Microtia, Branchial Cleft Fistula, and Tetralogy of Fallot: A Possible Association.

When searching over associations between congenital ear abnormalities, especially microtia and affiliated deformities like cleft lip or palate and congenital heart diseases, some clinical analysis and genetic theories are found. A 10-year-old boy sent to the plastic surgery hospital was puzzled by a congenital anterior auricular fistula with fluid trace for more than 9 years. The preoperative diagnoses were branchial cleft fistula and congenital left ear deformity with postoperation of TOF. By browsing over studies on genetic concerns and clinical performance, it may be attributed to a possible association between microtia, branchial cleft fistula, and tetralogy of Fallot, though whose fundamental mechanisms remain concerned.

A 20-year shift in China's sewage sludge heavy metals and its feasibility of nutrient recovery in land use.

Recycling resources from wastewater is even more important for developing a more sustainable society. Disposing sewage sludge, which accumulates most pollutants and resources in sewage, is the main challenge in wastewater pollution control and resource utilization. Heavy metals (HMs) are the greatest constraint limiting the application of sewage sludge to land as a sustainable use of this material. We conducted a meta-analysis of the concentrations of HMs in Chinese sewage sludge by combining data from studies published from 2000 to 2019 (N = 8477). Over this period, the reported concentrations of HMs in sewage sludge declined in three stages (a fluctuating stage, a slight decrease stage, and a rapid and stable decrease stage). The results revealed that economic development and environmental policy implementation were the main factors mitigating HM pollution in sewage sludge in China. Moreover, if environmental regulations were strengthened and HM pollution-mitigation strategies were made consistent, such that the proportion of sewage sludge applied to land in China could be increased from 18.6% to 48.0% (the proportion applied to land in the United States), the ecosystem services analysis showed that huge ecological-economic benefits could be realized (3.1 billion Chinese Yuan) and the use of fertilizers could be substantially reduced (the use of nitrogen fertilizers by 8.5% and the use of phosphate fertilizers by 18.1%). This review shows that China should formulate a unified policy and interdepartmental committee for sustainable application of sewage sludge to land and wastewater resource recycling management.

Analysis of clinicopathological features and prognostic factors of breast cancer brain metastasis.

BACKGROUND: Breast cancer (BC) has become the most common malignancy in women. The incidence and detection rates of BC brain metastasis (BCBM) have increased with the progress of imaging, multidisciplinary treatment techniques and the extension of survival time of BC patients. BM seriously affects the quality of life and sur-vival prognosis of BC patients. Therefore, clinical research on the clinicopathological features and prognostic factors of BCBM is valuable. By analyzing the clinicopathological parameters of BCBM patients, and assessing the risk factors and prognostic indicators, we can perform hierarchical diagnosis and treatment on the high-risk population of BCBM, and achieve clinical benefits of early diagnosis and treatment. AIM: To explore the clinicopathological features and prognostic factors of BCBM, and provide references for diagnosis, treatment and management of BCBM. METHODS: The clinicopathological data of 68 BCBM patients admitted to the Air Force Medical Center, Chinese People's Liberation Army (formerly Air Force General Hospital) from 2000 to 2022 were collected. Another 136 BC patients without BM were matched at a ratio of 1:2 based on the age and site of onset for retrospective analysis. Categorical data were subjected to χ2 test or Fisher's exact probability test, and the variables with P < 0.05 in the univariate Cox proportional hazards model were incorporated into the multivariate model to identify high-risk factors and independent prognostic factors of BCBM, with a hazard ratio (HR) > 1 suggesting poor prognostic factors. The survival time of patients was estimated by the Kaplan-Meier method, and overall survival was compared between groups by log-rank test. RESULTS: Multivariate Cox regression analysis showed that patients with stage III/IV tumor at initial diagnosis [HR: 5.58, 95% confidence interval (CI): 1.99-15.68], lung metastasis (HR: 24.18, 95%CI: 6.40-91.43), human epidermal growth factor receptor 2 (HER2)-overexpressing BC and triple-negative BC were more prone to BM. As can be seen from the prognostic data, 52 of the 68 BCBM patients had died by the end of follow-up, and the median time from diagnosis of BC to the occurrence of BM and from the occurrence of BM to death or last follow-up was 33.5 and 14 mo, respectively. It was confirmed by multivariate Cox regression analysis that patients with neurological symptoms (HR: 1.923, 95%CI: 1.005-3.680), with bone metastasis (HR: 2.011, 95%CI: 1.056-3.831), and BM of HER2-overexpressing and triple-negative BC had shorter survival time. CONCLUSION: HER2-overexpressing, triple-negative BC, late tumor stage and lung metastasis are risk factors of BM. The presence of neurological symptoms, bone metastasis, and molecular type are influencing prognosis factors of BCBM.

Peutz-Jeghers syndrome without STK11 mutation may correlate with less severe clinical manifestations in Chinese patients.

BACKGROUND: Peutz-Jeghers syndrome (PJS) is an autosomal dominant genetic disease with skin mucosal pigment spots and gastrointestinal (GI) multiple hamartoma polyps as clinical characteristics. At present, it is considered that the germline mutation of STK11 gene is the genetic cause of PJS. However, not all PJS patients can be detected STK11 germline mutations. The specific clinical characteristics of these PJS patients without STK11 mutation is an interesting clinical question. Or, like wild type GI stromal tumor, whether these PJS without STK11 mutation are also called PJS is worth discussing. Therefore, we designed the study to understand the clinical characteristics of these PJS patients without STK11 mutation. AIM: To investigates whether PJS patients with known STK11 mutations have a more severe spectrum of clinical phenotypes compared to those without. METHODS: A total of 92 patients with PJS admitted to the Air Force Medical Center from 2010 to 2022 were randomly selected for study. Genomic DNA samples were extracted from peripheral blood samples, and pathogenic germline mutations of STK11 were detected by high-throughput next-generation gene sequencing. Clinical-pathologic manifestations of patients with and without STK11/LKB1 mutations were compared. RESULTS: STK11 germline mutations were observed in 73 patients with PJS. Among 19 patients with no detectable STK11 mutations, six had no pathogenic germline mutations of other genes, while 13 had other genetic mutations. Compared with PJS patients with STK11 mutations, those without tended to be older at the age of initial treatment, age of first intussusception and age of initial surgery. They also had a lower number of total hospitalizations relating to intussusception or intestinal obstruction, and a lower load of small intestine polyps. CONCLUSION: PJS patients without STK11 mutations might have less severe clinical-pathologic manifestations than those with.

Clinical features, diagnosis, and treatment of Peutz-Jeghers syndrome: Experience with 566 Chinese cases.

BACKGROUND: Peutz-Jeghers syndrome (PJS) is a clinically rare disease with pigmented spots on the lips and mucous membranes and extremities, scattered gastrointestinal polyps, and susceptibility to tumors as clinical manifestations. Effective preventive and curative methods are still lacking. Here we summarize our experience with 566 Chinese patients with PJS from a Chinese medical center with regard to the clinical features, diagnosis, and treatment. AIM: To explore the clinical features, diagnosis, and treatment of PJS in a Chinese medical center. METHODS: The diagnosis and treatment information of 566 cases of PJS admitted to the Air Force Medical Center from January 1994 to October 2022 was summarized. A clinical database was established covering age, gender, ethnicity, family history, age at first treatment, time and sequence of appearance of mucocutaneous pigmentation, polyp distribution, quantity, and diameter, frequency of hospitalization, frequency of surgical operations, etc. The clinical data was retrospectively analyzed using SPSS 26.0 software, with P < 0.05 considered statistically significant. RESULTS: Of all the patients included, 55.3% were male and 44.7% were female. Median time to the appearance of mucocutaneous pigmentation was 2 years, and median time from the appearance of mucocutaneous pigmentation to the occurrence of abdominal symptoms was 10 years. The vast majority (92.2%) of patients underwent small bowel endoscopy and treatment, with 2.3% having serious complications. There was a statistically significant difference in the number of enteroscopies between patients with and without canceration (P = 0.004, Z = -2.882); 71.2% of patients underwent surgical operation, 75.6% of patients underwent surgical operation before the age of 35 years, and there was a statistically significant difference in the frequency of surgical operations between patients with and without cancer (P = 0.000, Z = -5.127). At 40 years of age, the cumulative risk of intussusception in PJS was approximately 72.0%, and at 50 years, the cumulative risk of intussusception in PJS was approximately 89.6%. At 50 years of age, the cumulative risk of cancer in PJS was approximately 49.3%, and at 60 years of age, the cumulative risk of cancer in PJS was approximately 71.7%. CONCLUSION: The risk of intussusception and cancer of PJS polyps increases with age. PJS patients ≥ 10 years old should undergo annual enteroscopy. Endoscopic treatment has a good safety profile and can reduce the occurrence of polyps intussusception and cancer. Surgery should be conducted to protect the gastrointestinal system by removing polyps.

Effects of Nitrogen Deficiency on the Metabolism of Organic Acids and Amino Acids in Oryza sativa.

Organic acids metabolism and nitrogen (N) metabolism in rice seedlings and the relationship between them are not fully understood. In this study, rice (Oryza sativa L. ssp. Indica) variety "Huanghuazhan" was used as the experimental material, and three N levels (5 mM, 1 mM, and 0 mM NH4NO3) were set by the hydroponic method for different levels of N treatment. Our results showed that the increased content of malate in rice leaves caused by reducing N level was related to the increased synthesis of malate (the activity of leaf PEPC increased)and the decreased degradation of malate (the activity of leaf NADP-ME decreased), while the increased contents of citrate and isocitrate in rice leaves caused by reducing N level might not be caused by the increased biosynthesis, but due to the decrease in degradation of citrate and isocitrate (the activities of leaf CS, ACO, and NADP-IDH decreased). The increased content of malate in rice roots caused by reducing N level might be related to the increased biosynthesis and the decreased degradation of root malate (the activities of root NAD-MDH and PEPC increased, while the activity of NADP-ME decreased). Compared to the control (5 mM NH4NO3), the increased content of citrate in rice roots caused by reducing N level might be related to the increased biosynthesis rather than the decreased degradation of citrate, due to the higher activities of CS and ACO in rice roots under 0 mM N and 1mM N treatment when compared to that of the control ones. At the same time, the increased content of isocitrate in roots was related to the increased isomerization of isocitrate (the activity of root ACO increased) and the decreased degradation of isocitrate (the activity of root NADP-IDH decreased). With the reducing N level, the activities of N metabolism-related enzymes, such as nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), decreased in rice leaves and roots, resulting in the decreased contents of total free amino acids (TFAAs) and soluble proteins in rice seedlings, and finally led to the growth inhibition. Our results showed that the dynamics of organic acids metabolism caused by reducing N level were different in rice leaves and roots. In conclusion, there was a close correlation between organic acids metabolism and N metabolism in rice leaves and roots under N-limited conditions; furthermore, such a correlation was more obvious in rice leaves than that of roots.

Hoffa's fracture in an adolescent treated with an innovative surgical procedure: A case report.

BACKGROUND: Hoffa fracture is rare, especially in adolescents, and has a high rate of complications such as avascular necrosis and osteoarthritis; moreover, there are no definitive guidelines for its treatment. This report could provide a new potential treatment for Hoffa fracture. CASE SUMMARY: A 16-year-old girl presented to the orthopedic emergency department of No. 2 People's Hospital of Yibin City with persistent pain following a right knee injury sustained during a sprint race. Her knee was swollen and tender, and the range of motion was restricted by the pain. X-ray and computed tomography revealed a Hoffa fracture in the right knee. After consultation, surgical treatment was performed, and the fracture was fixed with three 3.5-mm cannulated cancellous screws; osteochondral plugs that were harvested from the screw insertion site were re-implanted to cover the screw head. The patient's fracture and osteochondral plug healed 6 mo postoperatively, and she presented a knee range of motion of 0-135 without pain, and was walking without support with a normal gait. CONCLUSION: Here, we describe an innovative surgical procedure for Hoffa fracture that could provide a new possibility for the treatment of similar fractures, and further improve their management.

The effects of a multi-disciplinary team on sleep quality assessment in mild-to-moderate Alzheimer's disease patients with sleep disorders.

BACKGROUND AND AIMS: Sleep disturbances are a severe problem among patients with Alzheimer's disease (AD). By evaluating sleep quality in mild-to-moderate AD patients, this study aimed to assess the effects of multi-disciplinary team (MDT) in reducing the incidence of adverse reactions of AD patients. The reduction in the incidence of adverse reactions to predict multi-disciplinary team (MDT) treatment effects. METHODS AND RESULTS: This study included 60 mild-to-moderate AD patients with sleep problems when hospitalized in Huzhou Third Municipal Hospital. The patients were randomly distributed into two groups, routine and MDT treatments. The cognitive functions, sleep conditions, and psycho-behavioral symptoms were compared between both the groups. Cognitive function declined significantly between pretherapy and follow-up in the routine treatment group (MMSE: t = -7.961, P < 0.001; MoCA: t = -4.672, P < 0.001). There was a significant decline in drowsiness in the MDT group compared to that in the routine treatment group (χ2 = 4.320, P = 0.038). Sleep quality improved significantly during the follow-up in the MDT treatment group (t = 6.098, P < 0.001). The results of the Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA) among family caregivers (FCGs) demonstrated that MDT treatment could alleviate caregivers' depression (t = -2.867, P = 0.042), and routine treatment can worsen their anxiety (t = 3.258, P = 0.003). CONCLUSION: The MDT treatment method as an effective and meaningful therapy can help mitigate the suffering of patients with AD and FCGs.

Identification of Proteins of Tobacco Mosaic Virus by Using a Method of Feature Extraction.

Tobacco mosaic virus, TMV for short, is widely distributed in the global tobacco industry and has a significant impact on tobacco production. It can reduce the amount of tobacco grown by 50-70%. In this research of study, we aimed to identify tobacco mosaic virus proteins and healthy tobacco leaf proteins by using machine learning approaches. The experiment's results showed that the support vector machine algorithm achieved high accuracy in different feature extraction methods. And 188-dimensions feature extraction method improved the classification accuracy. In that the support vector machine algorithm and 188-dimensions feature extraction method were finally selected as the final experimental methods. In the 10-fold cross-validation processes, the SVM combined with 188-dimensions achieved 93.5% accuracy on the training set and 92.7% accuracy on the independent validation set. Besides, the evaluation index of the results of experiments indicate that the method developed by us is valid and robust.

Gastrointestinal Regulation of Red Yeast Rice on Mice with Syndrome of Food Retention Due to Spleen Deficiency Before and After Fermentation / 中国实验方剂学杂志

Objective: To investigate gastrointestinal regulation of red yeast rice on spleen deficient dyspepsia mice, and provide reference for clarifying mechanism of invigorating spleen to promote digestion of fermented traditional Chinese medicine. Method: Mice were randomly divided into 5 groups, including the blank group, the model group, the unfermented red yeast rice treatment group (1.17 g·kg-1·d-1), the fermented red yeast rice treatment group (1.17 g·kg-1·d-1), the domperidone group (3.9 mg·kg-1·d-1), ten mice in each group were continuous intragastric administration for 10 days. The effects of red yeast rice before and after fermentation on the general behavior, body weight, food intake and gastrointestinal function of spleen deficient dyspepsia mice were compared. The effects of red yeast rice on the gastrointestinal hormone[motilin (MTL), gastrin (GAS), 5-hydroxytryptamine (5-HT), vasoactive intestinal peptide (VIP)] levels in serum of spleen deficient dyspepsia mice were determined by enzyme-linked immunosorption assay (ELISA). The regulation function of red yeast rice on the pathological changes of gastrointestinal tissue of spleen deficient dyspepsia mice was investigated by hematoxylin-eosin (HE) staining. The effect of red yeast rice on gut microbiota of spleen deficient dyspepsia mice was investigated, the primers were designed on bacterial 16S rRNA V3-V4 region sequences and Illumina Miseq platform was used for high-throughput sequencing. Result: Compared with the model group, fermented red yeast rice could recover the body weight and food intake, reduce gastric residual rate (PPEscherichia-Shigella, while increasing the relative abundance of the beneficial bacteria such as Lactobacillus and Bifidobacterium. Conclusion: Fermented red yeast rice can enhance the gastrointestinal function of spleen deficient dyspepsia mice, the mechanism may be related to regulating gastrointestinal hormone level, improving histopathology of gastrointestinal tissue and restoring intestinal flora structure.

Inhibition of prostate cancer DU145 cell growth with small interfering RNA targeting the SATB1 gene.

Prostate cancer is a common visceral cancer of men worldwide. It is important to develop a more effective treatment for prostate cancer to overcome the treatment resistance that occurs with recurrence. RNA interference has been demonstrated to be a powerful tool for gene knockdown and has potential as a cancer treatment. It has been previously demonstrated that staining of special AT-rich sequence-binding protein 1 (SATB1) was stronger in prostatic carcinoma with metastasis compared with prostatic carcinoma without metastasis. In the present study, SATB1 small interfering (si)RNA was transfected into prostate cancer DU145 cells and normal human lung fibroblast cells, and cell proliferation was investigated using a Cell Counting kit-8. Three siRNA were transfected into cells using siPORT Lipid Transfection agent, and blank control and negative control groups were established. The cells were harvested and SATB1 mRNA and protein expression was determined by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. DU145 cell adhesion, migration and invasion capabilities were determined using cell adhesion, Transwell and Transwell with Matrigel assays, respectively. Silencing SATB1 significantly inhibited DU145 cell growth, adhesion, migration and invasive capability in vitro, indicating that a SATB1-targeting siRNA was successfully engineered. The results of the present study suggest that SATB1 siRNA may be a potential agent for treating human prostate cancer.

Expression of Wnt/ß-catenin related genes after skeletal muscle contusion.

BACKGROUND: It was aimed to determine expressions of genes related to Wnt/ß-catenin signaling for evaluating time duration after skeletal muscle contusion. METHODS: Pathological change of skeletal muscle was observed after H-E staining. mRNA of respective genes was quantified with real-time quantitative PCR. Expression of ß-catenin was further characterized with immunostaining and quantified as intensity/area and further immune blotting and quantified as grey intensity normalized to loading control (GADPH). RESULTS: After injury, skeletal muscle exhibited prominent inflammatory response, hyperplasia and regeneration. Infiltration of inflammatory cell, formation of myotube and maturation of skeletal muscle fiber were observed under HE staining. Expression of FZD4, Myo D, Myf5 changed during early stages after injury and could serve to evaluate injury within 24 h; Expression of SFRP5 and Fra1 changed during early-to-intermediate stages after injury and could serve to evaluate injury within 12-48 h; Expression of MRF4 changed during intermediate stages after injury and could serve to evaluate injury within 36-48 h; Expression of ß-catenin changed during intermediate stages after injury and could serve to evaluate injury within 36 h-3 d; Expression of MyoG changed during late stages after injury and could serve to evaluate injury within 48 h-7 d. Immunostaining experiments showed that 36 h after injury, membrane ß-catenin decreased while nucleus ß-catenin increased. CONCLUSION: Wnt/ß-catenin related genes are involved in regeneration of skeletal muscle after contusion. The sequential changes of gene expression can be used for evaluating the duration after contusion.

[Characteristics of rainfall and runoff in urban drainage based on the SWMM model.] / 基于SWMM模型的城市排水区域降雨及地表产流特征.

The characteristics of 235 rainfall and surface runoff events, from 2009 to 2011 in a typical urban drainage area in Shanghai were analyzed by using SWMM model. The results showed that the rainfall events in the region with high occurrence frequency were characterized by small rainfall amount and low intensity. The most probably occurred rainfall had total amount less than 10 mm, or mean intensity less than 5 mm·h-1,or peak intensity less than 10 mm·h-1, accounting for 66.4%, 88.8% and 79.6% of the total rainfall events, respectively. The study was of great significance to apply low-impact development to reduce runoff and non-point source pollution under condition of less rainfall amount or low mean rainfall intensity in the area. The runoff generally increased with the increase of rainfall. The threshold of regional occurring runoff was controlled by not only rainfall amount, but also mean rainfall intensity and rainfall duration. In general, there was no surface runoff when the rainfall amount was less than 2 mm. When the rainfall amount was between 2 to 4 mm and the mean rainfall intensity was below 1.6 mm·h-1, the runoff was less than 1 mm. When the rainfall exceeded 4 mm and the mean rainfall intensity was larger than 1.6 mm·h-1, the runoff would occur generally. Based on the results of the SWMM simulation, three regression equations that were applicable to regional runoff amount and rainfall factors were established. The adjustment R2 of the three equations were greater than 0.97. This indicated that the equations could reflect well the relationship between runoff and rainfall variables. The results provided the basis of calculations to plan low impact development and better reduce overflow pollution in local drainage area. It also could serve as a useful reference for runoff study in similar drainage areas.

An enzymatic assay for high-throughput screening of cytidine-producing microbial strains.

Cytidine is an industrially useful precursor for the production of antiviral compounds and a variety of industrial compounds. Interest in the microbial production of cytidine has grown recently and high-throughput screening of cytidine over-producers is an important approach in large-scale industrial production using microorganisms. An enzymatic assay for cytidine was developed combining cytidine deaminase (CDA) and indophenol method. CDA catalyzes the cleavage of cytidine to uridine and NH3, the latter of which can be accurately determined using the indophenol method. The assay was performed in 96-well plates and had a linear detection range of cytidine of 0.058-10 mM. This assay was used to determine the amount of cytidine in fermentation flasks and the results were compared with that of High Perfomance Liquid Chromatography (HPLC) method. The detection range of the CDA method is not as wide as that of the HPLC, furthermore the correlation factor of CDA method is not as high as that of HPLC. However, it was suitable for the detection of large numbers of crude samples and was applied to high-throughput screening for high cytidine-producing strains using 96-well deep-hole culture plates. This assay was proved to be simple, accurate, specific and suitable for cytidine detection and high-throughput screening of cytidine-producing strains in large numbers of samples (96 well or more).

A rapid enzymatic assay for high-throughput screening of adenosine-producing strains.

Adenosine is a major local regulator of tissue function and industrially useful as precursor for the production of medicinal nucleoside substances. High-throughput screening of adenosine overproducers is important for industrial microorganism breeding. An enzymatic assay of adenosine was developed by combined adenosine deaminase (ADA) with indophenol method. The ADA catalyzes the cleavage of adenosine to inosine and NH3 , the latter can be accurately determined by indophenol method. The assay system was optimized to deliver a good performance and could tolerate the addition of inorganic salts and many nutrition components to the assay mixtures. Adenosine could be accurately determined by this assay using 96-well microplates. Spike and recovery tests showed that this assay can accurately and reproducibly determine increases in adenosine in fermentation broth without any pretreatment to remove proteins and potentially interfering low-molecular-weight molecules. This assay was also applied to high-throughput screening for high adenosine-producing strains. The high selectivity and accuracy of the ADA assay provides rapid and high-throughput analysis of adenosine in large numbers of samples.

[Research of controlling condition for aeration stabilization pond dealing with sanitary waste of countryside].

According to research of some problems, such as the hydraulic detention time that aeration stabilization pond deals with sanitary waste of countryside, dissolved oxygen in pond during the process of aeration, the concentration distribution of sludge and different aeration periods affecting on the treatment efficiency, we can acquire good treatment efficiency and energy consumption of economy. The results indicate that under the aeration stabilization pond of this experiment, 4 d is the best hydraulic detention time with this aeration stabilization pond. Time of the discontinuous running aeration should be greater than 15 min. The concentration distribution of sludge can reach equilibrium at each point of aeration stabilization pond between 2 min and 10 min. The best aeration period of dislodging the pollutant is 0.5 h aeration/1.0 h cut-off.

[Performance of new solid carbon source materials for denitrification].

Organic carbon is needed as the electron donor in the process of reduction of nitrate transformation to nitrogen gas, which is essential for biological denitrification. Based on previous research, agriculture wastes including corncob, rice hull, rice straw and sawdust were selected as potential carbon source for denitrification. Using the static organic material of carbon source leaching kinetics test and orthogonal experiments of external factors on carbon emission process, carbon release and its mechanism of a variety of carbon materials were studied. Study showed that release process of various types of carbon source materials follows the second dynamics formula, the release curve displayed a better double-reciprocal relationship. It revealed that release amount of rice straw was the highest and sawdust was the lowest. Results showed that corncob could better be used as carbon source for denitrification. Orthogonal test indicated that the increasing of solid-liquid ratio and water temperature would lead to an enhanced release capacity of carbon, however, the change of pH had no significant effect on release capacity of carbon; according to significant degree of water temperature, pH, solid-liquid ratio impacted on the carbon release, it was sorted by solid-liquid ratio > temperature > pH.

[Nitrate removal from wastewater using rice straw as carbon source and biofilm carrier].

In this research,agriculture waste-rice straw was investigated as the sole carbon source as well as biofilm carrier to remove nitrate from wastewater in up-flow laboratory reactors. The experimental results indicated that the startup of the system was quick and a high nitrate removal efficiency was observed. The accumulation of nitrite was not observed in this process. Moreover, high nitrate concentration in the influent had a significant effect on nitrate removal efficiency. The reactor was able to accommodate a wide range of pH (6.5-8.5) and DO (1.0-3.5 mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 84 days of operation. The results showed that rice straw could be used as an economical and effective carbon source for denitrification.

Biological denitrification using corncobs as a carbon source and biofilm carrier.

In this research, agricultural waste--in particular, comcobs--was investigated for use as the sole carbon source and biofilm carrier to remove nitrate from wastewater in up-flow laboratory reactors. An artificial wastewater with a temperature range of 27 to 33 degrees C was used. Fast startup of the reactor and a high nitrate removal efficiency were observed. The highest denitrification rate of 0.203kg/(m3 x d) was achieved when flow rate and nitrate concentration were 153 L/d and 25.3 mgN/L, respectively. The accumulation of nitrite was not observed in this process. Moreover, flow rate and nitrate concentration of the influent were observed to have a significant effect on nitrate removal efficiency. A sharp decline of nitrate removal efficiency was observed when the flow rate was greater than 50 L/d. The reactor had the ability to accommodate a wide range of pH levels (6.5 to 8.5) and dissolved oxygen (1.5 mg/L to 4 mg/L). A time-dependent decrease in nitrate removal efficiency was observed after 67 days of operation. The addition of fresh corncobs brought about a rapid increase of nitrate removal efficiency. Results showed that corncobs could be used as an economical and effective carbon source for denitrification.