of crude glycerin/100 g TS, respectively. There was no difference among glycerin doses at 10-day HRT for VS reductions; however, at HRT of 17 and 24 days, there were differences, with greater reduction of 61.1% for 5 g of crude glycerin/100 g TS at 24-day HRT. The COD reduction values showed an effect among retention times, in which the 24-day HRT provided the best results. Reductions in coliforms were greater than 99%, with no difference among treatments. Addition of 5 to 6 g of crude glycerin/100 g TS with a 24-day HRT is more effective in biogas production and reduction of VS, COD, and coliforms from co-digestion of swine excreta.

Performance of the Bio-electrochemical Anaerobic Digestion of Sewage Sludge at Different Hydraulic Retention Times

The performance of bio-electrochemical anaerobic digester, applied with 0.3 V between anode and cathode, for sewage sludge was explored at different hydraulic retention times (HRTs) ranging from 20 to 5 days. The state variables including pH, alkalinity, VFA, and SCOD are quite stable and in suitable ranges for anaerobic digestion. At 20 days of HRT, the performance is considerably high in volatile solids (VS) reduction (70.5%), the specific methane production rate (407 mL L−1 d−1), and the methane content (76.9%) in biogas. The VS reduction and the methane content in biogas slightly deteriorated as the HRT decreased from 20 to 5 days, while the methane production rate increased to 1,339 mL L−1 d−1. The overall energy efficiencies for methane recovery are in the range of 69.1–98.7%, and the maximum energy efficiency appears at 10 days of HRT. These results showed that the bio-electrochemical anaerobic digestion system could obtain much higher VS reduction and energy recovery with shorter HRTs than the con...

Determination of the archaeal and bacterial communities in two-phase and single-stage anaerobic systems by 454 pyrosequencing

2-Phase anaerobic digestion (AD), where the acidogenic phase was operated at 2day hydraulic retention time (HRT) and the methanogenic phase at 10days HRT, had been evaluated to determine if it could provide higher organic reduction and methane production than the conventional single-stage AD (also operated at 12days HRT). 454 pyrosequencing was performed to determine and compare the microbial communities. The acidogenic reactor of the 2-phase system yielded a unique bacterial community of the lowest richness and diversity, while bacterial profiles of the methanogenic reactor closely followed the single-stage reactor. All reactors were predominated by hydrogenotrophic methanogens, mainly Methanolinea. Unusually, the acidogenic reactor contributed up to 24% of total methane production in the 2-phase system. This could be explained by the presence of Methanosarcina and Methanobrevibacter, and their activities could also help regulate reactor alkalinity during high loading conditions through carbon dioxide production. The enrichment of hydrolytic and acidogenic Porphyromonadaceae, Prevotellaceae, Ruminococcaceae and unclassified Bacteroidetes in the acidogenic reactor would have contributed to the improved sludge volatile solids degradation, and ultimately the overall 2-phase system's performance. Syntrophic acetogenic microorganisms were absent in the acidogenic reactor but present in the downstream methanogenic reactor, indicating the retention of various metabolic pathways also found in a single-stage system. The determination of key microorganisms further expands our understanding of the complex biological functions in AD process.

Evaluation of the simultaneous biogas upgrading and treatment of centrates in a high-rate algal pond through C, N and P mass balances

The simultaneous capture of CO2 from biogas and removal of carbon and nutrients from diluted centrates in a 180 L high-rate algal pond (HRAP) interconnected to a 2.5 L absorption column were evaluated using a C, N and P mass balance approach. The experimental set-up was operated indoors at 75 μE/m(2)·s for 24 h/d at 20 days of hydraulic retention time for 2 months of steady state, and supported a C-CO2 removal in the absorption column of 55 ± 6%. Carbon fixation into biomass only accounted for 9 ± 2% of the total C input, which explains the low biomass productivity recorded in the HRAP. In this context, the low impinging light intensity along with the high turbulence in the culture broth entailed a C stripping as CO2 of 49 ± 5% of the total carbon input. Nitrification was the main NH4(+) removal mechanism and accounted for 47 ± 2% of the inlet N-NH4(+), while N removal as biomass represented 14 ± 2% of the total nitrogen input. A luxury P uptake was recorded, which resulted in a P-PO4(-3) biomass content over structural requirements (2.5 ± 0.1%). Phosphorus assimilation corresponded to a 77 ± 2% of the inlet dissolved P-PO4(-3) removed.

THE EFFECT OF BUFFALO DUNG TREATMENT WITH PAUNCH FLUID ON BIOGAS PRODUCTION

Anaerobic digestion is a biological process used to convert organic wastes into biogas and a stable bio-fertilizer for agricultural applications as environmentally friendly product. The produced biogas is used as an alternative renewable energy source. The aim of this study was to analyze the influence of paunch fluid (PF) content on biogas and methane yield from buffalo dung as biowastes. A series of laboratory experiments using 2 L biodigesters (i.e., BD1 till BD6) were carried out in batch operation mode. Each biodigester was fed with fixed 750 g of fresh buffalo dung (D) and mixed with 750 ml of PF and distill water (W) with different ratios (i.e., BD1= 50%, BD2= 50%, BD3= 37.5%, BD4= 37.5%, BD5=0% and BD6= 100% of PF). The results showed that the best performance for biogas and methane production was the biodigester BD3 and BD4 with 37.5% of PF, i.e. biogas yield was 205.8 and 224.2 ml g VS-1, respectively, after 40 days of hydraulic retention time (HRT). While the other biodigesters BD1, BD2, BD5 and BD6 with 50, 50, 0 and 100% of PF delivered a biogas yield of 177.3, 133.1, 172.7 and 0 ml g VS-1, respectively. Additionally, methane production showed the similar performance, i.e. digesters BD4, BD3, BD1, BD5, BD2 and BD6 delivered a methane yield of 144.7, 130.3, 120.4, 104.8, 84.2 and 0.0 ml g VS-1, respectively. These results showed that, the highest biogas and methane yield was delivered when buffalo dung was treated with 37.5% of PF. Although, many references showed that, 50% of PF delivered the highest biogas and methane yields. Therefore, the effect of PF concentration on biogas and methane production must be investigated intensively.

Anaerobic co-digestion of rice straw and digested swine manure with different total solid concentration for methane production

Abstract: This study aimed to investigate potential methane production through anaerobic co-digestion of rice straw and digested swine manure with different total solids. The research was carried out in bench scale with utilizing batch system. To evaluate the stability of anaerobic co-digestion process, the experiment was run in triplicate. The anaerobic co-digestion process was operated in 500 mL batch digesters under constant agitation speed and temperature. The agitation speed was maintained at 270 r/min. Temperature of the batch system was set and maintained at 35oC. Digested swine manure utilized in this experiment was obtained from semi-continuous digesters run at steady state condition, with 25 days of hydraulic retention time under mesophilic condition. Rice straw (RS) generated the highest methane production at 3% total solids (TS) which was around (1814±47.43) mL, where in this concentration, it had C:N ratio at 10.6:1. Rice straw obtained the highest methane yield at 3% TS, which was around (141.4±3.70) mL CH4/g volatile solids (VS) added. Rice straw also had the highest chemical oxygen demand (COD) removal and VS reduction at 3% TS which were around (52.97%±1.46%) and (61.81%±1.04%), respectively. Keywords: anaerobic co-digestion, rice straw, digested swine manure, methane production DOI: 10.3965/j.ijabe.20140706.010 Citation: Darwin, Cheng J J, Liu Z M, Gontupil J, Kwon, O S. Anaerobic co-digestion of rice straw and digested swine manure with different total solid concentration for methane production. Int J Agric & Biol Eng, 2014; 7(6): 79－90.

Using a Hydroponic System with Tall Fescue to Remove Nitrogen and Phosphorus from Renovated Turkey Processing Wastewater

Abstract. Rising nitrogen and phosphorus related nutrient pollution in different aquifers, as indicated by the deterioration of water quality, triggered this study. The aim of this study was to use commercially valuable ornamental plants, such as tall fescue, for wastewater treatment without decreasing the overall treatment efficiencies of a laboratory-scale hydroponic (soilless) system. Renovated turkey processing wastewater, from a sand bioreactor treatment system at a turkey processing plant, was used in this experiment. Nitrate and phosphate were measured in influent and effluent of the hydroponic system to evaluate the nutrient removal efficiency. Tall fescue was cultured on media consisting of perforated plastic plates and one layer of burlap. Water samples were tested at 12 h intervals under 2-day hydraulic retention times. Average removals of 53% nitrate and 68% soluble reactive phosphate were achieved at 48 h under 2-day hydraulic retention time. The 2-day retention time was optimal for nutrient removal at 22 to 28 days of growth. The plant nutrient content was also determined. The tall fescue hydroponic system, including possible microbial participation, accounted on average for 14% nitrate-N and 42% P removal. Improvement in the efficiencies could come from a better understanding of the biological mechanisms and controls of nutrient removal.

Valorization of residues from refining of used vegetable oils

This study investigates the advantages of two-phase anaerobic digestion for treating a mixture (1/5 v/v) of used vegetable oils processing wastes and pig manure using two semi-continuous digesters operated at mesophilic temperature (37±1 oC). The experiments were conducted at hydraulic retention times (HRT) of 0.5, 1, 2 and 4 days in the first stage (acidifier) and at HRT of 11.5, 15, 18 and 20 days in the second stage (methanizer). The results revealed that the HRT had a high influence on the soluble chemical oxygen demand (CODs) and total dissolved solids (TDS) removal. The maximum total CODs removal efficiency of 86.4% and TDS removal efficiency of 81.9% was achieved at 20 days of global HRT. The maximum biogas production of 0.65 m 3 per kilogramme of volatile dissolved solids (VDS) removed (65% CH4) was also achieved at 20 days of HRT.

Evaluation of Aerobic and Anaerobic Co-Digestion of <i>Tetraselmis suecica </i>and Oil Palm Empty Fruit Bunches by Response Surface Methodology

This study investigated co-cultivation of Tetraselmis suecica microalgae with Oil Palm empty fruit bunch (OPEFB) for anaerobic biomethane production and Palm oil mill effluent (POME) treatment. The highest specific biogas production (0.1162 m3 kg-1 COD day-1) and biomethane yield (3900.8 mL CH4 L-1 POME day-1) was achieved with microalgae at 2 mL mL-1 POME, and OPEFB at 0.12 g mL-1 POME. Without co-digestion of microalgae, higher specific biogas production (0.1269 m3 kg-1 COD day-1) but lower biomethane yield (3641.8 mL CH4 L-1 POME day-1) were observed. Second order polynomial model fits the data well with less than 5% error. Higher removal efficiency (62-95%) of COD, BOD, TOC and TN were achieved by aerobic and anaerobic treatment of POME with microalgae than without microalgal treatment after 3 and 7 days of hydraulic retention time (HRT).

Two-phase anaerobic co-digestion of used vegetable oils’ wastes and pig manure

The purpose of this work was to study the anaerobic co-digestion of all the by-products generated during the processing of used vegetable oils (UVO) with the objective of proposing a solution for the treatment of these wastes. More specifically, this study investigates the advantages of two-phase anaerobic digestion for treating a mixture (1/5 v/v) of UVO processing wastes (OW) and pig manure (PM) using two semi-continuous digesters operated at mesophilic temperature (37 ± 1 °C). The experiments were conducted at hydraulic retention time (HRT) of 0.5, 1, 2 and 4 days in the first stage (acidifier) and at HRT of 11.5, 15, 18 and 20 days in the second stage (methaniser). The results revealed that the HRT had a high influence on the soluble chemical oxygen demand (sCOD) and total dissolved solids (TDS) removal. The maximum total sCOD removal efficiency of 86.4 % and TDS removal efficiency of 81.9 % was achieved at 20 days of global HRT. The maximum biogas production of 0.65 m3 per kilogramme of volatile dissolved solids (VDS) was removed, corresponding to a methane production of 0.42 m3 CH4 kg−1. VDS removed (65 % CH4) was also achieved at 20 days of HRT. The two-phase digestion system showed good stability, which was mainly attributed to the strong buffering capacity with the two-phase system and the high alkalinity from PM when co-digested with OW. The results obtained from this study provide fundamental information for scaling up a high-performance two-phase anaerobic system in the future.

Anaerobic Baffled Reactor 공정을 이용한 1차 슬러지 산발효에 대한 연구

A lab-scale Anaerobic Baffled Reactor (ABR) was applied to treat a primary sludge taken from a municipal wastewater treatment plant. In this experiment, acidogenic reaction was promoted by operating the ABR with short hydraulic retention time (HRT) to produce sufficient volatile fatty acids (VFA) instead of production of methane. The performance of ABR on the VFA production and total solids reduction was observed with different operating conditions with 2, 4, 6, and 8 days of HRT. Corresponding organic loading rates were 6.7, 3.4, 2.2, and <TEX>$1.6kgCOD_{cr}/m^3{\cdot}day$</TEX>. As HRT increased the removal rate of TCOD was also increased (82.5, 84.2, 96.9, and 95.9 % in average for HRT of 2, 4, 6, and 8 days, respectively) because the settlement of solids was enhanced in the baffle by the decrease of upflow velocity. At HRT of 2 days the average concentration of VFA in the effluent was measured at <TEX>$1,306{\pm}552$</TEX> mgCOD/L corresponding to 107 % increment as compared to the VFA concentration in the influent. However, as HRT increased VFA concentraiotn was decreased to <TEX>$143{\pm}552$</TEX> mgCOD/L at HRT of 8 days. The reduction rates of total solids were 12.2, 26.5, 24.8, and 43.0 % for HRT of 2, 4, 6, and 8 days. As HRT increased the hydrolysis of organic particulate matters in the reactor was enhanced due to the increasing of solids retention time in the baffle zone with low upflow velocity in long HRT condition. Consequently, we found that a primary sludge became a good source of VFA production by the application of ABR process with HRT less than 4 days and the 12-26 % of total solids reduction was expected at these conditions.

An efficient biotreatment process for polyvinyl alcohol containing textile wastewater

The aim of this work was to optimize the biodegradation of polyvinyl alcohol (PVA) containing actual textile wastewater for a sustainable treatment solution. The isolated microbial consortia of effective PVA degrader namely Candida Sp. and Pseudomonas Sp., which were responsible for symbiotic degradation of chemical oxidation demand (COD) and PVA from desizing wastewater. In the process optimization, the maximum aeration was essential to achieve a high degradation rate, where as stirring enhances further degradation and foam control. Batch experiments concluded with the need of 16 lpm/l and 150 rpm of air and stirring speed respectively for high rate of COD and PVA degradation. Optimized process leads to 2 days of hydraulic retention time (HRT) with 85–90% PVA degradation. Continuous study also confirmed above treatment process optimization with 85.02% of COD and 90.3% of PVA degradation of effluent with 2 days HRT. This study gives environment friendly and cost effective solution for PVA containing textile wastewater treatment.

Assessment of sewage sludge bioremediation at different hydraulic retention times using mixed fungal inoculation by liquid-state bioconversion

Sustainable, environmental friendly, and safe disposal of sewage treatment plant (STP) sludge is a global expectation. Bioremediation performance was examined at different hydraulic retention times (HRT) in 3-10 days and organic loading rates (OLR) at 0.66-7.81 g chemical oxygen demand (COD) per liter per day, with mixed filamentous fungal (Aspergillus niger and Penicillium corylophilum) inoculation by liquid-state bioconversion (LSB) technique as a continuous process in large-scale bioreactor. Encouraging results were monitored in treated sludge by LSB continuous process. The highest removal of total suspended solid (TSS), turbidity, and COD were achieved at 98, 99, and 93%, respectively, at 10 days HRT compared to control. The minimum volatile suspended solid/suspended solid implies the quality of water, which was recorded 0.59 at 10 days and 0.72 at 3 days of HRT. In treated supernatant with 88% protein removal at 10 days of HRT indicates a higher magnitude of purification of treated sludge. The specific resistance to filtration (SRF) quantifies the performance of dewaterability; it was recorded minimum 0.049 × 10(12) m kg(-1) at 10 days of HRT, which was equivalent to 97% decrease of SRF. The lower OLR and higher HRT directly influenced the bioremediation and dewaterability of STP sludge in LSB process. The obtained findings imply encouraging message in continuing treatment of STP sludge, i.e., bioremediation of wastewater for environmental friendly disposal in near future.