Algal-bacterial aerobic granular sludge for real municipal wastewater treatment: Performance, microbial community change and feasibility of lipid recovery.

Despite various research works on algal-bacterial aerobic granular sludge for wastewater treatment and resource recovery processes, limited information is available on its application in real wastewater treatment in terms of performance, microbial community variation and resource recovery. This study investigated the performance of algal-bacterial aerobic granular sludge on real low-strength wastewater treatment in addition to the characterization of microbial community and fatty acid compositions for biodiesel production. The results demonstrated 71% COD, 77% NH4+-N and 31% phosphate removal efficiencies, respectively. In addition, all the water parameters successfully met the effluent standard A, imposed by the Department of Environment (DOE) Malaysia. Core microbiome analyses revealed important microbial groups (i.e., Haliangium ochraceum, Burkholderiales and Chitinophagaceae) in bacterial community. Meanwhile the photosynthetic microorganisms, such as Oxyphotobacteria and Trebouxiophyceae dominated the algal-bacterial aerobic granular sludge, suggesting their important roles in granulation and wastewater treatment. Up to 12.51 mg/gSS lipid content was recovered from the granules. In addition, fatty acids composition showed high percetages of C16:0 and C18:0, demonstrating high feasibility to be used for biodiesel production application indicated by the cetane number, iodine value and oxidation stability properties.

Discovering future research trends of aerobic granular sludge using bibliometric approach.

The advantageous characteristics of aerobic granular sludge (AGS) have led to their increasing popularities among academics and industrial players. However, there has been no bibliometric report on current and future research trends of AGS. This study utilized the available reports of AGS in the Scopus database for comprehensive bibliometric analyses using VOSviewer software. A total of 1203 research articles from 1997 to 2020 were analyzed. The dominance of the Netherlands and China were revealed by the high number of publications and citations. Nevertheless, the Netherlands exhibited higher average citation per article at 76.4. A recent process of AGS involving biochar and algal addition were also identified. Meanwhile, the application of AGS for antibiotic containing wastewater as well as possibility of resource recovery were recently reported and was expected to expand in the future. It was suggested that application of AGS would develop further along with the development of sustainable wastewater treatment process.

Characteristics of algal-bacterial aerobic granular sludge treating real wastewater: Effects of algal inoculation and alginate-like exopolymers recovery.

Limited information is available on the characteristics of algal-bacterial aerobic granular sludge (AGS) treating real wastewater, especially on its alginate-like exopolymers (ALE) production. In addition, the effect of target microalgae species inoculation on the system performance has not been fully understood. This study aimed to reveal the effect of microalgae inoculation on the characteristics of algal-bacterial AGS and its ALE production potential. Two photo-sequencing batch reactors (PSBR) were employed, namely R1 with activated sludge and R2 with Tetradesmus sp. and activated sludge being inoculated, respectively. Both reactors were fed with locally sourced municipal wastewater and operated for 90 days. Algal-bacterial AGS were successfully cultivated in both reactors. No significant difference was observed between the performances of R1 and R2, reflecting that the inoculation of target microalgae species may not be crucial for the development of algal-bacterial AGS when treating real wastewater. Both reactors achieved an ALE yield of about 70 mg/g of volatile suspended solids (VSS), indicating that a substantial amount of biopolymer can be recovered from wastewater. Interestingly, boron was detected in all the ALE samples, which might contribute to granulation and interspecies quorum sensing. The enrichment of lipids content in ALE from algal-bacterial AGS treating real wastewater reveals its high resource recovery potential. Overall, the algal-bacterial AGS system is a promising biotechnology for simultaneous municipal wastewater treatment and resource (like ALE) recovery.

Acute toxicity and morphology alterations of glyphosate-based herbicides to Daphnia magna and Cyclops vicinus.

Zooplankton is very sensitive to various agrochemicals including glyphosate herbicides which may arise from runoff in paddy fields. In this study, acute toxicity test of Glyphosate-Based Herbicides (GBHs) was conducted to Daphnia magna and Cyclops vicinus. Acute toxicity test was performed to both organisms at the Glyphosate concentrations of 20, 80, 160, 320, and 640 mg/L in exposure time of 12 h, 24 h, and 48 h. The mortality and morphology were observed to determine the LC50 and the effect of its morphology. The test showed that D. magna was more susceptible than C. vicinus. The LC50 of GBHs to D. magna and C. vicinus for its different exposure time were respectively show as follows: 76.67 mg/L and 207.89 mg/L (12 h); 36.2 mg/L and 159.8 mg/L (24 h); and 21.34 mg/L and 92.93 mg/L (48 h). There were no significant differences of the alteration of spin length, body length, and head length of D. magna to exposure of GBHs, except the head width. While body length alteration of C. vicinus was significantly different towards the increase in concentration.

The effects of particulate matters inhalation exposures of prallethrin and d-phenothrin mixture in mice (Mus musculus) against exhaled carbon dioxide concentration.

Particulate matter (PM) inhalation exposure affects exhaled CO2 concentration. Such exhaled CO2 refers to ventilation and perfusion of the cardiorespiratory system, the analysis of which is painless, non-invasive and simple to perform. This study examined the effect of prallethrin and d-phenothrin inhalation exposure on exhaled CO2 in mice using a simple method. Prallethrin and d-phenothrin were administered in male mice (Mus musculus) in a series of repeated inhalation exposures of lower and higher doses for 60 days. The lower dose was a mixture of 0.000141 mg/L prallethrin and 0.104 mg/L d-phenothrin, while the higher dose was a mixture of 0.00141 mg/L prallethrin and 1.04 mg/L d-phenothrin. The lower dose was based on a NOAEL value of prallethrin and d-phenothrin of 28 days exposure, while the higher one was ten times of the lower dose concentration. CO2 concentration was measured by means of the passage through NaOH 0.1 N, titrated by HCl 0.1 N. PMs were generated by the process of producing bubbles, inserted into the chamber containing mice. Mice were divided into four groups, namely: negative control (NC), positive control (PC), and lower- and higher-dose treatment groups, with three replicates for each group. Statistical difference analyses were observed in body weight and exhaled CO2 concentration between negative control and treatment groups, nevertheless, they did not differ significantly between the control and the treatment (lower and higher dose) groups. This study suggests that exhaled CO2 and body weight are not specific biomarkers to observe PMs inhalation exposure with respect to prallethrin and d-phenothrin mixtures.

Performance of geotextile-based slow sand filter media in removing total coli for drinking water treatment using system dynamics modelling.

In a slow sand filter, a biological layer consisting of alluvial mud and various types of microorganisms grows and attaches to the sand media and forms a matrix called schmutzdecke. Changes to several factors, including the quality of raw water, filtration speed, and the addition of media, affect the performance of the slow sand filter unit in producing treated water. Geotextiles can be equipped to improve the performance of a slow sand filter in removing pollutants. The selection of several factors that affect slow sand filter performance can be used as a starting point for the engineering system to determine the best pattern of performance behavior. This approach was carried out by looking at the dynamic behavior patterns of slow sand filter system performance in treating raw water. This research has not yet been conducted extensively. The dynamic behavior pattern approach to the performance of the slow sand filter unit was used to obtain the behavior model for the schmutzdecke layer on the filter. The system dynamic approach focused on treatment scenarios that can determine the behavior of the slow sand filter system. Several factors were assessed, including temperature, turbidity, nutrient concentration, algal concentration, bacteria and dissolved oxygen. Model simulation results show that the comparison of C: N: P values affected the performance of the schmutzdecke layer in removing total coli. The slow sand filter unit was capable of producing treated water with a total amount of coli equal to 0 on the C: N: P values of 85: 5.59: 1.25, respectively, and a 9 cm geotextile thickness.