Wastewater Pond Research Articles

Simultaneous heterotrophic nitrification and aerobic denitrification at high initial phenol concentration by isolated bacterium Diaphorobacter sp. PD-7

A strain capable of phenol degradation, heterotrophic nitrification and aerobic denitrification was isolated from activated sludge of coking-plant wastewater ponds under aerobic condition. Based on its morphology, physiology, biochemical analysis and phylogenetic characteristics, the isolate was identified as Diaphorobacter sp. PD-7. Biodegradation tests of phenol showed that the maximum phenol degradation occurred at the late phase of exponential growth stages, with 1400mg·L−1 phenol completely degraded within 85h. Diaphorobacter sp. PD-7 accumulated a vast quantity of phenol hydroxylase in this physiological phase, ensuring that the cells quickly utilize phenol as a sole carbon and energy source. The kinetic behavior of Diaphorobacter sp. PD-7 in batch cultures was investigated over a wide range of initial phenol concentrations (0–1400mg·L−1) by using the Haldane model, which adequately describes the dynamic behavior of phenol biodegradation by strain Diaphorobacter sp. PD-7. At initial phenol concentration of 1400mg·L−1, batch experiments (0.25L flask) of nitrogen removal under aerobic condition gave almost entirely removal of 120.69mg·L−1 ammonium nitrogen within 75h, while nitrate nitrogen removal reached 91% within 65h. Moreover, hydroxylamine oxidase, periplasmic nitrate reductase and nitrite reductase were successfully expressed in the isolate.

Determination of Pharmaceuticals and Personal Care Product Components in Wastewater Using Capillary Electrophoresis Coupled with Solid Phase Extraction

Four pharmaceuticals and personal care product components including salbutamol sulfate, cimetidine, ibuprofen, and carbamazepine are difficult to separate by conventional high-performance liquid chromatography. In this work, a method using solid phase extraction sample preparation and capillary electrophoresis with ultraviolet detection was developed for the determination of these compounds in wastewater. Separation parameters were optimized, and under these conditions (20 mM phosphate solution at pH 6.70 as the running buffer, 10 mM phosphate with 20% v/v methanol as sample solvent), the analytes were well separated. This method showed good linearity from 3.0 to 20.0 mg/L, detection limits of 1.3 to 2.9 µg/L, and relative standard deviation values less than 5% for n = 7. Wastewater and local pond water were analyzed. The recoveries of the analytes in wastewater were between 89.7 and 108%. Carbamazepine was detected in the influent and effluent from the wastewater plant (329.30, 291.94 µg/L) and pond water (91.87 µg/L). The results demonstrated that the developed method may serve as alternative method for the determination of these compounds.

Biodiesel Production from Waste Coconut Oil in Coconut Milk Manufacturing

The purpose of this research was to develop a 3 step biodiesel production from waste coconut oil taken from a wastewater pond in a coconut milk manufacturing plant. Special attention was paid to optimizing the first step, acid catalyzed hydrolysis, to convert the waste coconut oil into high free fatty acid oil, 83.32 wt%. The first step was the acid hydrolysis, in order to produce high free fatty acid oil. The optimum condition in acid hydrolysis was 5 % by mass of hydrochloric acid, in order to produce high free fatty acid oil that could be used as raw material for biodiesel production. The second step was the acid esterification, in order to reduce the FFA and convert FFA to methyl ester. The reduction of the FFA from 83.32 % in high free fatty acid oil to less than 2 % required 3 % by mass of hydrochloric acid, a molar ratio of methanol to oil of 10: 1, and a reaction time of 60 min. The alkaline transesterification in the third step was used triglyceride at 1.0wt% of KOH for catalysis, a molar ratio of methanol to oil of 6:1, and a reaction time of 60 min. The waste coconut oil biodiesel was further evaluated by determining its fuel quality, and most of the properties were well within ASTM and EN standards.doi:10.14456/WJST.2015.24

Immobilized periphytic cyanobacteria for removal of nitrogenouscompounds and phosphorus from shrimp farm wastewater

Cyanobacteria can be used to remove nitrogenous compounds from wastewater, but a major bottleneck in the process is the separation of cyanobacterial biomass from the treated water discharge, which may cause eutrophication. The current study assessed the suitability of three periphytic cyanobacteria (Geitlerinema sp., Gloeotrichia sp., and Lyngbya sp.) isolated from shrimp ponds. These cyanobacteria were immobilized by self-adhesion to polyvinyl chloride sheets, forming mats, and were screened for their efficacy to reduce nitrogenous compounds and phosphorus. Among the three isolates, Geitlerinema sp. showed the highest reduction rate (98%) and was further tested using shrimp pond wastewater. The results showed that initial wastewater concentrations (mg L-1) of total ammonia nitrogen (5.0), nitrite nitrogen (2.9), and soluble reactive phosphorus (2.5) were significantly (P < 0.05) reduced within 7 days in tanks containing wastewater + Geitlerinema sp. mats (0.1, 0.2, and 0.8) compared to wastewater + substrate only (4.3, 2.7, and 2.3) or wastewater only (4.4, 2.8, and 2.4). In addition, Geitlerinema sp. was found to be nontoxic to Artemia. Fast and effective sequestration of nutrients from wastewater by the Geitlerinema mats, as well as ease of harvesting from the mats, make this treatment an attractive alternative for wastewater treatment.

Sustainable Approach to Wastewater Management in the Federal University of Technology, Akure, Nigeria

Proper disposal of wastewater still remains a major concern in developing countries. As population grows and urbanization increases, more wastewater is generated and there is great awareness on the health and environmental implication of poorly disposed wastewater. This research work develops a sustainable approach to wastewater disposal in the Federal University of Technology, Akure. The existing wastewater disposal system in use in the study area is the septic tank - soakaway system for individual buildings. This approach presents serious problems due to the choice of inappropriate technology, improper siting of infrastructure, lack of adherence to correct design concepts and lack of proper maintenance.Wastewater samples were collected and their properties determined through laboratory tests to ascertain the concentrations of significant physical, chemical and bacteriological constituents for the selection of appropriate wastewater treatment processes. The total estimate of the wastewater generated from various locations was 2.075 million liters per day based on the population of approximately 26,131.Taking into consideration the available pipe sizes in the market a pipe size of 100 mm was found to be suitable for wastewater conveyance from the office and residential areas based on the contributory population. The proposed wastewater treatment plant (three anaerobic ponds of 57.42 m x19.14 m x5 m connected in series) is to be sited at the lowest topographical level which is of suitable distance from the office and residential areas. Implementing this wastewater management approach in the university will mitigate the negative effect of septic tank - soakaway system and present an environmentally sustainable wastewater management approach. Keywords: Wastewater, disposal methods, septic tank, soakaway and anaerobic pond

Esterification of Waste Palm Oil in Wastewater Pond for Community Biodiesel Production

The aim of this research was to develop a two-step technique to prepare biodiesel from waste palm oil (WPO) with high free fatty acid content. The developed process consists of esterification and transesterification steps. Response surface methodology (RSM) was applied for investigating the experimental design for esterification step. Design of experiment was performed by application of 5-levels-3-factors central composite design in order to study the optimum condition for decreasing FFA in WPO. The WPO with low FFA was further experimented in transesterification step to obtain fatty acid methyl ester (FAME). The investigated results showed that the WPO containing 48.62%wt of high FFA. The optimum condition of esterification step was 28 moles of methanol to FFA in WPO molar ratio, 5.5% sulfuric acid concentration in 90 min of reaction time and 60 °C of reaction temperature. After transesterification step, WPO biodiesel gave methyl ester content at 84.05% according to EN 14103 method. The properties of WPO methyl ester meet the standards of Thailand community biodiesel that can be used as fuel in agricultural machine.

Use of Waste Coconut Oil Obtained from Waste Water Pond of Coconut Milk Plant to Produce Biodiesel

Waste coconut oil obtained from waste water pond contains high free fatty acid (FFA) which is not suitable to produce biodiesel via transesterification. The two steps of reaction (esterification and transesterification) were used to produce biodiesel from waste coconut oil. The result showed that FFA decreased from 92.95%wt to nearby 2%wt under the conditions of 80%vol of methanol to oil, 4%wt of hydrochloric acid and 4 h of reaction time in esterification step. In addition 95.34%wt conversion of fatty acid methyl ester (FAME) could be achieved in 1 h when 20%vol methanol to oil and 0.5%wt of sodium hydroxide in transesterification step. The fuel properties of waste coconut oil biodiesel were mostly met well within the ranges specified in biodiesel standard.

The Belmont Valley integrated algae pond system in retrospect

Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald-designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect sewage treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation, and affords secondarily treated water for reclamation according to its design specifications, which most closely resemble those of the AIWPS Advanced Secondary Process. In this paper IAPS as a municipal sewage treatment technology is re-examined in relation to design and operation, the underpinning biochemistry of nutrient removal by algae is described, and a retrospective is provided on the demonstration system at the Belmont Valley WWTW. In addition to presenting details of the process flow, several shortcomings and/or oversights are highlighted and, in particular, the need for an appropriate tertiary treatment component. However, despite the use of IAPS for sewage treatment in many countries, this technology is still viewed with some scepticism. Thus, a major purpose of this overview is to provide a synthesis of available information on IAPS and an appraisal of its use for municipal sewage treatment. Keywords : advanced integrated wastewater pond system, integrated algae pond systems, wastewater, algae, nutrient removal, sewage

The impacts of a linear wastewater reservoir on groundwater recharge and geochemical evolution in a semi-arid area of the Lake Baiyangdian watershed, North China Plain

Sewage leakage has become an important source of groundwater recharge in urban areas. Large linear wastewater ponds that lack anti-seepage measures can act as river channels that cause the deterioration of groundwater quality. This study investigated the groundwater recharge by leakage of the Tanghe Wastewater Reservoir, which is the largest industrial wastewater channel on the North China Plain. Additionally, water quality evolution was investigated using a combination of multivariate statistical methods, multi-tracers and geochemical methods. Stable isotopes of hydrogen and oxygen indicated high levels of wastewater evaporation. Based on the assumption that the wastewater was under an open system and fully mixed, an evaporation model was established to estimate the evaporation of the wastewater based on isotope enrichments of the Rayleigh distillation theory using the average isotope values for dry and rainy seasons. Using an average evaporation loss of 26.5% for the input wastewater, the estimated recharge fraction of wastewater leakage and irrigation was 73.5% of the total input of wastewater. The lateral regional groundwater inflow was considered to be another recharge source. Combing the two end-members mix model and cluster analysis revealed that the mixture percentage of the wastewater decreased from the Highly Affected Zone (76%) to the Transition Zone (5%). Ion exchange and redox reaction were the dominant geochemical processes when wastewater entered the aquifer. Carbonate precipitation was also a major process affecting evolution of groundwater quality along groundwater flow paths.

Seasonal variation and impact of waste-water lagoons as larval habitat on the population dynamics of Culicoides sonorensis (Diptera:Ceratpogonidae) at two dairy farms in northern California.

The Sacramento (northern Central) Valley of California (CA) has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV) and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012– to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice) along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the “overwintering” of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual abundance and dispersal of Culicoides midges is essential for the creation of models to predict BTV infection of livestock and to develop sound abatement strategies.

Removal of naphthenic acids using adsorption process and the effect of the addition of salt

In this study, various types of adsorbents were examined for the removal of Naphthenic acids (NAs) in the preliminary stage of this study. Among them, activated carbon and nickel (Ni) based alumina (Ni-Al2O3) possess relatively high adsorption capacity of NAs. The removal of NAs was evaluated comparing the total organic carbon (TOC) of the solution before and after the adsorption process. The effect of Ni loading was investigated using Ni-Al2O4 with various nickel loadings. The highest adsorption capacity (20 mg of TOC/1 mg of adsorbent) was belong to Ni-Al2O4 with 10.7% Ni loading. By the addition of salt (1500 ppm NaCl) to NAs solutions having concentrations from of 15 to 38 ppm, it was observed that the adsorption decreased dramatically (up to 80%) depending on the concentration of TOC. The kinetics of the adsorption of TOC on Ni-based alumina was also investigated. The decrease of TOC was more that 40% in the first half hour, indicating that adsorption was very rapid in the beginning. The adsorption increased slightly for up to 5 h and then leveled off when the TOC reached to 50% of initial TOC concentration. However, when sodium chloride (NaCl) was added to the solution, the adsorption decreased to almost 9% within the first half hour, reaching to almost 5% after 3 h. These phenomena suggest that the effectiveness of adsorbents may be improved by decreasing the total dissolved salts in tailings pond wastewater.

The effect of aeration and effluent recycling on domestic wastewater treatment in a pilot-plant system of duckweed ponds

Three pilot-scale duckweed pond (DP) wastewater treatment systems were designed and operated to examine the effect of aeration and effluent recycling on treatment efficiency. Each system consisted of two DPs in series fed by pre-settled domestic sewage. The first system (duckweed+ conventional treatment) was 'natural' and included only duckweed plants. The second system (duckweed aeration) included aeration in the second pond. The third system (duckweed+ aeration+ circulation) included aeration in the second pond and effluent recycling from the second to the first pond. All three systems demonstrated similarly efficient removal of organic matter and nutrients. Supplemental aeration had no effect on either dissolved oxygen levels or on pollutant removal efficiencies. Although recycling had almost no influence on nutrient removal efficiencies, it had a positive impact on chemical oxygen demand and total suspended solids removals due to equalization of load and pH, which suppressed algae growth. Recycling also improved the appearance and growth rate of the duckweed plants, especially during heavy wastewater loads.

Trace Metals in Surface Soil Contaminated by Release of Phosphate Industry in the Surroundings of Sfax-Tunisia

There is a worldwide growing concern about soil pollution caused by phosphate industry creating thus large amounts of phosphogypsum slurry. This slurry is piped from the processing facilities up into acidic wastewater ponds that sit atop the mountainous waste piles known as gypsum stacks. This issue is of special interest because of toxic metals threats to groundwater tables as well as to the surrounding environment. There is a worldwide growing concern about soil pollution caused by phosphate industry creating thus large amounts of phosphogypsum slurry. This slurry is piped from the processing facilities up into acidic wastewater ponds that sit atop the mountainous waste piles known as gypsum stacks. This issue is of special interest because of toxic metals threats to groundwater tables as well as to the surrounding environment. The aim of the present work is to assess the level of trace elements content in soil around stocked solid waste “a phosphogypsum” derived from a former phosphate fertilizers factory and to investigate their factors of variation. Twenty soil samples were collected at the depths of 20 cm and analyzed for their physicochemical properties, the content of their major elements (Ca, Mg, K, Na, Al, Fe, Mn), and some trace elements such as Zn, Pb, Cr, Cu, Co and Ni. Data were processed with multivariate statistical analysis in order to investigate relationships among the trace elements and the factors controlling their distribution in the phosphogypsum surrounding environment. Enrichment factors (EF) were calculated to assess either natural and/or anthropogenic origins. The results indicate moderate levels of contamination and big differences in variability among elements. The maximal and mean concentrations found in soil, except the soil sample S5.1, were 95.2 and 36.5 mg Kg -1 for Zn, 75.2 and 30.23 mg Kg -1 for Pb, 28.4 and 17.5 mg Kg -1 for Cr, 61.9 and 15.6 mg Kg -1 for Cu, 5.28 and 2.7 mg Kg -1 for Co, and 13.2 and 6.4 mg Kg -1 for Ni. Most of the elements were positively correlated with pH and cation-exchange capacity, and no correlation with total organic carbon and electrical conductivity except for Cu, Zn and Pb was found. The EF values of the most trace metals were higher than 1.5 indicating that the phosphate fertilizer industry had an anthropogenic effect causing a negative impact on the environment. The relatively increased amount of toxic metals in the examined soils requires the area to be controlled since a variety of agricultural activities are conducted nearby moreover the surroundings are programmed to be residential zones. DOI: http://dx.doi.org/10.5755/j01.erem.65.3.4865

Settling and bioflocculation of two species of algae used in wastewater treatment and algae biomass production

The settling and bioflocculation of two strains of algae were investigated in the laboratory to provide insights to help improve algae settling in large‐scale, algae‐based wastewater treatment systems with simultaneous algae biofuel production. Energy‐efficient algae harvesting methods are needed for cost‐competitive production of biofuels from algae. The use of bacterially derived exudates (bioflocculation) is promising, but its use in high‐rate algae pond (HRAP) wastewater systems has not yielded consistently reliable settling. The settling of the algae species Scenedesmus sp. and Chlorella vulgaris was investigated in the laboratory with and without cultures of the bacterium Burkholderia cepacia to investigate environmental effects on the settling of pure algal cultures and to examine possible bioflocculation by bacteria and bacterial exudates. Scenedesmus sp. and C. vulgaris responded in opposite ways to changes in operating conditions such as culture age and bioflocculation. Scenedesmus sp. settled better in later stationary growth stages, while C. vulgaris settled better in its early exponential growth phase. Scenedesmus sp. settling was improved by bioflocculation during early exponential and late stationary growth stages, but not during early stationary growth. Scenedesmus sp. responded better to B. cepacia cells plus filtrate (filtered bacterial broth) than to filtrate addition alone. In contrast, C. vulgaris settling was not improved via bioflocculation with neither the addition of B. cepacia cells nor filtrate at any growth stage. Longer contact time between the algae cells and bioflocculants improved the settling of Scenedesmus sp., but not the settling of C. vulgaris. Observed differences in settling and bioflocculation of the two algae species were attributed to differences in algal cell size and shape, culture density, and exudate type (i.e., capsular versus dissolved EPS). The widely different settling behavior of the two species of algae used in this research may explain the often varied results observed with mixed cultures in algae wastewater ponds. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 946–954, 2013

CFD study to determine the optimal configuration of aerators in a full-scale waste stabilization pond

Aerated lagoons (ALs) are important variants of the pond wastewater treatment technology that have not received much attention in the literature. The hydraulic behaviour of ALs and especially the Facultative aerated lagoons (FALs) is very complex since the aeration in these systems is designed for oxygen transfer but not necessarily to create complete mixing. In this work, the energy expenditure of the aerators was studied by means of a scenario analysis. 3D CFD models (one phase and multiphase) of a 3 ha FAL in a waste stabilization pond system in Cuenca (Ecuador) were built for different configurations of aerators. The thrust produced by the aerators was modelled by an external momentum source applied as velocity vectors into the pond fluid. The predictions of a single phase model were in satisfactory agreement with experimental results. Subsequently, a scenario analysis assessing several aeration schemes with different numbers of aerators in operation were tested with respect to velocity profiles and residence time distribution (RTD) curves. This analysis showed that the aeration scheme with all 10 aerators switched on produces a similar hydraulic behaviour compared to using only 6 or 8 aerators. The current operational schemes comprise of switching off some aerators during the peak hours of the day and operating all 10 aerators during night. This current practice could be economically replaced by continuously operating 4 or 6 aerators without significantly affecting the overall mixing. Furthermore, a continuous mixing regime minimises the sediment oxygen demand enhancing the oxygen levels in the pond.

Using wastewater and high-rate algal ponds for nutrient removal and the production of bioenergy and biofuels

This paper projects a positive outcome for large-scale algal biofuel and energy production when wastewater treatment is the primary goal. Such a view arises partly from a recent change in emphasis in wastewater treatment technology, from simply oxidising the organic matter in the waste (i.e. removing the biological oxygen demand) to removing the nutrients - specifically nitrogen and phosphorus - which are the root cause of eutrophication of inland waterways and coastal zones. A growing need for nutrient removal greatly improves the prospects for using new algal ponds in wastewater treatment, since microalgae are particularly efficient in capturing and removing such nutrients. Using a spreadsheet model, four scenarios combining algae biomass production with the making of biodiesel, biogas and other products were assessed for two of Australia's largest wastewater treatment plants. The results showed that super critical water reactors and anaerobic digesters could be attractive pathway options, the latter providing significant savings in greenhouse gas emissions. Combining anaerobic digestion with oil extraction and the internal economies derived from cheap land and recycling of water and nutrients on-site could allow algal oil to be produced for less than US$1 per litre.

Euglena sp. as a suitable source of lipids for potential use as biofuel and sustainable wastewater treatment

Prolific algal growth in sewage ponds with high organic loads in the tropical regions can provide cost-effective and efficient wastewater treatment and biofuel production. This work examines the ability of Euglena sp. growing in wastewater ponds for biofuel production and treatment of wastewater. The algae were isolated from the sewage treatment plants and were tested for their nutrient removal capability. Compared to other algae, Euglena sp. showed faster growth rates with high biomass density at elevated concentrations of ammonium nitrogen (NH4-N) and organic carbon (C). Profuse growth of these species was observed in untreated wastewaters with a mean specific growth rate (mu) of 0.28 day(-1) and biomass productivities of 132 mg L-1 day(-1). The algae cultured within a short period of 8 days resulted in the 98 % removal of NH4-N, 93 % of total nitrogen 85 % of ortho-phosphate, 66 % of total phosphate and 92 % total organic carbon. Euglenoids achieved a maximum lipid content of 24.6 % (w/w) with a biomass density of 1.24 g L-1 (dry wt.). Fourier transform infrared spectra showed clear transitions in biochemical compositions with increased lipid/protein ratio at the end of the culture. Gas chromatography and mass spectrometry indicated the presence of high contents of palmitic, linolenic and linoleic acids (46, 23 and 22 %, respectively), adding to the biodiesel quality. Good lipid content (comprised quality fatty acids), efficient nutrient uptake and profuse biomass productivity make the Euglena sp. as a viable source for biofuel production in wastewaters.

Greenhouse Gas and Ammonia Emissions from an Open-Freestall Dairy in Southern Idaho

Concentrated dairy operations emit trace gases such as ammonia (NH), methane (CH), and nitrous oxide (NO) to the atmosphere. The implementation of air quality regulations in livestock-producing states increases the need for accurate on-farm determination of emission rates. Our objective was to determine the emission rates of NH, CH, and NO from the open-freestall and wastewater pond source areas on a commercial dairy in southern Idaho using a flush system with anaerobic digestion. Gas concentrations and wind statistics were measured and used with an inverse dispersion model to calculate emission rates. Average emissions per cow per day from the open-freestall source area were 0.08 kg NH, 0.41 kg CH, and 0.02 kg NO. Average emissions from the wastewater ponds (g m d) were 6.8 NH, 22 CH, and 0.2 NO. The combined emissions on a per cow per day basis from the open-freestall and wastewater pond areas averaged 0.20 kg NH and 0.75 kg CH. Combined NO emissions were not calculated due to limited available data. The wastewater ponds were the greatest source of total farm NH emissions (67%) in spring and summer. The emissions of CH were approximately equal from the two source areas in spring and summer. During the late fall and winter months, the open-freestall area constituted the greatest source area of NH and CH emissions. Data from this study can be used to develop trace gas emissions factors from open-freestall dairies in southern Idaho and other open-freestall production systems in similar climatic regions.

Effects of Hydraulic Retention Time on Organic and Nitrogen Removal in a Sponge-Membrane Bioreactor

This is the first study on application of a sponge-membrane bioreactor (sponge MBR) for recirculation of aquaculture wastewater in the Mekong delta, Vietnam. Performance of a sponge MBR with a moving-cube sponge medium (20% v/v) was evaluated at different hydraulic retention times (HRTs) for the specific example of catfish pond wastewater. The sponge MBR was operated at HRT values of 8, 4, and 2 h, which correspond to membrane fluxes of 5, 10, and 20 L/m2 per hour, respectively. The average chemical oxygen demand (COD) removal efficiencies were maintained at 93%, 94%, and 87% at an HRT of 8, 4, and 2 h, respectively, while the average total nitrogen (TN) removal efficiencies were 84%, 70%, and 57%. The COD and TN removal efficiencies decreased with a decrease in HRT (increase in membrane flux). Permeate concentrations of COD and TN were as low as 6.3 and 2.7 mg/L at the operated HRTs, respectively. Compared to the conventional MBR, the sponge MBR had twice the TN removal capacity at the same HRT due to simultaneous nitrification–denitrification. In addition, results implicated that the fouling rate (dTMP/dt) increased in an inverse proportion with HRT (h) according to the power equation (fouling rate=4.2474 HRT−2.225). Free movement of sponges in the reactor improved fouling due to sweeping of the cake layer on the membrane surface. Results reveal that the sponge MBR was effective in terms of simultaneous organic and nitrogen removal, fouling control, and water recirculation.

Synthesis of Wax Esters from Crude Fish Fat by Lipase of Burkholderia sp. EQ3 and Commercial Lipases

AbstractThe lipase from Burkholderia sp. EQ3 was used to synthesize wax esters in comparison with commercial lipases. The supernatant of Burkholderia sp. EQ3 was collected from a liquid basal medium with 1 % fish oil after 12 h cultivation (1.90 U/ml of lipase activity). The crude lipase was prepared by acetone precipitation of the culture supernatant (4.70 U/mg and 9.40 purification folds). The crude fish fat obtained by hexane extraction of waste fat from the wastewater pond of a canned tuna factory and cetyl alcohol were used for wax esters synthesis. Five commercial lipases were screened in comparison with crude lipase from Burkholderia sp. EQ3 in wax esters synthesis. The optimum conditions for wax esters synthesis from crude fish fat using Novozyme 435 were enzyme 1 U, substrate molar ratio of crude fish fat to cetyl alcohol 1:2 (115.30 mg of crude fish fat and 66.67 mg of cetyl alcohol) in hexane at 37 °C and 200 rpm with 90.81 % (TLC–FID peak area) after one h of reaction. The optimum conditions for the synthesis by crude lipase from Burkholderia sp. EQ3 were crude lipase 40 U, substrate molar ratio of crude fish fat and cetyl alcohol 1:2 in isooctane at 30 °C and 200 rpm with 95.07 % (TLC–FID peak area) after 6 h of reaction. The synthesized wax esters were mainly composed of cetyl palmitate and cetyl oleate.