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Statistical optimization of process conditions for cellulase production by liquid state bioconversion of domestic wastewater sludge

Alam MZ, Muyibi SA, Wahid R

Bioresour Technol, 2008 Jul;99(11):4709-16.
PMID: 17981027

A two-level fractional factorial design (FFD) was used to determine the effects of six factors, i.e. substrate (domestic wastewater sludge - DWS) and co-substrate concentration (wheat flour - WF), temperature, initial pH, inoculum size and agitation rate on the production of cellulase enzyme by Trichoderma harzianum in liquid state bioconversion. On statistical analysis of the results from the experimental studies, optimum process conditions were found to be temperature 32.5 degrees C, substrate concentration (DWS) 0.75% (w/w), co-substrate (WF) concentration 2% (w/w), initial pH 5, inoculum size 2% (v/w) and agitation 175 rpm. Analysis of variance (ANOVA) showed a high coefficient of determination (R2) of 0.975. Cellulase activity reached 10.2 FPU/ml at day 3 during the fermentation process which indicated about 1.5-fold increase in production compared to the cellulase activity obtained from the results of design of experiment (6.9 FPU/ml). Biodegradation of DWS was also evaluated to verify the efficiency of the bioconversion process as a waste management method.
Parents' linguistic strategies in interaction with their children with history of cleft lip and/or palate

Saad MA, Jan JM, Wahid R

Int J Lang Commun Disord, 2021 Jul 11.
PMID: 34250713 DOI: 10.1111/1460-6984.12646

BACKGROUND: Cleft lip and/or palate (CL/P) presents a rather complex challenge that requires understanding beyond biological or clinical perspective. Even though inaccuracies in speech articulation are the common consequences of CL/P, individuals with repaired CL/P are likely to experience other language-associated issues. Studies on social interaction have generally reported the children to be passive interlocutors, despite having their surgical treatment at the early stages of life.
AIMS: This study aims to describe the linguistic strategies that parents employ when interacting with their repaired CL/P child. How parents allocate the next turn of speaking to their repaired CL/P child will be specifically examined.
METHODS & PROCEDURES: Three parent-child pairs with each child having repaired CL/P were selected to participate in the study. Guided by the principles of Conversation Analysis, their everyday interactions in their homes were video-recorded and transcribed according to the Jefferson System of Transcription Notation (2004). The transcriptions were subsequently analysed in order to highlight the linguistic strategies.
OUTCOMES & RESULTS: Three main linguistic strategies are identified in the parents' turns when they allocate the next turn of speaking to their repaired CL/P child. Specifically, parents' turns are constructed through interrogative sentences in addition to using emphasis words and repeated elicitation of responses from their child.
CONCLUSION & IMPLICATIONS: Parents' linguistic strategies are found to be restrictive as they limit children's active participation. Consequently, the interaction becomes asynchronous rather than synchronous, which could otherwise benefit children's language development. Findings provide information on how parents can be supported in order to foster a positive growth of the children's language development through everyday interactions.
WHAT THIS PAPER ADDS: What is already known on the subject Even after repair surgery, children with CL/P may experience poor language performance that is not limited to inaccuracies in speech articulation. Studies within the area of pragmatics have consistently shown the CL/P children to be passive interlocutors. What this paper adds to existing knowledge This study describes the linguistic strategies employed by parents when they allocate the next turn of speaking to their repaired CL/P child. Parents are found to employ three main strategies: framing the turn into an interrogative sentence, deploying emphasis words and repeatedly eliciting responses. The findings suggest that such strategies limit the interactions, making them asynchronous and potentially unconducive to the positive growth of the child's language development. What are the potential or actual clinical implications of this work? In addition to providing speech treatment to children affected with CL/P, parents, especially those belonging to collectivist groups that are sympathetic to authoritarian parenting styles, can also be informed or trained on other ways to communicate with such individuals.
Fulltext Study on the drying performance and milling quality of dried paddy using inclined bed dryers in two different paddy mills located in MADA and IADA KETARA

Sahari, Y., Abdul Wahid, R., Mhd Adnan, A. S., Sairi, M., Hosni, H., Engku Abdullah, E. H., et al.

International Food Research Journal, 2018;25(6):2572-2578.
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The drying performance of industrial inclined bed dryer (IBD) and the milling quality of dried paddy was evaluated and compared in two main granary areas of Muda Agricultural Development Authority (MADA) and Integrated Agricultural Development Areas (IADA KETARA). A mix of MARDI’s paddy variety (MR 220 CL2 and MR 219) was used and the study on both granary area of MADA and IADA KETARA were carried out in local paddy mills located at Yan, Kedah and Besut, Terengganu respectively. The results indicated that the average drying rate in MADA was 119.93 kg water removed/hr whereas only 73.67 kg water removed/hr was recorded in IADA KETARA. Therefore, normalized water removal value of paddy mill in MADA was found higher than paddy mill in IADA KETARA. In terms of milling quality, average percentage of head rice yield of paddy mill in MADA and IADA KETARA was 76.89% and 73.87% respectively. The milling quality analysis of rice resulted from ANOVA found that there was no significant difference in the HRY and total broken between IBDs in both locations.
Fulltext Mesophilic versus thermophilic anaerobic digestion of cattle manure: methane productivity and microbial ecology

Moset V, Poulsen M, Wahid R, Højberg O, Møller HB

Microb Biotechnol, 2015 Sep;8(5):787-800.
PMID: 25737010 DOI: 10.1111/1751-7915.12271

In this study, productivity and physicochemical and microbiological (454 sequencing) parameters, as well as environmental criteria, were investigated in anaerobic reactors to contribute to the ongoing debate about the optimal temperature range for treating animal manure, and expand the general knowledge on the relation between microbiological and physicochemical process indicators. For this purpose, two reactor sizes were used (10 m(3) and 16 l), in which two temperature conditions (35°C and 50°C) were tested. In addition, the effect of the hydraulic retention time was evaluated (16 versus 20 days). Thermophilic anaerobic digestion showed higher organic matter degradation (especially fiber), higher pH and higher methane (CH₄) yield, as well as better percentage of ultimate CH₄ yield retrieved and lower residual CH₄ emission, when compared with mesophilic conditions. In addition, lower microbial diversity was found in the thermophilic reactors, especially for Bacteria, where a clear intensification towards Clostridia class members was evident. Independent of temperature, some similarities were found in digestates when comparing with animal manure, including low volatile fatty acids concentrations and a high fraction of Euryarchaeota in the total microbial community, in which members of Methanosarcinales dominated for both temperature conditions; these indicators could be considered a sign of process stability.
Activated carbons derived from oil palm empty-fruit bunches: application to environmental problems

Alam MZ, Muyibi SA, Mansor MF, Wahid R

J Environ Sci (China), 2007;19(1):103-8.
PMID: 17913162

Activated carbons derived from oil palm empty fruit bunches (EFB) were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process. Two types of activation namely; thermal activation at 300, 500 and 800 degrees C and physical activation at 150 degrees C (boiling treatment) were used for the production of the activated carbons. A control (untreated EFB) was used to compare the adsorption capacity of the activated carbons produced from these processes. The results indicated that the activated carbon derived at the temperature of 800 degrees C showed maximum absorption capacity in the aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon at 800 degrees C. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data fitted better with the Freundlich adsorption isotherm compared to the Langmuir. Kinetic studies of phenol adsorption onto activated carbons were also studied to evaluate the adsorption rate. The estimated cost for production of activated carbon from EFB was shown in lower price (USD 0.50/kg of activated carbon) compared the activated carbon from other sources and processes.
Removal of phenol by activated carbons prepared from palm oil mill effluent sludge

Alam MZ, Muyibi SA, Mansor MF, Wahid R

J Environ Sci (China), 2006;18(3):446-52.
PMID: 17294638

The study was attempted to produce activated carbons from palm oil mill effluent (POME) sludge. The adsorption capacity of the activated carbons produced was evaluated in aqueous solution of phenol. Two types of activation were followed, namely, thermal activation at 300, 500 and 800 degrees C, and physical activation at 15 degrees C (boiling treatment). A control (raw POME sludge) was used to compare the adsorption capacity of the activated carbons produced. The results indicated that the activation temperature of 800 degrees C showed maximum absorption capacity by the activated carbon (POME 800) in aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon of POME 800. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data were fitted by the Langmuir and Freundlich adsorption isotherms. The adsorption of phenol onto the activated carbon POME 800 was studied in terms of pseudo- first and second order kinetics to predict the rate constant and equilibrium capacity with the effect of initial phenol concentrations. The rate of adsorption was found to be better correlation for the pseudo-second order kinetics compared to the first order kinetics.
Biogas potential from forbs and grass-clover mixture with the application of near infrared spectroscopy

Wahid R, Ward AJ, Møller HB, Søegaard K, Eriksen J

Bioresour Technol, 2015 Dec;198:124-32.
PMID: 26386414 DOI: 10.1016/j.biortech.2015.08.154

This study investigated the potentials of forbs; caraway, chicory, red clover and ribwort plantain as substrates for biogas production. One-, two- and four-cut systems were implemented and the influence on dry matter yields, chemical compositions and methane yields were examined. The two- and four-cut systems resulted in higher dry matter yields (kg [total solid, TS] ha(-1)) compared to the one-cut system. The effect of plant compositions on biogas potentials was not evident. Cumulative methane yields (LCH4kg(-1) [volatile solid, VS]) were varied from 279 to 321 (chicory), 279 to 323 (caraway), 273 to 296 (ribwort plantain), 263 to 328 (red clover) and 320 to 352 (grass-clover mixture), respectively. Methane yield was modelled by modified Gompertz equation for comparison of methane production rate. Near infrared spectroscopy showed potential as a tool for biogas and chemical composition prediction. The best prediction models were obtained for methane yield at 29 days (99 samples), cellulose, acid detergent fibre, neutral detergent fibre and crude protein, (R(2)>0.9).
Improvement of wheat straw anaerobic digestion through alkali pre-treatment: Carbohydrates bioavailability evaluation and economic feasibility

Romero-Güiza MS, Wahid R, Hernández V, Møller H, Fernández B

Sci Total Environ, 2017 Oct 01;595:651-659.
PMID: 28402918 DOI: 10.1016/j.scitotenv.2017.04.006

Lignocellulosic biomasses such as wheat straw are widely used as a feedstock for biogas production. However, these biomasses are mainly composed of a compact fibre structure and therefore, it is recommended to treat them prior to its usage for biogas production in order to improve their bioavailability. The aim of this work is to evaluate, in terms of performance stability, methane yield and economic feasibility, two different scenarios: a mesophilic codigestion of wheat straw and animal manure with or without a low-energy demand alkaline pre-treatment (0.08gKOHgTS-1of wheat straw, for 24h and at 25°C). Besides this, said pre-treatment was also analysed based on the improvement of the bioavailable carbohydrate content in the untreated versus the pre-treated wheat straw. The results pointed out that pre-treated wheat straw prompted a more stable performance (in terms of pH and alkalinity) and an improved methane yield (128% increment) of the mesophilic codigestion process, in comparison to the "untreated" scenario. The pre-treatment increased the content of cellulose, hemicellulose and other compounds (waxes, pectin, oil, etc.) in the liquid fraction, from 5% to 60%, from 11.5% to 39.1% TS and from 57% to 79% of the TS in the liquid fraction for the untreated and pre-treated wheat straws, respectively. Finally, the pre-treated scenario gained an energy surplus of a factor 13.5 and achieved a positive net benefit of 90.4€tVS-WS-1d-1, being a favourable case for an eventual scale-up of the combined process.
Fulltext Evaluating Fertilizer-Drawn Forward Osmosis Performance in Treating Anaerobic Palm Oil Mill Effluent

Abdul Wahid R, Ang WL, Mohammad AW, Johnson DJ, Hilal N

Membranes (Basel), 2021 Jul 28;11(8).
PMID: 34436329 DOI: 10.3390/membranes11080566

Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill effluent (An-POME). The process parameters affecting FO were studied and optimized, which were then applied to fertilizer selection based on FO performance and fouling propensity. Six commonly used fertilizers were screened and assessed in terms of pure water flux (Jw) and reverse salt flux (JS). Ammonium sulfate ((NH4)2SO4), mono-ammonium phosphate (MAP), and potassium chloride (KCl) were further evaluated with An-POME. MAP showed the best performance against An-POME, with a high average water flux, low flux decline, the highest performance ratio (PR), and highest water recovery of 5.9% for a 4-h operation. In a 24-h fouling run, the average flux decline and water recovered were 84% and 15%, respectively. Both hydraulic flushing and osmotic backwashing cleaning were able to effectively restore the water flux. The results demonstrated that FDFO using commercial fertilizers has the potential for the treatment of An-POME for water recovery. Nevertheless, further investigation is needed to address challenges such as JS and the dilution factor of DS for direct use of fertigation.