M. N. Balakina

Water treatment by baromembrane methods based on ceramic membranes

The paper presents a review of the scientific and technical literature dealing with ceramic membranes that has been getting more and more common in the water treatment technology based on baromembrane methods. This review reflects advantages and disadvantages of ceramic membranes and shows that further rise in the efficiency of ceramic membranes involves the need of the scientific development of colloid-chemical foundations of their manufacture, modification, and operation, as well as the use of new technological solutions in the field of water treatment by baromembrane methods.

Water purification of nitrates by low-pressure reverse osmosis method

The paper has investigated possibilities and basic regularities of water purification of nitrates by low pressure reverse osmosis. The negative influence of chlorides and sulfates on the process characteristic have bee shown. A conclusion has bee made on expediency of using the low pressure reverse osmosis method for purifying water of nitrates.

Main regularities of reverse-osmotic water purification of phosphates

Investigated are working characteristics of reverse-osmotic membranes of low pressure ESPA-1 and TFC-75 in purifying aqueous solutions of phosphates in the range of their concentrations 10–490 mg/dm3. It is shown that at minor difference of selectivity of studied membranes with respect to phosphate–ions the specific capacity of the membrane ESPA-1noticeably exceeds such of the membrane TFC-75.

Water purification of nitrates with their deep concentration by the method of electrodialysis

The paper has shown a possibility of water purification of nitrates with their deep concentration in the form of the KNO3 salt, which is a valuable mineral fertilizer. The paper has determined working parameters of the electrodialysis process and established the negative impact of Cl− on concentration of nitrates. The article has also investigated expediency of a developed electrodialyzer concentrator for complex processing of water containing nitrates.

Processing of retentates of reverse osmosis treatment of phosphate-containing wastewater

The possibility of processing the phosphate-containing reverse osmosis retentates has been investigated. It was established that the use of NH4Cl: NH4OH mixture with 1: 4 ratio as a source of NH4+ ions and the use of magnesium chloride as a source of Mg2+ ions ensured the phosphate removal by 95.1–96.6% at the initial pH value of reaction medium equal to 10.5–11 and precipitator component ratio PO43–: NH4+: Mg2+ = 1: 1: 2.

Microfiltration treatment of domestic wastewater

The microfiltration of domestic wastewater on tubular microfilters based on clay minerals and oxide ceramics has been studied. The mechanism of the process according to which microfiltration is performed with consistent transition from filtering with gradual clogging of each pore by many particles to filtering with formation of sediment on the microfilter surface was established. A positive effect of filtering through the granular media before microfiltration was also shown.

Nitrate-containing brackish water treatment with the obtaining of ammonium fertilizers by electrodialysis

The effective purification of brackish waters of nitrates has been shown to be possible by using a special design electrodialyzer with simultaneous high concentration in a brine chamber of salts NH4NO3, NH4Cl and (NH4)2SO4 that are valuable mineral fertilizers. The brine concentration ratio increased with the rise of the current density and reached 60.0–70.6 g/dm3 under experimental conditions, while the total salt content of brine amounted to 136.7–162.5 g/dm3/ The efficiency of nitrate removal increased with the rising degree of desalination and amounted to 90% with the reduction of the total salt content of dialysate to 0.2 g/dm3.

Wastewater purification of biogenic elements

The retention capacity of the ESPA-1 membrane for nitrates, nitrites, ammonium, and phosphates has been investigated. Its application was shown to be most effective for the removal of phosphates. In this case the membrane retention capacity amounts to ∼99.8%. Nitrates are removed on conditions of up to the 90% permeate conversion in case of their initial concentration of 400 mg/dm3 and up to the 70% conversion in the interval of initial concentrations of 400–700 mg/dm3. In the case of the initial concentration of ammonium ions equal to 300 mg/dm3 and 400 mg/dm3 their removal is possible up to the 70% and 60% permeate conversions, respectively. In relation to nitrites this membrane shows a low retention capacity; however the preliminary oxidation of the latter to nitrates makes it possible to ensure their sufficiently effective removal.

Galvanocoagulation in preliminary purification of leachate of landfills of solid household wastes

We have investigated regularities of preliminary purification of leachate of disposal grounds of landfills for solid household wastes no. 1 and no. 5 of Kiev Region by the method of galvanocoagulation. It has been shown that the use of the method both independently and in combination with the process of Fenton oxidation is conducive to the improvement to the operating conditions of membranes.

Reactant purification of wastewaters of ammonium compounds

The article has investigated the process of removing ammonium ions from aqueous solutions by their deposition in the form of a valuable complex of mineral fertilizer—struvite. It has been found out that when using as a source of Mg2+ ions of magnesium oxide optimal are the initial value of the pH of the reaction medium 5.9–6.7 and the ratio NH4+: PO43–: Mg2+ = 1: 1.7: 1.7. Testing of the obtained results on the filtrate of the Kiev Dumping Ground no. 5 demonstrated that when using chosen conditions ammonium compounds are removed by more than 96%. The study of kinetic regularities of the reaction made it possible to establish that it is determined by the equation of the reaction of the third order.