Добірка наукової літератури з теми "Sewage Purification Precipitation"

In order to develop a new high-efficient but low-cost sewage treatment technology, sewage treatment experiments have been accomplished in a new type sequencing batch reactor with concrete bio-films. During experiments, simulation sewage was taken as raw water, and the operation sequence of the reactor was taken as 1.25h for water input and hypoxia, 1.25h for aeration, 0.5h for precipitation and 0.5h for water discharge successively. It has been shown by the experimental results that the reactor has optimal sewage purification effects, such as its average pollutant removal rate can arrive at about 95% for COD and BOD5, near 70% for ammonia hydrogen and about 40% for total phosphorus under the experimental condition. Main factors influencing the reactor purification effect have been discovered as pollutant volume load, ratio C/N, water temperature and amount of bio-films installed in the reactor. The mechanism of their influences has been also discussed in this paper.

The requirements for purification of the sewage will be more stringent in Sweden. For the three plants in Stockholm - Henriksdal, Bromma and Loudden the proposed limit concentrations for BOD7, total phosphorus and total nitrogen are 10, 0.3 and 15 respectively. A limit value of 0.3 mg/l of phosphorus in the effluent will require a filtration stage. In this paper results are presented from filter tests at Bromma sewage treatment plant. The tests were carried out during almost two years and included operation of different types of sand dual-media downflow filters and an upflow filter. The filters were tested with respect to sludge accumulation capacity, suspended solids removal and phosphorus removal at different operation conditions including chemical precipitation in the filters.

In this paper, phosphorus balances are calculated for the wastewater purification and sludge treatment stages for wastewater treatment plants (WWTPs) applying Enhanced Biological Phosphorus Removal (EBPR). The possible P-recovery potential is then estimated and evaluated regarding different locations along the process of wastewater purification and sludge treatment, taking the different phosphorus bonding forms into account. Caused by the more favourable bonding forms in the excess sludge as well as possibly also in the sludge ash a recovery of the phosphorus seems especially favoured for WWTPs with EBPR. The processes available for a P recycling are named, and special regard is given to the Phostrip-process, which is a possible recycling process already tested in practice. Further R&D demand consists in basic research regarding disintegration, fermentation or acidic total digestion of excess sludge followed by phosphorus precipitation including separation of the precipitates, MAP-precipitation and separation from digested sludge and on the ability to extract phosphorus and heavy metals from sewage sludge ash. These investigations are a precondition to enable purposeful process developments. At the present state the cost of recycled phosphorus earned from wastewater, sludge and ash, respectively, are a multiple higher than the costs for raw phosphate taking into account the suitable processes. Thus, up to now no phosphorus recycling with a defrayal of costs is possible. The future importance of phosphorus recycling will depend on the market price for raw phosphate, the recycling costs and, furthermore, on the general political framework.

With the continuous development of China’s modern economy and agricultural society, the discharge of rural sewage has been recognized as a major threat to the safety of the rural ecological environment. This study discussed the purification efficiency of a tower-shaped integrated ecological purification device (TIEPD)—consisting of a measuring tank, detention tank and three-stage purification unit—towards various common pollutants in rural areas during operation and tested the stability and efficiency of the TIEPD under different rural life events (fair activity days and nonfair activity days) and different precipitation intensities (light rain, moderate rain and heavy rain). The results showed that the average removal efficiencies of the TIEPD towards chemical oxygen demand, ammonia nitrogen, total nitrogen and total phosphorus were 69%, 67%, 54% and 73%, respectively. The average effluent concentration of each pollutant can meet the standard of the discharge of pollutants in China. The system exhibited good stability in removing pollutants and good ecological and economic benefits. This study provides the treatment of domestic sewage in the upper reaches of the Yangtze River and in mountainous areas of China and strengthens the prevention and control of rural nonpoint source pollution.

Today, most surface waters of Ukraine are eutrophied due to the entry into water bodies of a significant amount of nutrients – compounds of carbon, nitrogen and phosphorus. Nitrogen and phosphorus enter water bodies with wastewater, sewage from agricultural lands and livestock farms, as well as with precipitation, due to the decomposition of water biomass, aquatic vegetation and zoocenoses. In the presence of free carbon dioxide (the concentration of which depends on bicarbonate alkalinity and water pH) and at certain rates of biochemical oxygen utilization (BOD) 7.2 g of nitrogen and 1 g of phosphorus produce 115 g of algae, which decomposition then consumes 115 g of oxygen [1].

Phosphorus depletion represents a significant problem. Ash of incinerated biological sewage sludge (BSS) contains P, but the presence of heavy metals (e.g., Fe and Al) is the main issue. Based on chemical characterization by SEM-EDS, ED-XRF and ICP-OES techniques, the characteristics and P content of bottom ash (BA) and fly ash (FA) of incinerated BSS were very similar. On BA, P extraction carried out in counter- current with an S:L ratio of 1:10 and H2SO4 0.5 M led to better extraction yields than those of a similar test with H2SO4 1 M and an S:L ratio of 1:5 (93% vs. 86%). Comparing yields with H2SO4 0.5 M (S:L ratio of 1:10), the counter-current method gave better results than those of the crossflow method (93% vs. 83.9%), also improving the performance obtained with HCl in crossflow (93% vs. 89.3%). The results suggest that the purification of the acid extract from heavy metals with pH variation was impractical due to metal precipitation as phosphates. Extraction with H2SO4 and subsequent treatment with isoamyl alcohol represented the best option to extract and purify P, leading to 81% extraction yields of P with low amounts of metals.

Mechanisms for low concentrations phosphorus removal in secondary effluent were studied, and a process was developed using limestone filters (LF), submerged macrophyte oxidation ponds (SMOPs) and a subsurface vertical flow wetland (SVFW). Pilot scale experimental models were applied in series to investigate the advanced purification of total phosphorus (TP) in secondary effluent at the Chengjiang sewage treatment plant. With a total hydraulic residence time (HRT) of 82.52 h, the average effluent TP dropped to 0.17 mg L−1, meeting the standard for Class III surface waters. The major functions of the LF were adsorption and forced precipitation, with a particulate phosphorus (PP) removal of 82.93% and a total dissolved phosphorus (TDP) removal of 41.07%. Oxygen-releasing submerged macrophytes in the SMOPs resulted in maximum dissolved oxygen (DO) and pH values of 11.55 mg L−1 and 8.10, respectively. This regime provided suitable conditions for chemical precipitation of TDP, which was reduced by a further 39.29%. In the SVFW, TDP was further reduced, and the TP removal in the final effluent reached 85.08%.

Abstract Fugate water, when it enters the beginning of sewage treatment plants (STP), increases the load on the biological treatment system. Methods of purification of the STP return water are considered. A new composite composition has been developed for the reagent precipitation of ammonium and phosphates from water, which is formed as a result of thickening and dewatering of sludge. On the basis of the experimental data obtained, a technological scheme for the treatment of water formed after mechanical dewatering of excess activated sludge and sludge from the operation of treatment plants at biological wastewater treatment plants has been developed. The developed technological solution makes it possible to exclude the effect of aluminum on activated sludge and minimize the negative effect of ammonium and phosphates, with minimal construction and operating costs. The proposed cleaning method is applicable to both existing treatment facilities and newly designed ones.

On the basis of Krivoy Rog iron mining ore deposit companies (Ukraine) the complex field studies focused on the fast development of secondary landscapes in the surface of dumps after iron mining were carried out. In order to create the top layer of waste purification from household sewage was carried out sewage clearing facility silt. It is well known that breed dumps are dangerous for the environment, particularly for the surface and ground water. Overnormal concentrations of salt had been found in water samples, taken from the river Inhulets in a zone of influence breed (2.1 MPL), sulfates and carbonates (2.7 MPL), iron (2.1 MPL), chloride (1.7 MPL), magnesium (3.1 MPL). In the wells from nearest villages water is not suitable for drinking purposes and contains total sum of salts – 4.97 MPL, sulfates and carbonates – 5.16 MPL, cadmium – 3.7 MPL, lead – 1.53 MPL. Thus, the toxic heavy metals concentrations (Pb, Cd, Zn, Mn, Cu, Cr, Ni, Fe) in the fish and amphibians, as well as herbaceous plants in these areas did not exceed the permissible levels.Use of clearing facilities sludge aged from 1.5 years and more in the amount 15 kg/m2 did not lead to increased concentration of heavy metals in the top layer of dumps. Total pollution of the soil within six months after application of sludge correspond to the "permissible" level (Zc = 1.61).To assess the suitability of the silt dumps, we proposed list of indicators, which correspond to the chemical and epidemiological safety and classify as "suitable", "conditionally suitable" and "not suitable". We found that optimal conditions for formation of a new soil dumps with ratio of such indicators as "nitrogen: phosphorus: potassium" should be corresponded to the working dose 300 kg/ha by nitrogen amount. This is the maximum amount of mature silt 66.7-70 ton/ha.

A large fraction of the current cost of wastewater treatment is from the treatment and disposal of wastewater sludge. Improved design, energy efficiency, and performance of dewatering facilities could significantly decrease transport and disposal costs. Dewatering facilities are designed based on field experience, trial and error, pilot plant testing, and/or full scale testing. Design is generally time-consuming and expensive. A full-scale test typically consists_ of side-by-side operation of 4 to 5 full-scale dewatering units for several weeks to more than 6 months. Theoretical modeling of the physics of dewatering units such as the belt filter press, based on laboratory determined sludge properties, would better predict dewatering performance. This research developed a numerical computer model of the physics of gravity sedimentation. The model simulated the gravity sedimentation portion of the belt filter press. The model was developed from a physically-based numerical computer model of cake filtration by Wells (1990). As opposed to the cake filtration model, the inertial and gravity terms were retained in the gravity sedimentation model. Although in the cake filtration model, the inertial terms were shown to be negligible, according to Dixon, Souter, and Buchanan (1985), inertial effects in gravity sedimentation cannot generally be ignored. The region where inertia is important is the narrow interface between suspension and sediment. In the cake filtration model the gravity term was negligible due to the relatively large magnitude of the applied pressure; but in the gravity sedimentation model, since there was no applied pressure, it was necessary to consider the effect of gravity. _ Two final governing equations were developed - solid continuity and total momentum with continuity ("momentum"). ·The finite difference equations used a "space-staggered" mesh. The solid continuity equation was solved using an explicit formulation, with a forward difference in time and central difference in space. The "momentum" equation used a fully implicit formulation with a forward difference in time. The modeler could choose either a central difference or forward difference in space. Non-linear terms were linearized. Boundary Conditions and constitutive relationships were determined. Numerical errors in the numerical model were analyzed. The model was calibrated to known data and verified with additional data. The model was extremely sensitive to the constitutive relationships used, but relatively unaffected by the At or the use of central difference or forward difference for the spatial derivative term in the "momentum" equation. Correlations of the calibrated model to data with a low initial concentration show that the constitutive parameters approximate the data, but not very well. Model runs with low initial concentration required the addition of artificial viscosity to remain stable. The gravity term was always significant, whereas the inertial terms were many orders of magnitude less than gravity. However, the lower the initial concentration, the larger the inertial terms. In addition to the belt filter press, the model can also be applied to cake filtration and design of gravity sedimentation tanks as well.

by Li Ka Ling.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.
Includes bibliographical references (leaves 221-242).
Text in English; abstracts in English and Chinese.
by Li Ka Ling.
Acknowledgements --- p.i
Abstract --- p.ii
Contents --- p.vi
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Literature review --- p.1
Chapter 1.1.1 --- Heavy metals in our environment --- p.1
Chapter 1.1.2 --- Major source of metal pollution in Hong Kong --- p.2
Chapter 1.1.3 --- Chemistry and toxicity of copper ion --- p.9
Chapter 1.1.4 --- Removal of metal ions from effluents by precipitation --- p.12
Chapter 1.1.4.1 --- Metal ions in solution --- p.12
Chapter 1.1.4.2 --- Precipitation of metal ions --- p.13
Chapter 1.1.4.3 --- pH adjustment reagents --- p.15
Chapter 1.1.4.4 --- Precipitation of complexed metal ions --- p.19
Chapter 1.1.5 --- Other physico-chemical methods for the removal of metal ions --- p.21
Chapter 1.1.6 --- Removal of metal ions by microorganisms --- p.24
Chapter 1.1.6.1 --- Biosorption --- p.24
Chapter 1.1.6.2 --- Other mechanisms for the accumulation of metal ions --- p.28
Chapter 1.1.6.3 --- An attractive alternative for the removal and recovery of metal ions:biosorption --- p.30
Chapter 1.1.7 --- Factors affecting biosorption --- p.37
Chapter 1.1.7.1 --- Culture conditions --- p.38
Chapter 1.1.7.2 --- pH of solution --- p.39
Chapter 1.1.7.3 --- Concentration of biosorbent --- p.41
Chapter 1.1.7.4 --- Initial metal ion concentration --- p.42
Chapter 1.1.7.5 --- Presence of other cations --- p.43
Chapter 1.1.7.6 --- Presence of anions --- p.45
Chapter 1.1.8 --- Properties and uses of magnetite --- p.46
Chapter 1.1.8.1 --- Physical and chemical properties of magnetite --- p.46
Chapter 1.1.8.2 --- Use of magnetite for wastewater treatment --- p.48
Chapter 1.1.8.3 --- Immobilization of cells on magnetite for metal ion removal --- p.49
Chapter 1.2 --- Objectives of the present study --- p.54
Chapter 2. --- Materials and methods --- p.57
Chapter 2.1 --- Effects of physico-chemical factors on the precipitation of Cu2+ --- p.57
Chapter 2.1.1 --- Reagents and chemicals --- p.57
Chapter 2.1.2 --- Effects of equilibrium time --- p.59
Chapter 2.1.3 --- Effects of pH --- p.60
Chapter 2.1.4 --- Presence of anions and other cations --- p.61
Chapter 2.1.5 --- "Presence of chelating agent, EDTA" --- p.61
Chapter 2.2 --- Dissolution of metal sludge --- p.63
Chapter 2.2.1 --- Dewatering and drying of metal sludge --- p.63
Chapter 2.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.63
Chapter 2.3 --- Culture of biomass --- p.65
Chapter 2.3.1 --- Subculturing of the biomass --- p.65
Chapter 2.3.2 --- Culture media --- p.66
Chapter 2.3.3 --- Growth and preparation of the cell suspension --- p.66
Chapter 2.4 --- Immobilization of the bacterial cells on magnetites --- p.66
Chapter 2.5 --- Metal ion removal studies --- p.71
Chapter 2.5.1 --- Preparation of concentrated Cu2+ solutions --- p.71
Chapter 2.5.2 --- Removal of Cu2+ in the concentrated Cu2+ solutions by magnetite- immobilized cells --- p.74
Chapter 2.5.3 --- Effects of EDTA --- p.76
Chapter 2.5.4 --- Effects of anions --- p.77
Chapter 2.5.5 --- Effects of other cations --- p.78
Chapter 2.6 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.79
Chapter 2.7 --- Recovery of adsorbed Cu2+ from magnetite-immobilized cell --- p.79
Chapter 2.7.1 --- Desorption of Cu2+ from the immobilized cells using sulfuric acid --- p.79
Chapter 2.7.2 --- Multiple adsorption-desorption cycles --- p.80
Chapter 2.8 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.80
Chapter 2.8.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.80
Chapter 2.8.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.83
Chapter 2.9 --- Data analysis --- p.84
Chapter 3. --- Results --- p.86
Chapter 3.1 --- Effects of physical-chemical factors on the precipitation of Cu2+ --- p.86
Chapter 3.1.1 --- Effects of equilibrium time --- p.86
Chapter 3.1.2 --- Effects of pH --- p.86
Chapter 3.1.3 --- Presence of anions --- p.89
Chapter 3.1.3.1 --- Cu2+-S042- systems --- p.89
Chapter 3.1.3.2 --- Cu2+-Cl- systems --- p.89
Chapter 3.1.3.3 --- Cu2+-Cr2072- systems --- p.89
Chapter 3.1.3.4 --- Cu2+-mixed anions systems --- p.93
Chapter 3.1.4 --- Presence of other cations --- p.93
Chapter 3.1.4.1 --- Cu2+-Ni2+ systems --- p.93
Chapter 3.1.4.2 --- Cu2+-Zn2+ systems --- p.96
Chapter 3.1.4.3 --- Cu2+-Cr6+ systems --- p.96
Chapter 3.1.4.4 --- Cu2+-mixed cations systems --- p.99
Chapter 3.1.5 --- "Presence of chelating agent, EDTA" --- p.99
Chapter 3.1.5.1 --- Cu2+-EDTA4 -mixed anions systems --- p.102
Chapter 3.1.5.2 --- Cu2+-EDTA4--mixed cations systems --- p.102
Chapter 3.2 --- Dissolution of metal sludge --- p.105
Chapter 3.2.1 --- Dewatering and drying of metal sludge --- p.105
Chapter 3.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.105
Chapter 3.3 --- Removal of Cu2+ in the concentrated Cu2+ solution by magnetite- immobilized cells --- p.109
Chapter 3.4 --- Effects of EDTA on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.109
Chapter 3.4.1 --- Effects of EDTA --- p.109
Chapter 3.4.2 --- Effects of EDTA after precipitation --- p.112
Chapter 3.5 --- Effects of anions on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.120
Chapter 3.5.1 --- Effects of anions --- p.120
Chapter 3.5.2 --- Effects of anions after precipitation --- p.120
Chapter 3.5.3 --- Effects of anions in the presence of EDTA after precipitation --- p.124
Chapter 3.6 --- Effects of other cations on removal and recovery of Cu2+ by magnetite-immobilized cells --- p.129
Chapter 3.6.1 --- Effects of other cations --- p.129
Chapter 3.6.2 --- Effects of other cations after precipitation --- p.137
Chapter 3.6.3 --- Effects of other cations in the presence of EDTA after precipitation --- p.137
Chapter 3.7 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.142
Chapter 3.8 --- Multiple adsorption-desorption cycle --- p.148
Chapter 3.9 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.148
Chapter 3.9.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.148
Chapter 3.9.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.158
Chapter 4. --- Discussion --- p.167
Chapter 4.1 --- Effects of physical-chemical factors on the precipitation of Cu2+ --- p.167
Chapter 4.1.1 --- Effects of equilibrium time --- p.167
Chapter 4.1.2 --- Effects of pH --- p.168
Chapter 4.1.3 --- Presence of anions --- p.169
Chapter 4.1.4 --- Presence of other cations --- p.170
Chapter 4.1.5 --- "Presence of chelating agent, EDTA" --- p.171
Chapter 4.1.5.1 --- Presence of EDTA with anions --- p.174
Chapter 4.1.5.2 --- Presence of EDTA with other cations --- p.174
Chapter 4.2 --- Dissolution of metal sludge --- p.175
Chapter 4.2.1 --- Dewatering and drying of metal sludge --- p.175
Chapter 4.2.2 --- Dissolving of metal sludge by sulfuric acid --- p.175
Chapter 4.3 --- Metal ion removal studies --- p.176
Chapter 4.3.1 --- Selection of biomass --- p.176
Chapter 4.3.2 --- Removal of Cu2+ in the concentrated Cu2+ solution by magnetite- immobilized cells --- p.178
Chapter 4.4 --- Effects of EDTA on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.182
Chapter 4.4.1 --- Effects of EDTA --- p.182
Chapter 4.4.2 --- Effects of EDTA after precipitation --- p.184
Chapter 4.5 --- Effects of anions on removal and recovery of Cu2+ by magnetite- immobilized cells --- p.185
Chapter 4.5.1 --- Effects of anions --- p.185
Chapter 4.5.2 --- Effects of anions after precipitation --- p.188
Chapter 4.5.3 --- Effects of anions in the presence of EDTA after precipitation --- p.190
Chapter 4.6 --- Effects of other cations on removal and recovery of Cu2+ by magnetite-immobilized cells --- p.192
Chapter 4.6.1 --- Effects of other cations --- p.192
Chapter 4.6.2 --- Effects of other cations after precipitation --- p.195
Chapter 4.6.3 --- Effects of other cations in the presence of EDTA after precipitation --- p.197
Chapter 4.7 --- Maximum removal efficiency of Cu2+ by magnetite-immobilized cells --- p.198
Chapter 4.8 --- Multiple adsorption-desorption cycles --- p.199
Chapter 4.9 --- Treatment of electroplating effluent by magnetite-immobilized cells --- p.202
Chapter 4.9.1 --- Removal and recovery of Cu2+ from electroplating effluent collected from rinsing baths --- p.202
Chapter 4.9.2 --- Removal and recovery of Cu2+ from electroplating effluent collected from final collecting tank --- p.205
Chapter 5. --- Conclusion --- p.213
Chapter 6. --- Summary --- p.215
Chapter 7. --- Recommendations --- p.219
Chapter 8. --- References --- p.221