CFD for wastewater treatment: an overview.

Computational fluid dynamics (CFD) is a rapidly emerging field in wastewater treatment (WWT), with application to almost all unit processes. This paper provides an overview of CFD applied to a wide range of unit processes in water and WWT from hydraulic elements like flow splitting to physical, chemical and biological processes like suspended growth nutrient removal and anaerobic digestion. The paper's focus is on articulating the state of practice and research and development needs. The level of CFD's capability varies between different process units, with a high frequency of application in the areas of final sedimentation, activated sludge basin modelling and disinfection, and greater needs in primary sedimentation and anaerobic digestion. While approaches are comprehensive, generally capable of incorporating non-Newtonian fluids, multiphase systems and biokinetics, they are not broad, and further work should be done to address the diversity of process designs. Many units have not been addressed to date. Further needs are identified throughout, but common requirements include improved particle aggregation and breakup (flocculation), and improved coupling of biology and hydraulics.

A protocol for the use of computational fluid dynamics as a supportive tool for wastewater treatment plant modelling.

To date, computational fluid dynamics (CFD) models have been primarily used for evaluation of hydraulic problems at wastewater treatment plants (WWTPs). A potentially more powerful use, however, is to simulate integrated physical, chemical and/or biological processes involved in WWTP unit processes on a spatial scale and to use the gathered knowledge to accelerate improvement in plant models for everyday use, that is, design and optimized operation. Evolving improvements in computer speed and memory and improved software for implementing CFD, as well as for integrated processes, has allowed for broader usage of this tool for understanding, troubleshooting, and optimal design of WWTP unit processes. This paper proposes a protocol for an alternative use of CFD in process modelling, as a way to gain insight into complex systems leading to improved modelling approaches used in combination with the IWA activated sludge models and other kinetic models.

Familial cavernous angiomas of the brain in an Hispanic family.

We found cavernous angiomas (CA) in 10 of 22 members of a large Hispanic family. The proband had seizures, and a CA was found at surgery. He and two sisters with seizures had normal angiograms, but CT or MRI showed lesions compatible with CA. Similar abnormalities were found in two cousins with seizures and 5 of 17 asymptomatic relatives studied. MRI proved to be more sensitive than CT for identifying CA. Hispanic families appear to have a predisposition for dominantly inherited CA of the brain.

Third trimester ultrasonic presentation of infantile polycystic kidney disease.

Infantile polycystic kidney disease (Potter's Type 1) is an autosomal recessive disorder that affects the kidneys and liver. Use of ultrasound to make the diagnosis prenatally is well documented and, in fact, it is advocated as a screening device for second-trimester identification of potentially affected fetuses. The sonographic appearance is characterized by enlarged hyperechoic kidneys, enlarging fetal abdominal circumference, and oligohydramnios. It is suggested that a ratio of the kidney circumference to the abdominal circumference (KC/AC) be used as method of quantifying renal size and as a potential indicator of early kidney enlargement associated with infantile polycystic kidney disease (IPKD). We report a case of serial ultrasound examination of a pregnancy at risk for IPKD where the in utero diagnosis was not established until the third trimester.

31P and 23Na NMR studies of the structure and lability of the sodium shift reagent, bis(tripolyphosphate)dysprosium(III) ([Dy(P3O10)]7-) ion, and its decomposition in the presence of rat muscle.

The 31P NMR of aqueous [Dy(P3O10)2]7- demonstrates that it is in slow exchange with P3O5-10 on the NMR time scale. In the presence of tissue, [Dy(P3O10)2]7- decomposes to PO4 with an accompanying slow change of the tissue 23Na NMR of extracellular Na+ ion in several NMR distinguishable extracellular sites.

Correlation of ultrasound and pathologic findings in patients with epithelial carcinoma of the ovary.

The findings from preoperative diagnostic ultrasound were compared with operative and pathologic findings in patients with ovarian cancer. Twenty laparotomies were diagnostic second-look procedures and 21 were therapeutic procedures in patients with clinically evident disease. Ultrasound was more reliable in patients with clinically suspected disease, but a site by site analysis demonstrated it is insensitive for detecting prevertebral adenopathy less than 3 cm in size, thin, 1.5 cm omental plaques, 5 cm or smaller lesions involving the mesentery or bowel and peritoneal masses 2 cm or less in size. Ultrasound was most sensitive in the detection of ascites.

Chest X-rays and full lung tomograms in gynecologic malignancy.

Four-hundred-seventy-one patients with gynecologic malignancy were studied. All of these had chest x-rays at the time of staging and 323 had concurrent full lung pleuridirectional tomography performed. In no instance were pulmonary parenchymal metastases identified by tomograms when the chest x-ray was negative and tomography led to more equivocal readings than did the chest x-ray. The current study indicates that there is extremely low diagnostic yield of full lung tomography in gynecologic malignancies. Full lung tomography was poor in assessing the presence of small pleural effusions. The yield of positive chest x-ray at varying follow-up times was also examined. The yield has been expressed by site of origin of the tumor as well as by stage at initial diagnosis. Some of these yields are quite high. There is a very poor prognosis when pulmonary findings become evident, regardless of the site of origin of the tumor. More than one half of the patients who develop pulmonary abnormalities will be dead within one year.

Urologic imaging and correlation with serum laboratory determinations in staging gynecologic malignancies.

The records of 526 patients with gynecologic malignancies were reviewed to determine the correlation of urologic imaging modalities with serum renal function studies in detecting ureteral obstruction at the time of initial staging. Three hundred and forty-three of these patients had excretory urograms and 305 patients had concurrent serum urea nitrogen and creatinine determinations and 261 patients had concurrent radionuclide bone scans. Twenty-six patients had concurrent sonograms. Hydronephrosis (either unilateral or bilateral) was demonstrated at urography in 11% of patients with carcinoma of the cervix and ovary, but in only two percent of patients with carcinoma of the endometrium (the latter probably due to anatomic differences and an earlier stage of disease at the time of presentation). Serum urea nitrogen and creatinine determinations were abnormal in only 30% of the patients with urinary obstruction. Although only a small proportion of patients with hydronephrosis had bone scans and sonography, these appeared to be sensitive methods of detecting obstructions, but were more expensive than urography.

Ascites causing a false-positive radionuclide liver image.

False-positive radionuclide liver images can occur due to impingement on the liver by adjacent normal anatomic structures or adjacent pathologic masses or fluid collections. A patient with ascites in the anterior subphrenic space had an apparent "cold" lesion in the left lobe of the liver. Ultrasonography demonstrated a normal left lobe and localized the fluid collection.

Use of ultrasound in renal hypertension.

Ultrasound provides a noninvasive, sensitive, and accurate method of evaluating the kidneys in hypertensives. Although specific histologic diagnoses cannot be made, patients can be classified based on renal size and parenchymal pattern. This information is especially helpful in azotemic patients with hypertension.

Discordance in the sizing of abdominal aortic aneurysm and its significance.

Much of the confusion surrounding the repair of asymptomatic abdominal aortic aneurysms related to inaccuracies in their measurement, both preoperatively and intraoperatively. Multiple measurements of aneurysms at operation have convinced us that the largest and least variable diameter is the anteroposterior diameter measured from aortic wall anteriorly to vertebral bodies posteriorly. This AP-to-spine distance is accurately predicted by ultrasonography to within 0.3 cm. Computerized tomography does no better. plain radiography is accurate but seldom applicable. When properly estimated, aneurysm size can be accurately determined preoperatively by either ultrasonography, computerized tomography, or plain radiography, in that order of preference. Since the decision to operate on asymptomatic aneurysms is based largely on their size, accurate preoperative estimation is essential.

Radionuclide bone scan, radiographic bone survey, and alkaline phosphatase: studies of limited value in asymptomatic patients with ovarian carcinoma.

Bone scans or skeletal surveys were obtained in 104 patients with ovarian carcinoma. No metastases were identified at staging in the 43 patients with Stage I or II disease. Four patients in the entire series had osseous metastases. Three of the 40 patients with Stage III epithelial ovarian carcinoma had osseous metastases at the time of staging. All of these were Grade III lesions. One Stage I, Grade III patient demonstrated osseous metastases two years after initial diagnosis. None of the four patients with osseous metastases had an elevated alkaline phosphatase; three of the four had bone pain. Based on these results, it is suggested that radiographic bone survey and radionuclide bone scans are not indicated as screening procedures in asymptomatic patients with ovarian carcinoma.

Utility of radionuclide liver/spleen scanning and serum enzyme level in detecting hepatic metastases from ovarian carcinoma.

One hundred-five patients with ovarian carcinoma had radionuclide liver/spleen scanning done at the time of staging. Of the 105 initial scans, eight were interpreted as having hepatocellular dysfunction. Seven of these eight had abnormal liver function studies. One patient had a hepatic cyst but had elevated liver function studies. Six patients demonstrated hepatic metastases (at the time of staging). All but one of these occurred in Stage IV tumors of epithelial origin (adenocarcinoma). No hepatic metastases were demonstrated in Stage I or II tumors, and only one Stage III epithelial carcinoma had hepatic metastases. Three patients developed hepatic metastases during the course of treatment. All nine patients with hepatic metastases had abnormal concurrent liver function studies. It is suggested that screening for liver metastases in patients with ovarian carcinoma is of limited value in patients with normal liver function studies.

Intraspinal, extradural ependymoma.

Extradural ependymoma is a rare tumor arising most commonly in the soft tissues of the presacral area, less commonly in the soft tissues of the sacrococcygeal region dorsal to the sacrum, and rarely in the extradural portion of the spinal canal. The differential diagnosis varies with the location, but the natural history of the tumor is the same. If the tumor is not completely excised at surgery, it may recur. Distant metastases have been reported. A case of an extradural ependymoma arising within the spinal canal is reported with myelographic and computed tomographic findings at diagnosis and after therapy.

Utility of diagnostic imaging in the staging of gestational trophoblastic disease.

Gestational trophoblastic disease (GTD) is a group of tumors with a cure rate of 90-100% with appropriate treatment. The patients with a poor prognosis have metastatic disease involving structures other than the pelvic organs or the lungs. The medical records of 70 patients with histologically proven GTD were reviewed to determine the usefulness of diagnostic imaging modalities in the staging and follow-up of GTD. The level of chorionic gonadotropin (hCG) is more sensitive in determining the persistence of disease or its response to therapy, but is of little use in evaluating the site of metastases. Diagnostic imaging modalities are most useful in determining the presence and sites of metastases so that appropriate treatment is instituted.

Radionuclide liver and bone scanning in the evaluation of patients with endometrial carcinoma.

Staging bone scans or skeletal surveys were obtained of 97 patients with endometrial carcinoma. Of the 77 patients with Stage I or II disease, no metastases were identified at staging. Three patients in the entire series demonstrated bony metastases; all of these metastases were detectable by radionuclide bone scan and radiographic bone survey. Eighty-nine patients were examined with radionuclide liver/spleen scanning at the time of staging. Four of the 89 initial scans were interpreted as demonstrating hepatocellular disease, and all four patients had abnormal liver function studies. Only one patient demonstrated a possible hepatic metastasis at initial diagnosis. This patient also had abnormal liver function studies. Based on these results, bone surveys and radionuclide bone scans are not indicated as screening procedures in endometrial carcinoma. It is suggested that screening for liver metastases in patients with endometrial carcinoma is not warranted in patients with normal liver function studies.

Diagnostic imaging of choledochal cysts.

A review of the literature concerning the diagnostic accuracy of various imaging modalities for choledochal cysts indicates that both ultrasound and scintigraphic methods have approximately 80% accuracy. Oral cholecystography and intravenous cholangiography methods have between 60 and 80% accuracy. Ultrasound is recommended as the initial preoperative test of choice, with hepatobiliary scintigraphy or CT scanning being most useful for postoperative evaluation.

Ultrasonography in the staging of endometrial adenocarcinoma.

Adenocarcinoma of the endometrium commonly presents at an early stage and is readily diagnosed by dilatation and curettage. Ultrasound has not bee accurate in differentiating this malignant neoplasm from benign causes of uterine enlargement such as leiomyoma. In this study, the sonographic findings in 21 patients with adenocarcinoma of the endometrium were compared with the clinical and pathological findings. Although no ultrasound criteria were diagnostic of carcinoma, there were statistically significant differences in uterine shape and echo pattern between Stage I-II and Stage III-IV disease: 94% of patients with Stage I-II disease had a normal or bulbous uterus and a normal or hypoechoic parenchymal pattern, while patients with a lobular uterus and/or mixed echo pattern had Stage III-IV. The only clinical errors in staging were in cases of Stage II or III disease. Ultrasound may be helpful in pretreatment staging of more difficult cases.