Performance of a seawater-driven forward osmosis process for pre-concentrating digested sludge centrate: Organic enrichment and membrane fouling

© 2018 The Royal Society of Chemistry. This study demonstrated the potential of seawater-driven forward osmosis for enriching organic matter in digested sludge centrate. The results indicated that the cellulose triacetate membrane offered better performance than the polyamide membrane in terms of organic materials enrichment, fouling resistance and membrane cleaning efficiency. Membrane fouling decreased the enrichment efficiency of organic matter since the deposition of suspended particulate matter on the membrane surface caused fouling and loss of organic matter from the concentrated sludge centrate. The results showed that increasing the draw solution concentration increased flux but did not aggravate membrane fouling, however, it could reduce the efficiency of physical flushing to recover the flux. Seawater showed comparable forward osmosis performance to that of analytical grade NaCl as draw solutes in terms of flux and organic enrichment. The results also showed that seawater as the draw solution resulted in more membrane fouling and lower flux recovery compared to NaCl

Large-scale exploration of neural relation classification architectures

Experimental performance on the task of relation classification has generally improved using deep neural network architectures. One major drawback of reported studies is that individual models have been evaluated on a very narrow range of datasets, raising questions about the adaptability of the architectures, while making comparisons between approaches difficult. In this work, we present a systematic large-scale analysis of neural relation classification architectures on six benchmark datasets with widely varying characteristics. We propose a novel multi-channel LSTM model combined with a CNN that takes advantage of all currently popular linguistic and architectural features. Our ‘Man for All Seasons’ approach achieves state-of-the-art performance on two datasets. More importantly, in our view, the model allowed us to obtain direct insights into the continued challenges faced by neural language models on this task. Example data and source code are available at: https://github.com/aidantee/ MASS.MR

A Time-Resolved Line-Focus Acoustic Microscopy Technique for Surface-Breaking Crack Depth Determination

Time-resolved line-focus acoustic microscopy (TRLFAM) combines the advantages of a conventional pulse-echo system with those of the acoustic microscope. Compared to high frequency line-focus acoustic microscopy [1], this technique employs a much larger (aperture 28mm) pulsed line-focus immersion transducer at much lower center frequencies. The insonified length of the specimen is an order of magnitude larger than that of the line-focus acoustic microscope operating at 225 MHz. This has the advantage that the amplitudes and the arrival times of the directly reflected wave, the leaky surface wave as well as other possible echo arrivals, can be time-resolved with considerable accuracy when the sample is moved inside the focal region of the transducer. Moreover, since the transducer is line focused, for an anisotropic material leaky surface wave arrivals can be time resolved along different directions. In earlier papers TRLFAM has been used to determine elastic constants for both isotropic and anisotropic materials [2]

Simultaneous nutrient recovery and algal biomass production from anaerobically digested sludge centrate using a membrane photobioreactor.

This study aims to evaluate the performance of C. vulgaris microalgae to simultaneously recover nutrients from sludge centrate and produce biomass in a membrane photobioreactor (MPR). Microalgae growth and nutrient removal were evaluated at two different nutrient loading rates (sludge centrate). The results show that C. vulgaris microalgae could thrive in sludge centrate. Nutrient loading has an indiscernible impact on biomass growth and a notable impact on nutrient removal efficiency. Nutrient removal increased as the nutrient loading rate decreased and hydraulic retention time increased. There was no membrane fouling observed in the MPR and the membrane water flux was fully restored by backwashing using only water. However, the membrane permeability varies with the hydraulic retention time (HRT) and biomass concentration in the reactor. Longer HRT offers higher permeability. Therefore, it is recommended to operate the MPR system in lower HRT to improve the membrane resistance and energy consumption

A Novel Approach in Crude Enzyme Laccase Production and Application in Emerging Contaminant Bioremediation

Laccase enzyme from white-rot fungi is a potential biocatalyst for the oxidation of emerging contaminants (ECs), such as pesticides, pharmaceuticals and steroid hormones. This study aims to develop a three-step platform to treat ECs: (i) enzyme production, (ii) enzyme concentration and (iii) enzyme application. In the first step, solid culture and liquid culture were compared. The solid culture produced significantly more laccase than the liquid culture (447 vs. 74 µM/min after eight days), demonstrating that white rot fungi thrived on a solid medium. In the second step, the enzyme was concentrated 6.6 times using an ultrafiltration (UF) process, resulting in laccase activity of 2980 µM/min. No enzymatic loss due to filtration and membrane adsorption was observed, suggesting the feasibility of the UF membrane for enzyme concentration. In the third step, concentrated crude enzyme was applied in an enzymatic membrane reactor (EMR) to remove a diverse set of ECs (31 compounds in six groups). The EMR effectively removed of steroid hormones, phytoestrogen, ultraviolet (UV) filters and industrial chemical (above 90%). However, it had low removal of pesticides and pharmaceuticals.</jats:p

A new perspective on small-scale treatment systems for arsenic affected groundwater

This work provides a new perspective on small-scale treatment systems to remove arsenic from groundwater for potable applications in low-income communities. Data corroborated from the literature highlight a significant challenge to providing potable water in a financially sustainable manner in arsenic affected areas. Analysis of the literature also reveals notable deficiency in the current practice, especially the overfocus on household-scale treatment systems for arsenic affected groundwater without adequate maintenance, monitoring, and a systematic cost–benefit analysis. Accurate and reliable analysis of arsenic in water samples at relevant health guideline values is costly and technologically demanding for low-income communities. Significant discrepancy in the performance of household-scale treatment systems can be attributed to the lack of maintenance and systematic monitoring. Moreover, data on the maintenance and compliance monitoring cost of small-scale arsenic treatment systems are very limited in the literature, and the available data show an exponential increase in maintenance cost per treatment capacity unit as the treatment size decreases. On the other hand, significant opportunities exist to increase performance reliability and reduce water treatment cost by taking advantage of the current digital transformation of the water sector. The analysis in this work suggests the need to reframe current practice towards commune-scale treatment systems as an interim step before centralised water supply is available

Microalgae-based carbon capture and utilization: A critical review on current system developments and biomass utilization

Carbon capture and utilization (CCU) is an emerging technology with commercial potential to convert atmospheric carbon dioxide (CO2) into net zero or negative emission products. In microalgae-based CCU, microalgae utilize CO2 and sunlight to generate biomass for commercial applications. This paper reviews the current state of microalgal culture development for CCU and highlights its potential contribution to addressing climate change challenges. Current microalgal culture systems have not been designed for high throughput biomass growth and carbon capture. Raceways, high-rate algal ponds, and photobioreactors are the most widely used for microalgal cultivation at a large-scale. The limitations of these systems are related to microalgal growth requirements. Ponds are operated at narrow depth to ensure sufficient light distribution and thus need a large land surface. CO2 gas needs to be in a dissolved form for efficient utilization by microalgae. Innovative system designs to achieve optimized distribution of light, nutrient, and CO2 utilization for enhanced biomass production are crucial to achieve large-scale CO2 capture by microalgae. Data corroborated in this review highlights several innovative techniques to deliver CO2 effectively and enhance light illumination to microalgal cells. Submerged and internal illuminations can enhance light distribution without compromising culture volume and land requirements. CO2 delivery technique selections mainly depend on CO2 sources. The carbonation column appears to be the best option regarding efficiency, easy operation, and simple design. The downstream processes of microalgal culture (i.e. harvesting, biomass utilization, and water reuse) are important to make microalgae-based CCU a significant contribution to global carbon mitigation solutions