This study investigated the removal of parabens, N,N-diethyl-m-toluamide (DEET), and phthalates by ozonation. The second-order rate constants for the reaction between selected compounds with ozone at pH 7 were of (2.2 +/-0.2) X 10(6) to (2.9 +/-0.3) X 10(6) M 1/s for parabens, (2.1+/- 0.3) to (3.9 +/-0.5) M-1/s for phthalates, and (5.2 +/-0.3) M-1/s for DEET. The rate constants for the reaction between selected compounds with hydroxyl radical ranged from (2.49 +/-0.06) x 10(9) to (8.5 +/-0.2) x 10(9) M-1/s. Ozonation of selected compounds in secondary wastewater and surface waters revealed that ozone dose of 1 and 3 mg/L yielded greater than 99% depletion of parabens and greater than 92% DEET and phthalates, respectively. In addition, parabens were found to transform almost exclusively through the reaction with ozone, while DEET and phthalates were transformed almost entirely by hydroxyl radicals (.OH).
Environmental contamination by petroleum hydrocarbons, mainly crude oil waste from refineries, is becoming prevalent worldwide. This study investigates the bioremediation of water contaminated with crude oil waste. Bacillus salamalaya 139SI, a bacterium isolated from a private farm soil in the Kuala Selangor in Malaysia, was found to be a potential degrader of crude oil waste. When a microbial population of 108 CFU ml-1 was used, the 139SI strain degraded 79% and 88% of the total petroleum hydrocarbons after 42 days of incubation in mineral salt media containing 2% and 1% of crude oil waste, respectively, under optimum conditions. In the uninoculated medium containing 1% crude oil waste, 6% was degraded. Relative to the control, the degradation was significantly greater when a bacteria count of 99 × 108 CFU ml-1 was added to the treatments polluted with 1% oil. Thus, this isolated strain is useful for enhancing the biotreatment of oil in wastewater.
Polyhydroxyalkanoates (PHAs) has been paid great attention because of its useful thermoplastic properties and complete degradation in various natural environments. But, at industrial level, the successful commercialization of PHAs is limited by the high production cost due to the expensive carbon source and recovery processes. Pseudomonas mendocina PSU cultured for 72 h in mineral salts medium (MSM) containing 2% (v/v) biodiesel liquid waste (BLW) produced 79.7 wt% poly(3-hydroxybutyrate) (PHB) at 72 h. In addition, this strain produced 43.6 wt% poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 8.6 HV mol% at 60 h when added with 0.3% sodium propionate. The synthesized intracellular PHA granules were recovered and purified by the recently reported biological method using mealworms. The weight average molecular weight (Mw ) and number average molecular weight (Mn ) of the biologically extracted PHA were higher than that from the chloroform extraction with comparable melting temperature (Tm ) and high purity. This study has successfully established a low-cost process to synthesize PHAs from BLW and subsequently confirmed the ability of mealworms to extract PHAs from various kinds of bacterial cells.
Reserve lipids of microalgae are promising for biodiesel production. However, economically feasible and sustainable energy production from microalgae requires optimization of cultivation conditions for both biomass yield and lipid production of microalgae. Biomass yield and lipid production in microalgae are a contradictory problem because required conditions for both targets are different. Simultaneously, the mass cultivation of microalgae for biofuel production also depends extremely on the performance of the microalgae strains used. In this study a green unicellular microalgae Chlorella sorokiniana (DS6) isolated from the holding tanks of farm wastewater treatment plant using multi-step screening and acclimation procedures was found high-lipid producing facultative heterotrophic microalgae strain capable of growing on dairy farm effluent (DFE) for biodiesel feedstock and wastewater treatment. Morphological features and the phylogenetic analysis for the 18S rRNA identified the isolated strains. A novel three stage cultivation process of facultative strain of C. sorokiniana was examined for lipid production.
Steroid estrogens, such as estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethinylestradiol (EE2), are natural and synthetic hormones released into the environment through incomplete sewage discharge. This review focuses on the sources of steroid estrogens in wastewater treatment plants (WWTPs). The mechanisms and fate of steroid estrogens throughout the entire wastewater treatment system are also discussed, and relevant information on regulatory aspects is given. Municipal, pharmaceutical industry, and hospitals are the main sources of steroid estrogens that enter WWTPs. A typical WWTP comprises primary, secondary, and tertiary treatment units. Sorption and biodegradation are the main mechanisms for removal of steroid estrogens from WWTPs. The fate of steroid estrogens in WWTPs depends on the types of wastewater treatment systems. Steroid estrogens in the primary treatment unit are removed by sorption onto primary sludge, followed by sorption onto micro-flocs and biodegradation by microbes in the secondary treatment unit. Tertiary treatment employs nitrification, chlorination, or UV disinfection to improve the quality of the secondary effluent. Activated sludge treatment systems for steroid estrogens exhibit a removal efficiency of up to 100%, which is higher than that of the trickling filter treatment system (up to 75%). Moreover, the removal efficiency of advance treatment systems exceeds 90%. Regulatory aspects related to steroid estrogens are established, especially in the European Union. Japan is the only Asian country that implements a screening program and is actively involved in endocrine disruptor testing and assessment. This review improves our understanding of steroid estrogens in WWTPs, proposes main areas to be improved, and provides current knowledge on steroid estrogens in WWTPs for sustainable development.
The conventional treatment process of palm oil mill effluent (POME) produces a highly colored effluent. Colored compounds in POME cause reduction in photosynthetic activities, produce carcinogenic by-products in drinking water, chelate with metal ions, and are toxic to aquatic biota. Thus, failure of conventional treatment methods to decolorize POME has become an important problem to be addressed as color has emerged as a critical water quality parameter for many countries such as Malaysia. Aspergillus fumigatus isolated from POME sludge was successfully grown in POME supplemented with glucose. Statistical optimization studies were conducted to evaluate the effects of the types and concentrations of carbon and nitrogen sources, pH, temperature, and size of the inoculum. Characterization of the fungus was performed using scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and Brunauer, Emmet, and Teller surface area analysis. Optimum conditions using response surface methods at pH 5.7, 35 °C, and 0.57 % w/v glucose with 2.5 % v/v inoculum size resulted in a successful removal of 71 % of the color (initial ADMI of 3,260); chemical oxygen demand, 71 %; ammoniacal nitrogen, 35 %; total polyphenolic compounds, 50 %; and lignin, 54 % after 5 days of treatment. The decolorization process was contributed mainly by biosorption involving pseudo-first-order kinetics. FTIR analysis revealed that the presence of hydroxyl, C-H alkane, amide carbonyl, nitro, and amine groups could combine intensively with the colored compounds in POME. This is the first reported work on the application of A. fumigatus for the decolorization of POME. The present investigation suggested that growing cultures of A. fumigatus has potential applications for the decolorization of POME through the biosorption and biodegradation processes.
In this present study, adsorptive membranes for Cr(VI) ion removal were prepared by blending polyethersulfone (PES) with hydrous ferric oxide (HFO) nanoparticles (NPs). The effects of HFO NPs to PES weight ratio (0-1.5) on the physicochemical properties of the resultant HFO/PES adsorptive membranes were investigated with respect to the surface chemistry and roughness as well as structural morphologies using different analytical instruments. The adsorptive performance of the HFO NPs/PES membranes was studied via batch adsorption experiments under various conditions by varying solution pH, initial concentration of Cr(VI), and contact time. The results showed that the membrane made of HFO/PES at a weight ratio of 1.0 exhibited the highest adsorption capacity which is 13.5 mg/g. Isotherm and kinetic studies revealed that the mechanism is best fitted to the Langmuir model and pseudo-second-order model. For filtration of Cr(VI), the best promising membranes showed improved water flux (629.3 L/m2 h) with Cr(VI) ion removal of 75%. More importantly, the newly developed membrane maintained the Cr(VI) concentration below the maximum contamination level (MCL) for up to 9 h.