Towards advanced simultaneous nitrogen removal and phosphorus recovery from digestion effluent based on anammox-hydroxyapatite (HAP) process: Focusing on a solution perspective.

In this paper, the state-of-the-art information on the anammox-HAP process is summarized. The mechanism of this process is systematically expounded, the enhancement of anammox retention by HAP precipitation and the upgrade of phosphorus recovery by anammox process are clarified. However, this process still faces several challenges, especially how to deal with the âˆ¼ 11% nitrogen residues and to purify the recovered HAP. For the first time, an anaerobic fermentation (AF) combined with partial denitrification (PD) and anammox-HAP (AF-PD-Anammox-HAP) process is proposed to overcome the challenges. By AF of the organic impurities of the anammox-HAP granular sludge, organic acid is produced to be used as carbon source for PD to remove the nitrogen residues. Simultaneously, pH of the solution drops, which promotes the dissolution of some inorganic purities such as CaCO3. In this way, not only the inorganic impurities are removed, but the inorganic carbon is supplied for anammox bacteria.

The volatile organic compounds and palatability of mixed ensilage of marigold (Tagetes erecta L.) crop residues.

With increasing acreage of cash crops, the use of their by-products as supplements for livestock feed becomes an important factor. Marigold (Tagetes erecta L.) account for more than half of the world's loose flower production. However, there is no precedent for the abundantly available marigold crop residue (MCR) being used as feed in agricultural production, probably because of its strong pungent taste. This study aimed to evaluate the biotransformation of the volatile organic compounds (VOCs) of MCR by mixed ensilage and assess its palatability by cattle. Caryophyllene, the most prevalent VOC in MCR, decreased by 29.11% (P < 0.05), 38.85% (P < 0.05), 37.15% (P < 0.05), and 28.36% (P < 0.05) ensilage with corn meal (CM), bran (BR), crop corn (CC), and straw (ST), respectively. The acetic acid content increased by 686.05% (P < 0.05), 1337.21% (P < 0.05), 1244.19% (P < 0.05), and 1795.34% (P < 0.05) after mixed ensilage with CM, BR, CC, and ST, respectively. The total amount of alcoholic VOCs followed an overall increasing trend during mixed storage and 10 new alcohols were obtained. Over seven days, feed intake of mixed ensilage MCR by cattle differed significantly (P < 0.05) among treatments compared with MCR and was highest in MCRCM. Combined with palatability trials, the best MCR feed intake was achieved with MCRCM. The findings shed light on how feed odor can be improved and how degradation of terpenes can be enhanced in practical applications by mixed ensilage.

A Hypoxia-Activated Prodrug Conjugated with a BODIPY-Based Photothermal Agent for Imaging-Guided Chemo-Photothermal Combination Therapy.

Hypoxia-activated prodrugs (HAPs) have drawn increasing attention for improving the antitumor effects while minimizing side effects. However, the heterogeneous distribution of the hypoxic region in tumors severely impedes the curative effect of HAPs. Additionally, most HAPs are not amenable to optical imaging, and it is difficult to precisely trace them in tissues. Herein, we carefully designed and synthesized a multifunctional therapeutic BAC prodrug by connecting the chemotherapeutic drug camptothecin (CPT) and the fluorescent photothermal agent boron dipyrromethene (BODIPY) via hypoxia-responsive azobenzene linkers. To enhance the solubility and tumor accumulation, the prepared BAC was further encapsulated into a human serum albumin (HSA)-based drug delivery system to form HSA@BAC nanoparticles. Since the CPT was caged by a BODIPY-based molecule at the active site, the BAC exhibited excellent biosafety. Importantly, the activated CPT could be quickly released from BAC and could perform chemotherapy in hypoxic cancer cells, which was ascribed to the cleavage of the azobenzene linker by overexpressed azoreductase. After irradiation with a 730 nm laser, HSA@BAC can efficiently generate hyperthermia to achieve irreversible cancer cell death by oxygen-independent photothermal therapy. Under fluorescence imaging-guided local irradiation, both in vitro and in vivo studies demonstrated that HSA@BAC exhibited superior antitumor effects with minimal side effects.

Granular activated carbon promoting re-granulation of anammox-hydroxyapatite granules for stable nitrogen removal at low phosphate concentration.

Anaerobic ammonium oxidation (anammox) coupled with hydroxyapatite (HAP) crystallization not only achieves simultaneous nitrogen removal and phosphorus recovery, but also cultivates excellent anammox granules. However, a floatation and wash-out of anammox-HAP granules was occurred at low phosphate concentrations. In this study, a reactor inoculated with mature anammox-HAP granules and fed with low phosphate (5 mg P/L) was added with granular activated carbon (GAC) to maintain sludge granulation and nitrogen-removing stability. At influent total nitrogen >800 mg/L and nitrogen loading rate ~ 9.8 kg/m3/d, a satisfactory nitrogen removal of around 88% was maintained during 140 days of operation. Insufficient phosphate supplement resulted in a sludge bulking, with suspended solid and sludge density decreased whereas sludge water content and expansion ratio increased due to HAP loss. Nevertheless, the sludge re-granulation was found at the later stage as the proportion of granules in 2.8- 3.35 mm went up to 37.4% after large granules disintegrated into small pieces at the initial stage. The settling velocity was finally ranging from 129.8 to 182.2 m/h. In addition, Candidatus Brocadia was increased from 2.1% to 20.1% and dominated in the microbial community. These findings suggest GAC was able to promote re-granulation of anammox-HAP granules at low phosphate concentration, which avoids sludge flotation and widens their application as an inoculum.

Enhancing phosphorus recovery from sewage sludge using anaerobic-based processes: Current status and perspectives.

Anaerobic-based processes are green and sustainable technologies for phosphorus (P) recovery from sewage sludges economically and are promising in practical application. However, the P release efficiency is always not satisfied. In this paper, the P release mechanisms (regarding to different P species) from sewage sludge using anaerobic-based processes are systematically summarized. The obstacles of P release and the updated achievements of enhancing P release from sewage sludges are analyzed and discussed. It can be concluded that different P species can release from sewage sludge via different anaerobic-based processes. Extracellular polymeric substances and excessive metal ions are the two main limiting factors to P release. Acid fermentation and anaerobic fermentation with sulfate reduction could be two promising ways, with P release efficiencies of up to 64% and 63%. Based on the summarization and discussion, perspectives on practical application of P recovery from sewage sludge using anaerobic-based processes are proposed.

Strategies for maximizing photothermal conversion efficiency based on organic dyes.

Photothermal therapy (PTT) has emerged as a promising therapeutic approach for tumor control and ablation. Attention has focused on exploring advanced organic photothermal agents (OPTAs), with advantages of easy modification, adjustable photophysical and photochemical properties, good compatibility, and inherent biodegradability. However, few detailed studies on how to maximally channelize nonradiative heat generation from the viewpoint of the photothermal conversion mechanism have been reported. Thus, here we assimilate and elaborate on several available action mechanisms to maximize the photothermal conversion efficiency (PCE) of organic dyes. Moreover, we also propose several potential challenges that require substantial future work to address.

Inhibition of the Citrus Canker Pathogen Using a Photosensitizer Assisted by Sunlight Irradiation.

Citrus canker, induced by bacterial infection, seriously affects the growth and productivity of citrus around the world and has attracted strong research interest. The current treatment for this disease uses copper salts to inactivate the pathogenic bacteria: Xanthomonas citri subsp. citri (Xcc) strain. However, copper salts may have a negative impact on the environment or plant. In this work, we identify a chemical compound, 2,6-diiodo-1,3,5,7-tetramethyl-8-(P-benzoic acid)-4,4'-difluoroboradiazaindacene (DIBDP), to inactivate the pathogenic Xcc strain (29-1). DIBDP is activated by sunlight and generates reactive oxygen species to kill the bacteria. In order to overcome the degradation of DIBDP under sunlight, an adjuvant agent was identified to limit the photodegradation of DIBDP by forming a photosensitizer complex (PSC). This complex demonstrated significant antimicrobial activity to Xcc 29-1, which was 64-fold more potent than the copper biocides. The antimicrobial efficacy of PSC on citrus leaves infected by Xcc 29-1 also was much stronger than copper agent and, at the same time, the PSC was safe to the host exposed to sunlight. Thus, this PSC is a promising antibacterial agent to control citrus canker disease.

Assessment of ramie leaf (Boehmeria nivea L. gaud) as an animal feed supplement in P.R. China.

Tropical and subtropical regions were quite short of high-quality protein forage. Ramie (Boehmeria nivea L. Gaud) leaves as crop by products, are rich in protein and widely cultivated in tropical and subtropical regions. Thence, the development and utilization of ramie is of great significance to animal production in these regions. But it contained high level of tannins and total phenols, which may produce potentially adverse effect. It is very essential to evaluate the safety of ramie leaves before they are used as feed supplements. To evaluate potential toxic level of ramie leaf, control group, low dose and high dose (0, 1, 2 g/kg·BW) groups of ramie leaf were conducted orally in Sprague-Dawley rats (SD rats). Body weight, hematology, and histopathology was assessed during 28 d of treatment and 14 d of recovery period. The results showed that there were no toxic symptoms appeared in the treated and control groups. There were a few individual indicators showed abnormal, but most indices of body weight, organ weight ratios and hematology were normal. And compared to control group, it showed no significant differences (P>0.05). Histopathological examination of the high dose group and control group showed that there was no lesions related to ramie administration. The pathological changes appeared in the liver, and lungs of rats in individual rat of both groups were common and spontaneous, and had no significant differences (P>0.05). These results suggest that under this experimental condition, up to 2 g/kg·BW intragastric administration of ramie leaf did not produce adverse effect to SD rats. These findings would provide available information for ramie leaf to utilize as a feed supplement, particularly in P.R. China.

Carbon source and phosphorus recovery from iron-enhanced primary sludge via anaerobic fermentation and sulfate reduction: Performance and future application.

Anaerobic fermentation and sulfate reduction (AF-SR) was firstly used for recovery of carbon sources and phosphorus from Fe-enhanced primary sludge (Fe-sludge). With FeCl3 dosage of 30 mg Fe/L, 63.0% of the chemical oxygen demand (COD) and 97.3% of the phosphorus were concentrated from sewage into Fe-sludge. Batch anaerobic fermentation tests of Fe-sludge with and without sulfate addition (AF-SR and control) were performed. The results showed that volatile fatty acid concentrations of the control and AF-SR were 211.0 and 270.2 mg COD/g volatile suspended solids, respectively. Furthermore, 33.2% (control) and 56.2% (AF-SR) of the total phosphorus in Fe-sludge was released. The recovery performances of carbon source and phosphorus were calculated based on struvite precipitation. The available carbon source of the AF-SR system was 44.5% higher than that of the control. A novel integrated wastewater and sludge treatment process based on chemically enhanced primary sedimentation and AF-SR is proposed for future application.

High-Dose Electron Radiation and Unexpected Room-Temperature Self-Healing of Epitaxial SiC Schottky Barrier Diodes.

Silicon carbide (SiC) has been widely used for electronic radiation detectors and atomic battery sensors. However, the physical properties of SiC exposure to high-dose irradiation as well as its related electrical responses are not yet well understood. Meanwhile, the current research in this field are generally focused on electrical properties and defects formation, which are not suitable to explain the intrinsic response of irradiation effect since defect itself is not easy to characterize, and it is complex to determine whether it comes from the raw material or exists only upon irradiation. Therefore, a more straightforward quantification of irradiation effect is needed to establish the direct correlation between irradiation-induced current and the radiation fluence. This work reports the on-line electrical properties of 4H-SiC Schottky barrier diodes (SBDs) under high-dose electron irradiation and employs in situ noise diagnostic analysis to demonstrate the correlation of irradiation-induced defects and microscopic electronic properties. It is found that the electron beam has a strong radiation destructive effect on 4H-SiC SBDs. The on-line electron-induced current and noise information reveal a self-healing like procedure, in which the internal defects of the devices are likely to be annealed at room temperature and devices' performance is restored to some extent.

Simultaneous release of polyphosphate and iron-phosphate from waste activated sludge by anaerobic fermentation combined with sulfate reduction.

Iron is widely used in sewage treatment systems and enriched into waste activated sludge (WAS), which is difficult and challenging to phosphorus (P) release and recovery. This study investigated simultaneous release performance of polyphosphate and iron-phosphate from iron-rich sludge via anaerobic fermentation combined with sulfate reduction (AF-SR) system. Batch tests were performed, with results showing that AF-SR system conducted a positive effect due to the relatively low solubility of ferrous sulfide in comparison with ferric phosphate precipitates. Simulation study was performed to investigate the total P release potential from actual waste activated sludge, finding that about 70% of the total P could release with the optimized pH of 7.0-8.0 and the theoretical S2-/Fe2+ molar ratio of 1.0. A potential new blueprint of a wastewater treatment plant based on AF-SR system, towards P, N recovery and Fe, S, C recycle, was finally proposed.

Phosphorus and short-chain fatty acids recovery from waste activated sludge by anaerobic fermentation: Effect of acid or alkali pretreatment.

Waste activated sludge (WAS) was pretreated by acid or alkali to enhance the anaerobic fermentation (AF) for phosphorus (P) and short-chain fatty acids (SCFAs) release into the liquid simultaneously. With acid pretreatment, the released total P concentration achieved 120mg/L, which was 71.4% higher than that with alkali pretreatment. In addition, alkali pretreatment enhanced organic P release with about 35.3% of organic P in the solid being converted to inorganic P, while little had changed with acid pretreatment. The results also showed that acid and alkali pretreatment enhanced SCFAs production by 15.3 and 12.5times, respectively. Acid pretreatment could be preferred for simultaneous recovery of P and SCFAs by AF.

Role of extracellular polymeric substances in enhancement of phosphorus release from waste activated sludge by rhamnolipid addition.

This study investigated the role of extracellular polymeric substances (EPSs) in enhanced performance of phosphorus (P) release from waste activated sludge (WAS) by adding rhamnolipid (RL). Results showed that compared to WAS without pretreatment, the released PO4(3-)-P increased with RL addition from 0 to 0.2 g/gTSS (total suspended solid), and increased by 208% under the optimal condition (0.1 g RL/g TSS and 72-h fermentation time). The cumulative PO4(3-)-P was better fitted with pseudo-first-order kinetic model. Moreover, the contents of metal ions increased in liquid but decreased in EPSs linearly with RL addition increasing, and WAS solubilizations were positively correlated with the released metal ions. The enhanced total dissolved P mainly came from cells and others (69.39%, 2.27-fold higher than that from EPSs), and PO4(3-)-P was the main species in both liquid and loosely bound EPSs, but organic P should be non-negligible in tightly bound EPSs.

Phosphorus recovery from microbial biofuel residual using microwave peroxide digestion and anion exchange.

Sustainable production of microalgae for biofuel requires efficient phosphorus (P) utilization, which is a limited resource and vital for global food security. This research tracks the fate of P through biofuel production and investigates P recovery from the biomass using the cyanobacterium Synechocystis sp. PCC 6803. Our results show that Synechocystis contained 1.4% P dry weight. After crude lipids were extracted (e.g., for biofuel processing), 92% of the intracellular P remained in the residual biomass, indicating phospholipids comprised only a small percentage of cellular P. We estimate a majority of the P is primarily associated with nucleic acids. Advanced oxidation using hydrogen peroxide and microwave heating released 92% of the cellular P into orthophosphate. We then recovered the orthophosphate from the digestion matrix using two different types of anion exchange resins. One resin impregnated with iron nanoparticles adsorbed 98% of the influent P through 20 bed volumes, but only released 23% during regeneration. A strong-base anion exchange resin adsorbed 87% of the influent P through 20 bed volumes and released 50% of it upon regeneration. This recovered P subsequently supported growth of Synechocystis. This proof-of-concept recovery process reduced P demand of biofuel microalgae by 54%.

[Comparison research on quality of cultivated and wild Anemarrhena Rhizome from Yi County].

OBJECTIVE: To compare the quality of cultivated and wild Anemarrhena Rhizome from Yi County (Xiling Zhimu) based on contents analysis of active constituents. METHOD: Samples of cultivated Anemarrhena Rhizome from most townships of Yi County were analyzed and compared with wild ones. Six indexes belonged to three kinds active constituents of saponin, flavornoid and polysaccharide were adopted. HPLC-ELSD method with cholesterol as internal standard was adopted to determine the content of sarsasapongenin. HPLC-ELSD method was used to simultaneously determine the contents of anemasaponin C and Anemasaponin A III. Contents of neomangiferin and mangiferin were determined by HPLC-UV method. Total polysaccharide was determined by phenol sulfate method. RESULT: The mean content of sarsasapongenin in cultivated Anemarrhena Rhizome samples is slightly lower than the wild. The mean contents of anemasaponin C and Anemasaponin A III in cultivated Anemarrhena Rhizome samples are higher than the wild. There is no notable difference of these three index between the cultivated and the wild. The cultivated Anemarrhena Rhizome samples have a lower content of neomangiferin and a higher content of mangiferin than the wild. While the total content of these two flavonoids have no notable difference. The cultivated Anemarrhena Rhizome samples have a higher content of total polysaccharide than the wild samples. CONCLUSION: Contents of active constituents in cultivated Anemarrhena Rhizome from Yi County (Xiling Zhimu) are not notably different with the wild Anemarrhena Rhizome. They have similar good quality as the wild ones.

The effect of calcium on the treatment of fresh leachate in an expanded granular sludge bed bioreactor.

This research investigated the calcium effect on the anaerobic treatment of fresh leachate in an expanded granular sludge bed (EGSB) bioreactor under mesophilic conditions. The observations show that the bioreactor, inoculated with anaerobic granular sludge, can be started up only in about 40 days for the treatment of calcium-containing fresh leachate with chemical oxygen demand (COD) removal efficiency above 90% and organic loading rate up to 72.84 kg COD/m(3) day. The calcium accumulation onto the granules was monotonically related to the calcium concentration, accounting for 17-18 wt.% of Ca in the suspended solid in the form of calcium carbonate, phosphates/phosphonates and carboxylates. The mineral formation significantly increased the granule settling velocity (by ∼ 50%) and the suspended solid concentration (by ∼ 100%). However, the effect of calcium precipitation on the specific methanogenic activity and the CH(4) production rate was complex, first positive during the start-up but later on negative.