Metabolic removal of phosphate from sewage effluent

Eutrophication, or fertilization, has become a major water pollution problem associated with the discharge of mineral-rich sewage eflluent. A metabolic process to remove dissolved phosphate from sewage through the action of sewage microorganisms is under development. The process, unlike other proposed solutions to the problem, would not require tertiary treatment of the sewage. Laboratory studies have produced promising data. Early reports from municipal sewage treatment plants confirm the expectation that the process may be feasible for widespread use.     

Suppression of secondary hyperparathyroidism in children with chronic renal failure by high dose phosphate binders: calcium carbonate versus aluminium hydroxide.

Secondary hyperparathyroidism was suppressed over a period of one year in 12 children with chronic renal failure by using a regimen of mild dietary phosphate restriction and high dose phosphate binders. The patients were randomised to receive either aluminium hydroxide or calcium carbonate by mouth for six months and then crossed over to the other medication. Vitamin D (dihydrotachysterol) dosage was unchanged. Serum parathyroid hormone concentrations were reduced to within the normal range, urinary cyclic adenosine monophosphate values fell, plasma phosphate concentrations decreased, and the theoretical renal phosphate threshold increased significantly. Transiliac bone biopsy findings improved in four patients with adequate suppression of parathyroid hormone concentrations, deteriorated in two patients who were not compliant, and did not change in five patients in whom initial bone disease was mild. Growth velocity improved significantly. There was no difference in the clinical response, biochemical changes, or incidence of complications during treatment with the two agents. In view of the risk of aluminium toxicity the use of high dose calcium carbonate with dietary phosphate restriction and vitamin D supplementation is recommended in the control of secondary hyperparathyroidism in children with chronic renal failure.     

Quinone profiling of bacterial communities in natural and synthetic sewage activated sludge for enhanced phosphate removal

Respiratory quinones were used as biomarkers to study bacterial community structures in activated sludge reactors used for enhanced biological phosphate removal (EBPR). We compared the quinone profiles of EBPR sludges and standard sludges, of natural sewage and synthetic sewage, and of plant scale and laboratory scale systems. Ubiquinone (Q) and menaquinone (MK) components were detected in all sludges tested at molar MK/Q ratios of 0.455 to 0.981. The differences in MK/Q ratios were much larger when we compared different wastewater sludges (i.e., raw sewage and synthetic sewage) than when we compared sludges from the EBPR and standard processes or plant scale and laboratory scale systems. In all sludges tested a Q with eight isoprene units (Q-8) was the most abundant quinone. In the MK fraction, either tetrahydrogenated MK-8 or MK-7 was the predominant type, and there was also a significant proportion of MK-6 to MK-8 in most cases. A numerical cluster analysis of the profiles showed that the sludges tested fell into two major clusters; one included all raw sewage sludges, and the other consisted of all synthetic sewage sludges, independent of the operational mode and scale of the reactors and the phosphate accumulation. These data suggested that Q-8-containing species belonging to the class Proteobacteria (i.e., species belonging to the beta subclass) were the major constituents of the bacterial populations in the EBPR sludge, as well as in standard activated sludge. Members of the class Actinobacteria (gram-positive bacteria with high DNA G+C contents) were the second most abundant group in both types of sludge. The bacterial community structures in activated sludge processes may be affected more by the nature of the influent wastewater than by the introduction of an anaerobic stage into the process or by the scale of the reactors.     

Dissolution of rabbit zona by sperm acrosomal extract: effect of calcium (1).

The acrosomal extracts from rabbit spermatozoa were more effective in dissolving the zona pellucida of the rabbit ova in the absence than in the presence of Ca2+. The extracts had high proteolytic activity but low esterolytic activity at alkaline pH in which pH effective zona hydrolysis occurred. The results suggest that acrosomal proteinases in addition to acrosin may be involved in the zona penetration.     

Genospecies ofAcinetobacter isolated from activated sludge showing enhanced removal of phosphate during pilot-scale treatment of sewage

Summary Bacteria were isolated from activated sludge showing enhanced removal of phosphate after several months operation of a pilot-scale sewage-treatment plant. Isolates were obtained by colony picking or micro-manipulation of clusters of cells and those identified genetically (i.e. by transformation) asAcinetobacter belonged mostly (78%) to a single genospecies.     

镉对固定化小球藻除磷效果的影响

采用人工配制污水进行静态模拟实验,研究了镉对被海藻酸钙凝胶包埋固定的小球藻去除磷能力的影响.结果表明:在各光照及pH条件下,镉对固定化小球藻吸收磷的效果随着实验时间的推移而变化,在实验的第一天时影响最大;总体而言,镉抑制了固定化小球藻的除磷能力,但在某些条件下镉反而提高了藻对磷的吸收;固定化处理减弱了镉对小球藻除磷能力的影响.具体的光照、pH值与镉的影响效果的关系尚待进一步探讨.     

Pretreatment of switchgrass for sugar production with the combination of sodium hydroxide and lime

Sodium hydroxide (NaOH) and lime (Ca(OH)₂) were innovatively used together in this study to improve the cost-effectiveness of alkaline pretreatment of switchgrass at ambient temperature. Based on the sugar production in enzymatic hydrolysis, the best pretreatment conditions were determined as: residence time of 6 h, NaOH loading of 0.10 g/g raw biomass, NaOH addition at the beginning, Ca(OH)₂ loading of 0.02 g/g raw biomass, and biomass wash intensity of 100 ml water/g raw biomass, at which the glucose and xylose yields were respectively 59.4% and 57.3% of the theoretical yields. The sugar yield of the biomass pretreated using the combination of 0.10 g NaOH/g raw biomass and 0.02 g Ca(OH)₂/g raw biomass was found comparable with that of the biomass pretreated using 0.20 g NaOH/g raw biomass at the same conditions, while the chemical expense was remarkably reduced due to the low cost of lime and the reduced loading of NaOH.     

The effect of various iron hydroxide concentrations on the anaerobic fermentation of sulfate-containing model sewage

The addition of iron hydroxide and iron-reducing bacteria into a fermenter for anaerobic processing of sulfate-containing sewage was shown to decrease sulfate reduction and sulfide concentration, while increasing the total organic carbon (TOC) and methane production. The effect of iron (III) in sulfate-containing sewage depended on its dose, which can be expressed as molar ratio Fe(III)/SO4(2-). Sulfide concentration increased monotonically, reaching 91 mg/l and 45 mg/l after 15 days of processing at Fe(III)/SO4(2-) ratios of 0.06 and 0.5, respectively. However, soluble sulfide production was not observed at ratios equaling 1 and 2. At ratios of 0.06, 0.5, 1, and 2, the maximum rates of TOC removal were 0.75, 1.15, 1.39, and 1.55 g TOC/g of organic matter (OM) per 1 h. Methane production rates were 0.039, 0.047, 0.064, and 0.069 mg/g OM per 1 h, with the mean relative amounts of methane in the biogas being equal to 25, 41, 55, and 62%, respectively. These data can be applied to the development of new methods of anaerobic purification of sulfate-containing sewage.     

Nature of the calcium effect in phosphate uptake by barley roots

Summary The rates of phosphate uptake of young intact plants were measured in solution at concentrations between 3.2×10^–7 M and 3.2×10^–5 M KH₂PO₄. The addition of 0.005 to 0.01M CaCl₂ increased the uptake rates to values of up to 4 times those of controls. The increases in uptake relative to the controls were most marked at the lowest phosphate concentrations. The addition of KCl also increased the uptake rates, but to a much smaller extent. The results are analyzed by the enzyme kinetic theory, and it is concluded that the uptake of phosphate at low ionic strengths is impeded by negative potentials at the root surface.The experimental results in this letter have appeared in a thesis.     

石灰氮对福寿螺的急性毒性效应

福寿螺(Pomacea canaliculata)是世界自然保护联盟认定的世界100种恶性外来入侵物种之一,在华南地区已对水稻生产造成严重危害.本研究将福寿螺按照壳高(H)分为小螺(5 mm≤H＜15 mm)、中螺(15 mm≤H＜25 mm)、大螺(25 mm≤H＜35 mm)和超大螺(35 mm≤H＜45 mm),通过室内毒性试验,探讨了化学肥料石灰氮(氰氨化钙)对不同体型福寿螺的毒性效应.结果表明:石灰氮对不同大小福寿螺毒性效应显著,尤其是对中小福寿螺具有很强的抑制和杀灭作用;石灰氮处理7 d后,最低浓度0.2 g·L-1处理造成71%死亡率,其他处理死亡率均在95%以上,其中3.0和5.0 g·L-1处理中福寿螺全部死亡;石灰氮对不同大小福寿螺的半抑制浓度(24 h)和半致死浓度(96 h)大小顺序均为小螺＜中螺＜大螺＜超大螺;石灰氮对福寿螺的抑制效应显著,其对福寿螺的平均半抑制浓度为0.08～0.39 g·L-1;1.0和5.0 g·L-1浓度的石灰氮处理24 h后,福寿螺鳃组织SOD酶活性呈极显著下降,分别为对照的41%和60%.本研究表明,石灰氮在入侵生物福寿螺的防治方面有一定应用潜力,有望成为一种新型的"杀螺肥料".     

不同植物构成的人工湿地对生活污水中氮的去除效应

测定由不同植物构成的人工湿地的氨态氮、硝态氮和亚硝态氮含量,对比不同植物对生活污水中氮的去除效率.结果表明,与不种植物的人工湿地相比,由风车草[Cyperus alternifolius L. ssp. flabelliformis (Rottb.) Kiikenth.]、香根草[Vertiveria zizanioides (Linn.) Nash]、芦苇(Phragmitas communis Trin.)和美人蕉(Canna indica Linn.)构成的人工湿地对氨态氮去除率分别提高6%、8%、11%和14%;对硝态氮去除率分别提高5%、6%、13%和9%;对亚硝态氮去除率分别提高5%、7%、10%和7%,说明种植芦苇和美人蕉的人工湿地对生活污水中的氮具有较好的去除效果.     

The primary structure of electric ray hemoglobin (Torpedo marmorata). Bohr effect and phosphate interaction

The blood of the Electric Ray contains a number of hemoglobin components. The primary structures of the alpha- and beta-chains of the main components are presented. These chains were purified by high-performance liquid chromatography, using a new buffer system. The alpha-chains consist of 141 residues, and the beta-chains of 142 residues; both are unblocked. The phylogenetic distances from human alpha- and beta-chains are 55% and 64% amino-acid exchanges, respectively. The relationship between primary structure and the lack of both a Bohr effect and any effector affinity is discussed, and interpreted on a molecular level with reference to the sequence presented. For the Bohr effect, the mutation beta 89 Asp----Lys is significant, while the mutations beta 2 His----Ser, beta 82 Lys----Asn and beta 142 His----Cys are important for the lack of effector affinity.     

Citrus leafminer (Lepidoptera: Gracillariidae) density: effect on yield of 'Tahiti' lime

The relationship between damage by citrus leafminer, Phyllocnistis citrella Stainton, and 'Tahiti' lime yield were investigated in a 15-yr-old and a 5-yr-old lime orchard. Citrus leafminer population densities were controlled by insecticide applications of abamectin plus FC 435 oil, abamectin plus FC435 oil plus imidacloprid, and methomyl. The control was not treated. To ensure adequate citrus leafminer densities, adult citrus leafminer were periodically released in the experimental plots during fall and winter. For the 15-yr-old trees, the least amount of leaf area damage occurred in the abamectin plus FC 435 oil plus imidacloprid (1.9%) and the abamectin plus FC435 oil (2.3%) treatments compared with the control treatment (10-21%). In the 5-yr-old orchard, the least amount of leaf area damaged occurred in the abamectin plus FC 435 oil plus imidacloprid (0.4%) and the imidacloprid (0.1%) treatments compared with the control (20.85%). The percentage of leaf area damaged was linearly correlated with the average number of mines per leaf, average mine days, and cumulative mine days in both orchards. In both orchards, the percentage of leaf area damaged and cumulative mine days was linearly correlated with the number of fruit per tree and total fruit weight per tree. Calculating the economic injury levels indicated that 16-23% and 18-85% of leaf area damaged caused significant yield reductions in 15-yr-old and 5-yr-old trees, respectively.     

Bone regeneration: molecular and cellular interactions with calcium phosphate ceramics

Calcium phosphate bioceramics are widely used in orthopedic and dental applications and porous scaffolds made of them are serious candidates in the field of bone tissue engineering. They have superior properties for the stimulation of bone formation and bone bonding, both related to the specific interactions of their surface with the extracellular fluids and cells, ie, ionic exchanges, superficial molecular rearrangement and cellular activity.     

Parathyroid gland hormones in the skeletal development of the ovine foetus: the effect of parathyroidectomy with calcium and phosphate infusion

It has been confirmed that the foetal parathyroid glands are important in development and that thyroparathyroidectomy (TXPTX) of the ovine foetus with thyroxine (T4) replacement leads to hypocalcaemia, retarded skeletal development, depressed calcification and rickets, relative to thyroidectomy plus T4 replacement. Histomorphometric and biochemical (urinary excretion of deoxypyridinoline) indices of bone resorption are also reduced. However, skeletal calcification can be restored to normal by longterm infusion of the TXPTX foetuses with phosphate and calcium sufficient to normalise the plasma Ca²⁺ x Pi ion product. Nevertheless, depressed resorption, reduced osteoblast numbers and delayed development persisted. The evidence suggests that the abnormally low number of resorption cavities and osteoclasts may result from the reduction in circulatory parathyroid-hormone-related protein consequent upon the removal of the foetal parathyroid glands and that this hypercalcaemic factor has a direct effect upon the process of resorption and primary trabecular remodelling of the foetal skeleton.     

The effect of inorganic phosphate on calcium influx into rat heart mitochondria

The effect of inorganic phosphate on the accumulation of Ca²⁺ by heart mitochondria has been reinvestigated. Inorganic phosphate has no effect on the initial rate of Ca²⁺ uptake supported by respiration on either ascorbate $\text{plus}$ tetramethylenephenylene diamine, pyruvate $\text{plus}$ malate, or glutamate $\text{plus}$ malate, although it does increase the final amount of Ca²⁺ accumulated; evidence suggests that the latter phenomenon requires phosphate influx via the phosphate carrier. It is concluded that the earlier reports that phosphate augments the initial rate of Ca²⁺ influx reflects an effect of phosphate on succinate oxidation, which was employed in the previous studies, rather than an Ca²⁺ transport itself.