Demulsification techniques of water-in-oil and oil-in-water emulsions in petroleum industry

The difficulties associated with transportation and refining of crude oil emulsions and produced water discharge limitations are among the conspicuous clues that have led the oilfield researchers to probe into practical demulsification methods for many decades. Inconsistent research outcomes observed in the literature for a particular demulsification method of a typical emulsion (i.e., water-in-oil or oil-in-water) arise not only from the varied influential parameters associated (such as salinity, temperature, pH, dispersed phase content, emulsifier/demulsifier concentration, and droplet size) but also from the diverse types of emulsion constituents (namely oil, surfactant, salt, alkali, polymer, fine solids, and/or other chemicals/impurities). Being the main component in formation of stabilizing interfacial film surrounding the dispersed phase droplets, surfactant is the most predominant contributor to emulsion stability, extent of which depends on its nature (being ionic or nonionic, and its degree of hydrophilicity/lipophilicity), concentration, and interaction with other surface-active agents in the emulsion as well as on the salinity, temperature, and pH of the system. In this paper, it is endeavored to overview some of the most commonly exploited demulsification techniques (i.e., chemical, biological, membrane, electrical, and microwave irradiation) of both oilfield and synthetic emulsions, taking into account the emulsion-stabilizing and -destabilizing effects with regard to the dominant parameters plus the emulsion composition. Further, the variations occurring in interfacial properties of emulsions by demulsification process are discussed. Finally, the mechanism(s) involved in emulsions resolution achieved by each method is elucidated. Clearly, the most efficient demulsification approach is the one able to attain desirable separation efficiency while complying with the environmental regulations and imposing the least economic burden on the petroleum industry

Liquid state bioconversion of sewage treatment plant sludge in batch fermenter and shake flask

A study on liquid state bioconversion of sewage treatment plant (STP) sludge was assisted to evaluate the performance of batch fermenter compared to shake flask in a laboratory. Bioconversion of STP sludge was highly influenced by the mixed fungal culture of Penicillium corylophilum and Aspergillus niger after 4 days of treatment. The results showed that about 24.9 g kg-1 dry sludge cake (DSC) was produced with enrichment of fungal biomass protein in fermenter while 20.1 g kg-1 in shake flask after 4 days of fungal treatment. The effective biodegradation of STP sludge was recorded in both fermenter and shake flask experiment compared to control (uninnoculated sample). The results presented in this study revealed that the overall performance of fermenter in terms of sludge cake (biosolids) accumulation and biodegradation of STP sludge was higher than the shake flask

Enhanced settleability and dewaterability of fungal treated domestic wastewater sludge by liquid state bioconversion process

A study was conducted to evaluate the settleability and dewaterability of fungal treated and untreated sludge using liquid state bioconversion process. The fungal mixed culture of Aspergillus niger and Penicillium corylophilum was used for fungal pretreatment of wastewater sludge. The fungal strains immobilized/entrapped on sludge particles with the formation of pellets and enhanced the separation process. The results presented in this study showed that the sludge particles (pellets) size of 2–5mm of diameter were formed with the microbial treatment of sludge after 2 days of fermentation that contained maximum 33.7% of total particles with 3–3.5mm of diameter. The settling rate (measured as total suspended solids (TSS) concentration, 130 mg/l) was faster in treated sludge than untreated sludge (TSS concentration, 440 mg/l) after 1 min of settling time. In 1 min of settling operation, 86.45% of TSS was settled in treated sludge while 4.35% of TSS settled in raw sludge. Lower turbidity was observed in treated sludge as compared to untreated sludge. The results to specific resistance to filtration (SRF) revealed that the fungal inoculumhad significant potentiality to reduce SRF by 99.8% and 98.7% for 1% w/w and 4% w/w of TSS sludge, respectively. The optimum fermentation period recorded was 3 days for 1% w/w sludge and 6 days for 4% w/w sludge, respectively, for dewaterability test

Effect of agitation and aeration on bioconversion of domestic wastewater sludge in a batch fermenter

Effects of agitation and aeration rate on microbial treatment of domestic wastewater sludge were investigated in a batch fermenter using mixed culture of Penicillium corylophilum and Aspergillus niger. It was found that liquid state bioconversion (LSB) of wastewater sludge was highly influenced by the effects of agitation and aeration. The maximum production of sludge cake and reduction of organic substances in treated sludge were recorded at 150–200 rpm of agitation speed and 0.5 vvm of aeration rate after 72 h of treatment. No effective results were observed at higher rate of agitation (300 rpm) and aeration (1.5 vvm) as compared to optimum values. The results showed that the minimum level of air saturation (pO2) was adequate to maintain the bioconversion process

Study of biological parameters during composting of sewage sludge

The development of appropriate strategies for the treatment and disposal of sewage sludge is a major problem for all countries throughout the World. Sludge treatment and disposal not only represents about half of the total costs of municipal wastewater collection, but it is also strongly regulated, more so than almost and other forms of waste. The sewage sludge used in this study was collected from Taman Sri Nanding and Taman Koperasi Indah Water Konsortium treatment plants Malaysia. The sludges had a higher moisture content around 80% to 82% and a low C/N ratio of 7 to 8.5. Both sludges had more or less similar characteristics. However pH of sludge from Taman Sri Nanding was lower than that of Taman Koperasi. Sawdust had a low moisture content of 10-20% and a high C/N ratio ranging from 166.6 to 285. Hence sawdust was homogenized with the sludge to increase the C/N ratio of the sludge, which inoculated with a mixture of P.chrysosporium and Trichoderima harzinum. This also reduced the moisture content to the optimal level for composting. In a medium scale horizontal drum bioreactor occurred for 21 days and one month curing, the biological parameters were monitored to evaluate the effect of sawdust on the composting process

Optimization of liquid state bioconversion process for microbial treatment of domestic wastewater sludge

The evaluation of cheap carbon sources (co-substrate) and process conditions for microbial treatment of domestic wastewater sludge (DWS) was investigated using a liquid state bioconversion (LSB) laboratory scale process. Six cheap carbon sources were used: wheat flour (WF), rice flour (RF), corn flour (CF), sago starch (SS), cassava starch (CS), and commercial sugar (S). Process conditions such as co-substrate(s) concentration, temperature, initial pH, and inoculum size were optimized in terms of dry filter cake (DFC) production, removal of total suspended solids (TSS),turbidity (optical density against distilled water, 660 nm), and chemical oxygen demand (COD) in supernatant. The results obtained indicated that sludge containing wheat flour as a carbon source was a better co-substrate for microbial growth,with significant utilization for minimizing the dissolved and suspended materials in sludge. The optimized parameters for fungal treatment of DWS obtained were 1.5–2% (w/w) of WF concentration, temperature of 33–35◦C, initial pH of 4.5–5.5, and inoculum size of 2–3% v/w. Effective results for optimum values were recoded at 4 d of microbial treatment

Evaluation of solid-state bioconversion of domestic wastewater sludge as a promising environmental-friendly disposal technique

Natural and environmental-friendly disposal of wastewater sludge is a great concern. Recently, biological treatment has played prominent roles in bioremediation of complex hydrocarbon- rich contaminants. Composting is quite an old biological-based process that is being practiced but it could not create a great impact in the minds of concerned researchers. The present study was conducted to evaluate the feasibility of the solid-state bioconversion (SSB) processes in the biodegradation of wastewater sludge by exploiting this promising technique to rejuvenate the conventional process. The Indah Water Konsortium (IWK) domestic wastewater treatment plant (DWTP) sludge was considered for evaluation of SSB by monitoring the microbial growth and its subsequent roles in biodegradation under two conditions:(i) flask (F) and (ii) composting bin (CB) cultures. Sterile and semi-sterile environments were allowed in the F and the CB, respectively, using two mixed fungal cultures, Trichoderma harzianum with Phanerochaete chrysosporium 2094 (T/P) and T. harzianum with Mucor hiemalis (T/M) and two bulking materials, sawdust (SD) and rice straw (RS). The significant growth and multiplication of both the mixed fungal cultures were reflected in soluble protein, glucosamine and color intensity measurement of the water extract. The color intensity and pH of the water extract significantly increased and supported the higher growth of microbes and bioconversion. The most encouraging results of microbial growth and subsequent bioconversion were exhibited in the RS than the SD. A comparatively higher decrease of organic matter (OM) % and C/N ratio were attained in the CB than the F, which implied a higher bioconversion. But the measurement of soluble protein, glucosamine and color intensity exhibited higher values in the F than the CB. The final pH drop was higher in the CB than the F, which implied that a higher nitrification occurred in the CB associated with a higher release of H+ ions. Both the mixed cultures performed almost equal roles in all cases except the changes in moisture content

Biosolids accumulation and biodegradation of domestic wastewater treatment plant sludge by developed liquid state bioconversion process using a batch fermenter

The biosolids accumulation and biodegradation of domestic wastewater treatment plant (DWTP) sludge by filamentous fungi have been investigated in a batch fermenter. The filamentous fungi Aspergillus niger and Penicillium corylophilum isolated from wastewater and DWTP sludge was used to evaluate the treatment performance. The optimized mixed inoculum (A. niger and P. corylophilum) and developed process conditions (co-substrate and its concentration, temperature, initial pH, inoculum size, and aeration and agitaion rate) were incorporated to accelerate the DWTP sludge treatment process. The results showed that microbial treatment of higher strength of DWTP sludge (4% w/w of TSS) was highly influenced by the liquid state bioconversion (LSB) process. In developed bioconversion processes, 93.8 g/kg of biosolids was enriched with fungal biomass protein of 30 g/kg. Enrichment of nutrients such as nitrogen (N), phosphorous (P), potassium (K) in biosolids was recorded in 6.2% (w/w), 3.1% (w/w) and 0.15% (w/w) from its initial values of 4.8% (w/w), 2.0% (w/w) and 0.08% (w/w) respectively after 10 days of fungal treatment. The biodegradation results revealed that 98.8% of TSS, 98.2% of TDS, 97.3% of turbidity, 80.2% of soluble protein, 98.8% of reducing sugar and 92.7% of COD in treated DWTP sludge supernatant were removed after 8 days of microbial treatment. The specific resistance to filtration (SRF) in treated sludge (1.4�1012 m/kg) was decreased tremendously by the microbial treatment of DWTP sludge after 6 days of fermentation compared to untreated sample (85�1012 m/kg)

Optimization of single and mixed cultures for solid state fermentation of municipal sewage sludge

Trichoderma harzianum (Th), Phanerochaete chrysosporium ATCC 24725 (Pc) and Mucor hiemalis (Mh) isolated from three sources: wastewater; sewage sludge; and sludge cake were selected for use as compatible/incompatible single and mixed cultures in the treatment of munici- pal sewage sludge. Five experiments were carried out using (Pc), (Th), a mixture of (Pc/Th), (Mh) and a mixture of (Pc/Mh), in addition to a control where no micro-organism was used. The experiments were used to evaluate their potential performance as compatible/incompatible single and mixed cultures for the treatment of municipal wastewater sewage sludge from treatment plants using solid state fermentation technique (SSF). The results showed that the best micro- organism for composting was found to be (Th) and a mixture of (Pc/Th), while (Pc/Mh) was incompatible culture. The C/N ratio for Th changed from 8.46 to 17.8 at the end of the process, (Ph/Th) increased from 7.21 to 15.9, while (Pc/Mh) increased from 8.49 to 29. The pH value also affected by the fungal cultures which was also changed for (Th) from 4.29 to 6.8, for (Pc/Th) was changed from 7.27 to 6.7 and for (Pc/Mh) was changed from 6.6 to 5.3. Effective results were observed by using mixed culture after 19–21 days compared to other single treatments after 24–32 days

Bioconversion of domestic wastewater sludge by immobilized mixed culture of Penicillum Corylophilum WWZA1003 and Aspergillus Niger SCahmA103

The bioconversion of domestic wastewater sludge by immobilized mixed culture of filamentous fungi was investigated in a laboratory. The potential mixed culture of Penicillium corylophilum WWZA1003 and Aspergillus niger SCahmA103 was isolated from its local habitats (wastewater and sludge cake) and optimized on the basis of biodegradability and dewaterability of treated sludge. The observed results in this study showed that the sludge treatment was highly influenced by the effect of immobilized mixed fungi using liquid state bioconversion (LSB) process. The maximum production of dry filter cake (DFC) was enriched with fungal biomass to about 20.05 g/kg containing 23.47 g/kg of soluble protein after 4 days of fungal treatment. The reduction of COD, TSS, turbidity (optical density against distilled water, 660 nm), reducing sugar and protein in supernatant and filtration rate of treated sludge were influenced by the fungal mixed culture as compared to control (uninnoculated). After these processes, 99.4% of TSS, 98.05% of turbidity,76.2% of soluble protein, 98% of reducing sugar and 92.4% of COD in supernatant of treated sludge were removed. Filtration time was decreased tremendously by the microbial treatment after 2 days of incubation. The effect of fungal strain on pH was also studied and presented. Effective bioconversion was observed after 4 days of fungal treatment