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

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

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

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 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

Evaluation of fungal potentiality for bioconversion of domestic wastewater sludge

This study was undertaken to screen the filamentous fungi isolated from its relevant habitats (wastewater, sewage sludge and sludge cake) for the bioconversion of domestic wastewater sludge. A total of 35 fungal strains were tested against wastewater sludge (total suspended solids, TSS 1%-5% w/w) to evaluate its potentiality for enhancing the biodegradability and dewaterability using liquid state bioconversion (LSB) process. The strains were divided into five groups i.e. Penicillium, Aspergillus, Trichoderma, Basidiomycete and Miscellaneous, respectively. The strains WWZP1003, SCahmA103, SCahmT105 and PC-9 among their respective groups of Penicillium,Aspergillus, Trichoderma and Basidiomycete played potential roles in terms of separation (formation of pellets/flocs/filaments), biodegradation (removal of COD) and filtration (filterability) of treated domestic wastewater sludge. The Miscellaneous group was not considered due to its unsatisfactory results as compared to the other groups. The pH value was also influenced by the microbial treatment during fermentation process. The filterability of treated sludge was improved by fungal treatment, and lowest filtration time was recorded for the strain WWZP1003 and SCahmA103 of Penicillium and Aspergillus groups respectively compared with other strains

Compost produced by solid state bioconversion of biosolids: a potential resource for plant growth and environmental friendly disposa

Compost produced by solid-state bioconversion of the Indah Water Konsortium domestic wastewater treatment plant’s sludge/biosolids significantly influenced the plant growth and development of corn (Zea mays). The solid-state bioconversion refers to the control growth of microorganisms, generally on the surface of water-insoluble substances for biodegradation of biopolymers and bioremediation of chemical compounds. Compost of biosolids with rice straw significantly increased plant height, shoot, and root dry weight. Moreover, it promoted 100.51% dry matter production compared to control. But the dry matter was recorded 46.80% only in urea (þN) application. The highest vegetative growth and delayed drying of basal leaves were attained using 1/2 of compost with 1/2 amount of urea, of the optimal dose of nitrogen (N) requirement for corn production. The recorded heavy metals concentration in plant tissues was quite low. Most of the heavy metals in composts of biosolids were on average 30 times lower compared to the standard limit of municipal solid waste in the United States. The compost of biosolids with rice straw provided superior performance in corn growth compared to the compost of biosolids with sawdust. Both evaluated composts produced by solid-state bioconversion process were nonhazardous and did not contribute any detrimental effect or symptoms on corn growth and development. Simultaneously, it would behave as a potential sustainable environmentally friendly route of biosolids management and disposal as value added organic fertilizer for agronomic/horticultural use

Preparation of environmental friendly plastic brick from high-density polyethylene waste

Plastic wastes are growing fast and affecting the environment negatively. Thus, finding different methods of disposing of is becoming a major concern. This research aimed to minimize the plastic by recycling it into construction materials. For this, grinding high-density polyethylene (HDPE) was mixed with cement at different percentages to produce plastic bricks. The compressive strength, density, and water absorption capacity were investigated. The compressive strength was found within the recommended value (2000 psi) up to 35% mixture of HDPE. The addition of HDPE with cement decreased the density, increased the ductility, and improved the workability which led to producing lightweight materials