Treatment of drainage waters of domestic refuse dumps by reagent and baromembrane methods

Presented below are results of purification of drainage waters from dumps of solid domestic wastes. We studied processes of destabilization and aggregation of refuse dump drainage water impurities by the reagent method obtaining sedimentation characteristics of products of hydrolysis of iron salts and organomineral calcium complexes. We also developed a technological system for the treatment of dump drainage waters by reagent and baromembrane methods that eliminates secondary pollution of the environment by purification process wastes.     

Electroflotocoagulation treatment of drainage waters of the solid waste landfill

The process of electroflotocoagulation treatment of drainage waters from Kiev??s municipal solid waste landfill No. 5 was investigated. Unsuitability of ferrous anodes and promising results for aluminum ones to produce a coagulant were shown. To reduce aluminum consumption it is proposed to carry out acid pre-coagulation of the initial wastewater.     

Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants

Coagulation in drinking water treatment has relied upon iron (Fe) and aluminium (Al) salts throughout the last century to provide the bulk removal of contaminants from source waters containing natural organic matter (NOM). However, there is now a need for improved treatment of these waters as their quality deteriorates and water quality standards become more difficult to achieve. Alternative coagulant chemicals offer a simple and inexpensive way of doing this. In this work a novel zirconium (Zr) coagulant was compared against traditional Fe and Al coagulants. The Zr coagulant was able to provide between 46 and 150% lower dissolved organic carbon (DOC) residual in comparison to the best traditional coagulant (Fe). In addition floc properties were significantly improved with larger and stronger flocs forming when the Zr coagulant was used with the median floc sizes being 930 μm for Zr; 710 μm for Fe and 450 μm for Al. In pilot scale experiments, a similar improved NOM and particle removal was observed. The results show that when optimised for combined DOC removal and low residual turbidity, the Zr coagulant out-performed the other coagulants tested at both bench and pilot scale.     

Cleaning and reuse of the sewer-drainage waters

The article gives qualitative and quantitative characteristics of river and sewer-drainage waters of the Aral Sea basin. We investigated their chemical composition in terms of macro- and microcomponents. It was established that due to the discharge of drainage waters the contents of salts and pollutants in river waters increases. We substantiated the expediency of cleaning and reuse of drainage waters for different purposes. The paper showed the possibility of their demineralization by membrane methods.     

Automatic Coagulation Control at Water-Treatment Plants in the North-West Region of England

North West Water has evaluated several automatic coagulation control systems covering a range of raw waters and treatment facilities.
The experiences have shown that streaming-current type systems are effective in controlling coagulant dose automatically, provided that appropriate plant conditions exist. In particular, rapid fluctuations in flow or poor mixing of chemicals can lead to unstable signals. Recent investigations indicate that for some waters streaming-current voltage is sensitive to small changes in pH, and precise control of pH is therefore necessary.
The main observed benefits have been treated water of a more consistent high quality, together with improved security of service, as the systems will respond reliably and effectively over long periods. Significant savings in coagulant usage can be obtained in certain cases.     

Optimisation of combined coagulation and microfiltration for water treatment

The effect of upstream coagulant dosing for full-flow microfiltration of an upland-reservoir water has been investigated. The process, run under conditions of constant flux and pH and based on a ferric salt, is compared with a published study of another full-flow process based on alum dosing and operated at constant pressure and coagulant concentration. The current study includes data for the residual deposit remaining following backflushing by reverse flow. Results are presented in terms of the specific-cake resistance (R'o, m(-2)) as a function of pH or coagulant dose. Reasonable correlation with classical cake filtration theory was obtained, such that R' was assumed to be independent of run time and cake thickness. The following trends have been noted: The optimum pH for the alum-based system appears to be between 7.5 and 8 on the basis of cake resistance. The effect of coagulant dose between 18 and 71 microM Fe3+ is much more significant than a change in pH between 5 and 9 for the alum system: a 53-fold increase in specific flux compared with a 7-fold increase with reference to the limiting R'o values at pH 4.8 and 7.7. A low coagulant dose (0.018mM, 1.0 mg l(-1) Fe3+) appears to have a slightly detrimental effect on downstream microfiltration operation. The low coagulant doses apparently cause incomplete aggregation of colloidal particles such that internal fouling of the membrane takes place. The residual (cleaning cycle) deposit resistance followed roughly the same trend as the backflush cycle-cake resistance with coagulant concentration, but with a much reduced value (about 16 times lower, on average). An optimum coagulant dose of 0.055 mM (3.1 mg/l) Fe3+ can be identified on the basis of operational cost based on coagulant cost and cake resistance, all other aspects of the system being substantially unchanged. It is concluded that coagulation with downstream microfiltration offers a cost-effective means of removing natural organic matter, achieving a THMFP removal of around 80% at the optimum dose.     

Optimization of refuse storage systems

A deterministic inventory computer model is developed and used in selecting the optimum sizes and number of on site refuse storage systems. The majority of these systems studied are either hauled containers or open waste dumps. The optimum sizes were selected by the computer program by comparing the cost of longer refuse storage times (larger storage containers or areas and lesser frequency of refuse pickup and collection vehicles) versus shorter refuse storage times (smaller storage containers or areas and greater frequency of refuse pick-up and collection vehicles).

Optimization of refuse storage systems, resulted in efficient scheduling of refuse collection vehicles and an annual refuse collection cost savings of about US $500000.     

高分子混凝剂对污泥脱水性能的影响

城市污水处理厂每天产生大量的污泥，为了减少最终处置的污泥体积，污泥脱水是重要的处理环节。通过对不同性质的污泥进行性质分析，并选用几种高分子混凝剂对污泥进行调理试验，通过比较试验测得的污泥比阻抗值和观察试验中的矾花生成现象，以及对比滤液中的TP、COD浓度变化，确定最佳混凝剂及其投量，从而达到改善污泥脱水性能的目的。     

Optimising natural organic matter removal from low turbidity waters by controlled pH adjustment of aluminium coagulation

Effective removal of soluble natural organic matter (NOM) from low-turbidity waters can be achieved by aluminium coagulation provided due attention is paid to micro-floc formation (coagulation) and macro-floc development (flocculation). This work provides guidelines and an explanation of how pH should be controlled to maximise soluble NOM removal while at the same time making full use of pH-influencing chemicals (acid, alum, and lime). For low-turbidity waters, essential floc nucleating sites can be provided by the lime that is used for pH and alkalinity adjustment, provided that the lime is added in sufficient quantity and at a point where it retains some of its particulate nature, i.e. immediately after coagulant addition. Adjusting the pH downwards to between 4 and 5 prior to coagulant addition allows the formation of soluble NOM-aluminium complexes that link to each other, thereby forming large insoluble bridged complexes (micro-flocs), that also act as nuclei for macro-floc development (flocculation).     

Return sludge employed in enhancement of color removal in the integrally industrial wastewater treatment plant

In this study, the recirculation of chemical sludge and integrated sludge were employed for enhancement of color removal in an integrally industrial wastewater treatment plant. The jar test was conducted for simulating chemical coagulation process with different coagulants, aluminum sulfate and polyaluminum chloride (PACl), after different activated sludge systems (with air or high-purity oxygen). The results showed that with sludge recirculation the process of coagulation for the color removal has up to 35% enhancement in comparison with no sludge recirculation. Meanwhile, the color removal enhancement of coagulant aluminum sulfate was approximately 2 to 3-times the color removal enhancement of coagulant PACl at the optimum ratio of return sludge. In coagulation process with influent color of 1220 true color unit (TCU), the optimum dosage of return sludge was 3010mg/L, when coagulant PACl or aluminum sulfate was employed. In coagulation process with influent color of 536 TCU, the optimum dosages of return sludge were 2340 and 4680mg/L using PACl and aluminum sulfate, respectively.     

天津市某县高色度地下水处理试验研究

针对天津市某县地下水低浊高色的特点,应用强化混凝工艺对该地下水进行了处理,强化混凝烧杯试验表明：聚合氯化铁对该地下水的色度去除率高,强化混凝过程的最优条件是：混凝剂投加量15mg／L;静沉时间30min;300r／min搅拌1min,70r／min搅拌15min。     

不同混凝剂除磷性能的对比研究

以含磷水样为研究对象,考察了不同混凝剂(聚合氯化铝、三氯化铁及三氯化铝)的除磷效果及其影响因素,同时比较了不同碱化度PAC除磷效果的差异,明确了聚合氯化铝、三氯化铁及三氯化铝的最佳投加量和最佳pH值.搅拌条件对除磷效果的影响结果表明,混合强度的增大对除磷效果有一定的提高,混合时间以60 s为宜.     

垃圾处理工程中垃圾坝设计技术探讨

本文对城市生活垃圾处理工程中的垃圾坝 ,就其结构设计技术作了多方面的探讨通过工程实践总结 ,提出了优化设计 ,降低工程造价的 8项措施 ,供有关设计人员参考     

The Impact of Aluminum Polynuclear Hydroxo Complexes on the Impurity Coagulation in Natural Water

The effect of aluminum polynuclear hydroxo complexes on the coagulation of turbid and colored waters has been determined. The theoretical backgrounds regarding the expediency of forming mono– and polynuclear aluminum hydroxo complexes in coagulating natural waters of various composition were formulated. The joint use of aluminum sulfate and sodium hydroaluminate for the treatment of turbid and colored waters was analyzed; their efficiency was estimated in comparison with the basic coagulant. In addition, a hypothesis of the interaction mechanism of organic acids with polynuclear hydroxo complexes in the process of coagulating the colored water from surface water sources has been proposed.     

The mechanism of dissolved air flotation for potable water: basic analysis and a proposal

The principal mechanism of flotation of suspended solids in natural waters is by collision of free micro-bubbles with flocs and attachment at hydrophobic sites. Such sites are formed by adsorption of naturally-occurring organic compounds on to the precipitated alumina (or ferric “hydroxide”) derived from the coagulant added.Although effective, the current flotation process uses supersaturated water inefficiently, mainly because the average bubble size obtained is above the optimum. Unfortunately, no method is known for generating a dense cloud of micro-bubbles (< 50 μm) without adding surfactants.A more economical procedure might be based on mixing bubble-free super-saturated water with the chemically treated water, followed by conditioning in a flocculator under moderate shear. Under these conditions bubbles grow from nuclei within the flocs, which can subsequently be floated in a quiescent tank. Bench tests indicated that the method is feasible, the growth time of the bubbles being comparable with that needed for good flocculation.     

Impact of polyhexamethylene guanidine hydrochloride on the process of coagulation treatment of river waters

The paper has investigated flocculation capacity of polyhexamethylene guanidine hydrochloride during joint treatment with aluminum sulfate of the Dnieper and Desna River water in the spring period. It has been shown that additives 1–5 mg/dm³ of the matter under study during coagulation treatment of the river waters improves the process of their clarification, increases the filtrate quality in terms of main indicators and makes it possible to reduce by 10–20 mg/dm³ the dose of the coagulant. A pronounced flocculation effect manifests itself when treating the waters in question by the doses of a polymer preparation respectively 3–5 and 2–3 mg/dm³. Polyhexamethylene guanidine (without a coagulant) ensures a standardized quality of the filtrate in terms of color and turbidity only when treating weakly stained water of the Desna River. It has been found that ≥ 99% of polyhexamethylene guanidine is retained by the medium of a sand filter.     

Fate of coagulant species and conformational effects during the aggregation of a model of a humic substance with Al13 polycations

A model of a humic substance (MHS) obtained from auto-oxidation of catechol and glycine, was aggregated at pH 6 and 8 with Al(13) polycations. The fate of Al(13) coagulant species upon association with MHS functional groups was studied using solid state (27)Al Magic-angle spinning (MAS) NMR and CP-MAS (13)C NMR. Electrophoretic measurements and steady-state fluorescence spectroscopy with pyrene as a fluoroprobe, were combined to investigate structural re-organization of humic material with aluminum concentration. MAS (27)Al NMR revealed that the coagulant species are Al(13) polycations or oligomers of Al(13) units at both pHs. CP MAS (13)C spectra indicated that, at low Al concentration, hydrolyzed aluminum species bind selectively to carboxylic groups at pH 6 and to phenolic moieties at pH 8. At higher coagulant concentrations, the remaining functional groups also interact with hydrolyzed Al to yield similar CP MAS (13)C spectra in the optimum concentration range. Negative values of electrophoretic mobility were obtained at optimum coagulant concentrations even though an overall charge balance was achieved between MHS anionic charge and Al(13) cationic charge at pH 6. The polarity-sensitive fluorescence of pyrene revealed that the interaction of Al(13) coagulant species with MHS functional groups induces the formation of intramolecular hydrophobic microenvironments. Such structural changes were reversed upon further addition of Al(13) polycations.     

轻质发泡水泥保温材料的制备研究

以普通硅酸盐水泥为胶凝材料,通过化学发泡法制备密度约为220kg/m3的轻质发泡水泥保温材料,研究促凝剂、减水剂对其性能的影响并确定其最佳配合比。结果表明：偏铝酸钠可作为轻质发泡水泥保温材料的促凝剂,其最佳掺量为1.00%;聚羧酸减水剂对其力学强度、保温隔热性能及防水性能均具有提升作用。     

Cationic polymer and clay or metal oxide combinations for natural organic matter removal.

The effect of adding suspended matter in the form of clay or metal oxide when a cationic polymer was employed as the primary coagulant was found to be beneficial. The solids provide both an adsorbent for natural organic matter (NOM) and a nucleating species for precipitating the NOM-polymer complex. Metal oxides in conjunction with a cationic polymer were more promising than clay, with effectiveness in the order Fe2O3 > Fe3O4 > Al2O3 > MnO2. Magnesium oxide at a much lower dose was nearly as effective as ferric oxide, but of course raised the pH level significantly. A simpler and more convenient way of having reactive solids present was to add alum to form flocs; for one of the waters studied the alum dose could be reduced by 67% by adding 1 mg/L of polymer, to give equal or better performance than alum alone at the optimum dose.     

Isolation and characterization of coagulant extracted from Moringa oleifera seed by salt solution

It is known that M. oleifera contains a natural coagulant in the seeds. In our previous research, the method using salt water to extract the active coagulation component from M. oleifera seeds was developed and compared with the conventional method using water. In this research, the active coagulation component was purified from a NaCl solution crude extract of Moringa oleifera seeds. The active component was isolated and purified from the crude extract through a sequence of steps that included salting-out by dialysis, removal of lipids and carbohydrates by homogenization with acetone, and anion exchange. Specific coagulation activity of the active material increased up to 34 times more than the crude extract after the ion exchange. The active component was not the same as that of water extract. The molecular weight was about 3000 Da. The Lowry method and the phenol-sulfuric acid method indicated that the active component was neither protein nor polysaccharide. The optimum pH of the purified active component for coagulation of turbidity was pH 8 and above. Different from the conventional water extracts, the active component can be used for waters with low turbidity without increase in the dissolved organic carbon concentration.