Solid State Bioconversion of Domestic Wastewater Treatment Plant Sludge into Compost by Screened Filamentous Fungi

Similar to other countries, Malaysia is facing problems of safe and environmental friendly disposal of domestic wastewater treatment plant (DWTP) sludge. None of the conventional disposal techniques is recognized as safe and environmental friendly. Solid state bioconversion (SSB) is emerging as a natural promising environmental friendly process. This microbial-based technique of organic wastes bioremediation is gaining greater public acceptance. This study has exploited the SSB technique to rejuvenate the compo sting process as a remedy for safe disposal and reuse of the Indah Water Konsortium (lWK) DWPT sludge. In this study isolation, screening and selection of compatible mixed fungal culture from relevant sources were followed by optimization of the SSB process. The SSB of IWK DWTP sludge into compost was examined and the compost was tested for crop growth. Six fungal strains Phanerochaete chrysosporium 2094, RW-PI 512, Trichoderma harzianums, T. harzianumc, Aspergillus versicolor and Mucor hiemalis were identified as sludge acclimatized and non-phytopathogenic among 33 members. The T. harzianums with P. chrysosporium 2094 (TIP), and T. harzianums with M. hiemalis (TIM) were selected as the best compatible mixed fungal cultures. Four factors were optimized based on superior production of biomass, total organic carbon (TOC) and soluble protein (SP) for both mixed cultures of SSB of the IWK DWTP sludge. These were CIN ratio 30:1, wheat flour (WF) as a cheap carbon source, pH 4.5 to 5 . 5 and rice straw (RS) as a bulking material. Higher microbial growth was obtained in RS compared to sawdust (SD) in SSB of the IWK DWTP sludge based on measurement of optical density, soluble protein and glucosamine. Significantly the lowest CIN ratio of 12.14 for TIP and 12.58 for TIM were achieved using RS in composting bin at 75 days. The lowest germination index of 33.43% for TIP and 39.4% for TIM were attained at 30 days. Then it rose to around 90% at 60 days using RS in compo sting bin. The suitable electrical conductivity (EC dS/m) values of 0.33 for TIP and 0.35 for TIM in SD, 1.41 for TIP and 1.49 for TIM were attained in RS at 75 days. The above facts support the production of stabilized composts. Comparatively, superior composts were produced by TIP around 50-60 days of SSB. Compost could provide 50% N requirement of optimal dose of com production. Around 65 to 100% higher dry matter production was attained by 50% compost plus 50% N treatment compared to control. Heavy metals uptake were low; whereby the composts of the IWK DWTP sludge contained average 30 times lower than the USA standard limit. The SSB is potentially capable of natural friendly biodegradation of the IWK DWTP sludge into compost with significant reduction of moisture and volume, which have an excellent use for organic farming. It will open a new route of final safe disposal of the IWK DWTP sludge

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 × 1012 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

Potential for enhancement of root growth and nodulation of soybean co-inoculated with Azospirillum and Bradyrhizobium in laboratory systems

The potential enhancement of root growth and nodulation in vegetable soybean (AGS190) was studied with application of Azospirillum brasilense (Sp7) and A. lipoferum (CCM3863) co-inoculated with two Bradyrhizobium japonicum strains (TAL102 and UPMR48). Significant root growth stimulation and nodulation were observed in Azospirillum as well as during its co-inoculation with Bradyrhizobium. Nodule formation is linked with the initiation of new roots; nodules were almost absent even in Bradyrhizobium inoculated plant due to the absence of new roots development in clipped rooted seedlings. Total root length, root number, specific root length, root dry matter, root hair development and shoot dry matter were significantly increased by Azospirillum alone and its co-inoculum. Co-inoculated plants significantly influenced the number of nodules and its fresh weight. A. brasilense seemed to perform better in root growth and nodule development compared to A. lipoferum

Operational characteristics and determination of resistance for effective powering and propulsion of fishing boats of lower Perak River of Malaysia

The case study of a resistance and propulsion characteristics of a typical small traditional fishing boats of lower Perak River of Malaysia is reported in this paper. The aim of this study is to provide a better or more efficient method of determining the effective powering and propulsion of fishing boats. For the estimation of propeller characteristics, the propeller "SK" - series diagrams were used. The results of the calculations show that the efficiency of the conversion process of the engine power into the effective thrust can be improved by proper selection of the engine, propeller and its parameters. The power requirement of the engine according to the calculation was found to be 6.4 kW and 7.5 kW for the propeller speeds of 1000 rpm and 300 rpm respectively for Vs = 8.5 knots. Thus the power-displacement ratio varies from 1.28 kW/ton depending on the propeller speed. Efforts have been made for proper powering and propulsion of the traditional fishing boats in order to minimize the fuel cost

Optimization of process parameters for pilot-scale liquid-state bioconversion of sewage sludge by mixed fungal inoculation

Liquid-state bioconversion (LSB) technique has great potential for application in bioremediation of sewage sludge. The purpose of this study is to determine the optimum level of LSB process of sewage sludge treatment by mixed fungal (Aspergillus niger and Penicillium corylophilum) inoculation in a pilot-scale bioreactor. The optimization of process factors was investigated using response surface methodology based on Box–Behnken design considering hydraulic retention time (HRT) and substrate influent concentration (S0) on nine responses for optimizing and fitted to the regression model. The optimum region was successfully depicted by optimized conditions, which was identified as the best fit for convenient multiple responses. The results from process verification were in close agreement with those obtained through predictions. Considering five runs of different conditions of HRT (low, medium and high 3.62, 6.13 and 8.27 days, respectively) with the range of S0 value (the highest 12.56 and the lowest 7.85 g L−1), it was monitored as the lower HRT was considered as the best option because it required minimum days of treatment than the others with influent concentration around 10 g L−1. Therefore, optimum process factors of 3.62 days for HRT and 10.12 g L−1 for S0 were identified as the best fit for LSB process and its performance was deviated by less than 5% in most of the cases compared to the predicted values. The recorded optimized results address a dynamic development in commercial-scale biological treatment of wastewater for safe and environment-friendly disposal in near future

Ultrasound-assisted extraction of natural dye from Swietenia mahagoni and its application on silk fabric

The current study deals with the extraction of natural dyes from the flower of the Sweitenia mahagoni plant by ultrasound-assisted extraction method using ethanol as solvent. Box-Behnken design has been employed to optimize and investigate the effect of three independent variables (sample-solvent ratio, sonication time and extraction temperature) on the natural dye yield. The results reveal that the experimental data are fitted to a second-order polynomial equation using multiple regression analysis with high coefficient of determination value (R2> 0.98, Adj. R² >0.96 & Pred. R² >0.81). Optimal extraction conditions for the dyes yield are: sample-solvent ratio 1/20 g/mL, sonication time 30 min and extraction temperature 50°C. Under these conditions, the highest dyes yield is predicted to be 0.855%. FTIR spectroscopy has been used to identify the major chemical group in the extracted dye. Further, dyeing of silk fabric has been carried out by an exhausted dyeing method and the dyeing property and fastness properties of the dyed samples are also assessed

Ultrasound-assisted extraction of natural dye from Swietenia mahagoni and its application on silk fabric

69-77The current study deals with the extraction of natural dyes from the flower of the Sweitenia mahagoni plant by ultrasound-assisted extraction method using ethanol as solvent. Box-Behnken design has been employed to optimize and investigate the effect of three independent variables (sample-solvent ratio, sonication time and extraction temperature) on the natural dye yield. The results reveal that the experimental data are fitted to a second-order polynomial equation using multiple regression analysis with high coefficient of determination value (R2> 0.98, Adj. R² >0.96 & Pred. R² >0.81). Optimal extraction conditions for the dyes yield are: sample-solvent ratio 1/20 g/mL, sonication time 30 min and extraction temperature 50°C. Under these conditions, the highest dyes yield is predicted to be 0.855%. FTIR spectroscopy has been used to identify the major chemical group in the extracted dye. Further, dyeing of silk fabric has been carried out by an exhausted dyeing method and the dyeing property and fastness properties of the dyed samples are also assessed

Risk of Nosocomial Transmission of Nipah Virus in a Bangladesh Hospital

We conducted a seroprevalence study and exposure survey of healthcare workers to assess the risk of nosocomial transmission of Nipah virus during an outbreak in Bangladesh in 2004. No evidence of recent Nipah virus infection was detected despite substantial exposures and minimal use of personal protective equipmen

Person-to-Person Transmission of Nipah Virus in a Bangladeshi Community

Transmission of this virus highlights the need for infection control strategies for resource-poor settings

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)