High-salt Wastewater Research Articles

Experimental Study on Chloride Ion Removal in High-Salt Wastewater System

Chlorine is usually present in the environment in an ionic state, is highly mobile and difficult to degrade. High-chlorine wastewater can corrode buildings and affect the growth of animals and plants. Therefore, how to solve the environmental problem of high concentration of chloride ions well and effectively has drawn the intensive attention of the society. In this paper, chloride ion is removed from wastewater with the method of coprous chloride precipitation, and investigation is made on the effects of pH, temperature, amount of precipitant, titration time and reaction time on the removal efficiency of chloride ions. The results show that: when nCuSO4:nNa2SO3:nNaCl: n(ascorbic acid) =1.3:1.1:1: 0.01, and reaction pH is 3, temperature is 80 °C, titration time of sodium sulfite is 20min, reaction time after titration is 30min, the chloride ion has the optimal removal efficiency. SEM method is used for the characterization of the precipitates formed by the reaction. The results show that the experimentally produced complex cuprous chloride is irregular polyhedron with uneven particle size.

Effect of Sodium Chloride Concentration on Removal of Chemical Oxygen Demand and Ammonia from Turkey Processing Wastewater in Sand Bioreactors

HighlightsSand bioreactors can effectively treat organic matter at salt levels at least up to 13 g L-1 NaCl.Acclimation of the systems for ammonia removal can take >4 weeks.Clogging and reduction in treatment efficacy can be alleviated through resting of sand bioreactors. Abstract. The treatment of high salt (>1%) wastewater is an issue in several food industries, including meat curing, vegetable pickling, and fish processing. Novel solutions involving biological treatment of saline wastewaters are increasingly important as companies strive to minimize waste production. Sand bioreactors are a secondary treatment option that do not produce secondary sludge. The purpose of this study was to assess the feasibility of treating high salt content poultry processing wastewater with sand bioreactors. Twelve laboratory-scale sand bioreactors consisted of 14.5-cm diameter columns with three layers composed of 15 cm of gravel, 15 cm of coarse sand, and 46 cm of fine sand. The columns were dose fed at 4 cm day-1 turkey processing wastewater with 0, 6, and 13 g L-1 NaCl. Removal of chemical oxygen demand (COD) and ammonia were monitored for over an 11-month period. Each bioreactor successfully removed >90% COD and ammonia during steady state after 4 to 5 week of acclimatization. Clogging caused a decrease in treatment in three sand bioreactors after 6 to 7 months, but was alleviated with rest periods. Keywords: Ammonia removal, Clogging, High salt wastewater, Organic matter removal, Sand bioreactor, Turkey processing wastewater.

Forward osmosis membrane bioreactor using Bacillus and membrane distillation hybrid system for treating dairy wastewater

ABSTRACT Wastewater recycling is one of the best ways to alleviate water scarcity and water/wastewater pollution. The dairy industry is the largest industrial food wastewater source in many countries. In this study, we used a forward osmosis membrane bioreactor (FOMBR) and membrane distillation (MD) hybrid system to recycle dairy wastewater. And we developed a new Bacillus-FOMBR inoculated with salt-tolerant Bacillus sludge to protect against the negative effects of accumulated salt on sludge characteristics, microbial community and treatment effectiveness, and to alleviate membrane biofouling. A laboratory-scale FOMBR-MD experiment was operated for 40 days and water flux, salinity change, sludge characteristics, microbial community, nutrient removal efficiency, and FO membrane fouling were investigated. The Bacillus-FOMBR showed a small decrease in biomass concentration, and the hybrid system removed almost 100% of the contaminants. High-throughput sequencing analysis indicated that Pirellula and Hyphomicrobium species dominated the Bacillus-FOMBR, which are obliged to perform heterotrophic nitrification and aerobic denitrification. These nitrogen-removing bacteria ensured high nitrogen removal efficiency of the bioreactor. The total nitrogen (TN) concentration in the bioreactor increased and then decreased, which did not continuously increase as occurred in conventional FOMBRs. The TN removal efficiency of the bioreactor was mostly above 40% and the highest reached 79%. Besides, the Bacillus-FOMBR suffered little membrane biofouling because of the quorum quenching effect of the Bacillus species. We speculate that the Bacillus-FOMBR has potential to treat high-salt wastewater and high strength ammonia-nitrogen wastewater.

Discussion on the technical route of water pollution prevention and comprehensive utilization in thermal power plant

91 Thermal Power Plants have investigated and the problems in water management work have analyzed in this paper, combined with the policy situation. The technical route is divided in two steps. The first step for the whole plant water quality optimization, and processing, recycling use of water resources is achieved step, realize high salt wastewater minimization; The second step for the comprehensive management of waste transformation, unable to return to the high salinity wastewater, unified with the consumption and discharged into the wastewater comprehensive treatment system, through the pretreatment of softening, concentration reduction, evaporation desalting and solid waste disposal, wastewater recycling to achieve. It provides a reference for thermal power plants to explore the prevention and control of water pollution and comprehensive utilization.

A novel cold-adapted nitroreductase from Psychrobactersp. ANT206: Heterologous expression, characterization and nitrobenzene reduction capacity

Widely used in multiple industrial processes, nitro-aromatic compounds, especially nitrobenzene, in low temperature environment are considered as heavy pollutants. Among the disposal methods, the bioreduction method has attracted much attention. In this study, a novel cold-adapted nitroreductase gene (psntr) was cloned from Antarctic sea-ice bacteria Psychrobacter sp. ANT206. The psntr gene was 813 bp in length and encoded a protein with flavin mononucleotide (FMN) binding sites. Homology modeling was performed to obtain structural information such as the longer loops and reduced amount of hydrogen bonds, which might be related to the high catalytic efficiency of PsNTR at low temperature. The psntr gene was successfully cloned in cold-shock pCold I vector and transformed to the expression host Escherichia coli (E. coli) BL21 with the induction by isopropyl β-D-thiogalactoside (IPTG) at low temperature (16 °C) for 24 h. The recombinant PsNTR (rPsNTR) was purified using Ni-NTA with the specific activity of 51.59 μmol/min/mg. Interestingly, rPsNTR displayed the highest activity at 25 °C and still maintained 46.9% of the activity at 0 °C. rPsNTR also exhibited the highest activity (136.4%) at 1.0 M NaCl with incredible salt tolerance. The kinetic parameters and substrates specificity analysis demonstrated that rPsNTR could reduce various nitro-aromatic compounds. Moreover, the result of the reduction capability revealed that the recombinant E. coli exhibited a maximum nitrobenzene reduction rate of 3.03 mM/h at 16 °C. These findings revealed that the characteristics of rPsNTR might make it an excellent candidate for the bioreduction of various nitro-aromatic compounds in the low temperature and high-salt wastewater.

Comparative transcriptome analysis of salt tolerance mechanism of Meyerozyma guilliermondii W2 under NaCl stress.

A high-salt-tolerant strain, Meyerozyma guilliermondii, has been isolated from activated sludge which has a great effect in the treatment of high-salt wastewater. To identify the salt tolerance mechanism of the strain, transcriptome sequencing and fluorescence quantitative PCR were used to analyse and compare the thallus, which were growing in the salt-free, low-salt (4%), and high-salt (16%) YPD media for 48h, respectively, and then the change of intracellular and extracellular glycerol was determined. The results showed that 8220 unigenes were obtained from the sequencing data after de novo splicing, among which 6334 genes had annotation information in the SwissProt library. With salt-free as reference, there were 1135 unigenes that differentially expressed under low-salt stress and 1948 unigenes were differentially expressed under high-salt stress. With low salt as reference, 3056 unigenes were differentially expressed under high-salt stress. The fluorescence quantification results of the six candidate genes selected in this study were consistent with the transcriptome data. Under high-salt stress, the intracellular glycerol of M. guilliermondii reached a maximum value at about 10min, then decreased quickly and tended to be stable. This study provided valuable data for the next study of salt tolerance of M. guilliermondii, and also contributed to the functional study of yeast salt tolerance genes.

Effect of Brine Acidification on Fermentation Microbiota, Chemistry, and Texture Quality of Cucumbers Fermented in Calcium or Sodium Chloride Brines.

Commercial fermentation for bulk preservation of cucumbers relies on natural microbiota and approximately 1 M sodium chloride (NaCl) brines, resulting in large volumes of high-salt wastewater. An alternative process utilizing 0.1 M calcium chloride (CaCl2 ) as the only salt was developed to eliminate NaCl from fermentation brines for reduced environmental impact. This study determined the effect of brine acidification on the fermentation microbiota and texture quality of cucumbers fermented in CaCl2 brines. Cucumber fermentations were conducted in sealed glass jars for six independent lots of cucumbers in a randomized complete block design with a full-factorial treatment structure for brine acidification (acetic acid, hydrochloric acid, or nonacidified) and brining salt (1 M NaCl or 0.1 M CaCl2 ). Enterobacteriaceae spp. survived longer and were >1 log colony forming units/mL higher in fermenting cucumbers than in brines. Addition of 25 mM acetic acid to fermentation brines (but not the addition of hydrochloric acid at the same pH) reduced Enterobacteriaceae spp. in brines and cucumbers (P < 0.002) during the initiation of fermentation for both brining salts. However, acidification had no effect on texture quality of fermented cucumbers (P = 0.8235). Despite differences in early fermentation microbiota, fermentation of cucumbers in calcium chloride brines under controlled conditions, with or without acidification, resulted in high retention of tissue firmness. These results differ from fermentations in a commercial setting initiated in brines of neutral pH, indicating that production variables, such as air exposure, interact with brining in CaCl2 to negatively affect the texture quality of fermented cucumbers. PRACTICAL APPLICATION: This study examined the effects of initial brine acidification on the course of lactic acid fermentation and resulting texture quality of cucumbers fermented in calcium or sodium salt brines. Fermentation brines containing acetic acid (the acid in vinegar) reduced the pH of the cucumber and the soil-associated Enterobacteriaceae spp. most rapidly, and favored the conversion of sugars to lactic acid. Interestingly, the texture quality was not affected by brine acidification, and all cucumbers fermented in calcium brines in the absence of air retained their firmness during fermentation and bulk storage.

Characterization of the genome from Geobacter anodireducens, a strain with enhanced current production in bioelectrochemical systems.

Geobacter anodireducens is unique in that it can generate high current densities in bioelectrochemical systems (BES) operating under high salt conditions. This ability is important for the development of BES treating high salt wastewater and microbial desalination cells. Therefore, the genome of G. anodireducens was characterized to identify proteins that might allow this strain to survive in high salt BES. Comparison to other Geobacter species revealed that 81 of its 87 c-type cytochromes had homologs in G. soli and G. sulfurreducens. Genes coding for many extracellular electron transfer proteins were also detected, including the outer membrane c-type cytochromes OmcS and OmcZ and the soluble c-type cytochrome PgcA. G. anodireducens also appears to have numerous membrane complexes involved in the translocation of protons and sodium ions and channels that provide protection against osmotic shock. In addition, it has more DNA repair genes than most Geobacter species, suggesting that it might be able to more rapidly repair DNA damage caused in high salt and low pH anode environments. Although this genomic analysis provides invaluable insight into mechanisms used by G. anodireducens to survive in high salt BES, genetic, transcriptomic, and proteomic studies will need to be done to validate their roles.

Applying facilely synthesized CuO/CeO2 photocatalyst to accelerate methylene blue degradation in hypersaline wastewater

Textile and dye effluents have strong color, unstable pH and COD, a lot of inorganic salt, and high biotoxicity. It is difficult and inefficient to remove dyes from high‐saline wastewater by traditional methods. In this study, a simple synthetic CuO/CeO2 photocatalyst is used to achieve high efficiency photodegradation of methylene blue in high salt wastewater. The p‐type CuO/n‐type CeO2 heterojunction photocatalyst is synthesized by a modified hydrothermal‐calcination method. The XRD and XPS reveal the successful synthesis of CuO/CeO2 composite. The SEM and TEM images show that the sample consists of large amounts of well‐dispersed CuO nanosphere loading on the CeO2 layers. DRS exhibits the absorption band (about 510 nm) and the band gap energy (2.43 eV) of the CuO/CeO2 composite. Compared with pure CuO, CeO2, and TiO2 (P25), the prepared CuO/CeO2 can increase the mineralization rate of MB by 18.19%~33.74%. More than 80% of MB can be effectively removed in the wastewater containing 5~80 g/L NaCl with a wide pH value range of 2.11~9.02, and the degradation processes follow the pseudofirst‐order reaction kinetics. Active species trapping experiments confirm that the degradation of methylene blue is mainly attributed to hydroxyl radical; besides, O2▪− and hole (h+) also play important roles. Chlorine ions have dual effects in photocatalytic reactions. This work could provide a new approach to construct new heterojunction photocatalysts and a deeper insight for the treatment of hypersaline dye wastewater.

Isolation and Nitrogen Removal Characteristics of Salt-tolerant Heterotrophic Nitrification and Aerobic Denitrification Bacteria Zobellella sp. B307

A heterotrophic nitrification and aerobic denitrification strain, B307, was isolated from the sediment of Jiaozhou Bay. The strain was identified by 16S rRNA sequence analysis, and its optimization condition and salt-tolerance characteristics were studied by single factor experiment. The denitrification effect in single or mixed nitrogen sources was investigated under optimum conditions. The results allowed the strain to be identified as Zobellella sp., based on 16S rRNA sequence analysis. The best carbon source was sodium succinate, and the optimum C/N was 5, the optimal initial pH was 9, and the optimal temperature was 35-40℃ respectively. After 12 hours, the NH4+-N and the NO3--N removal efficiencies were 98.35% and 99.75% in a mixed nitrogen source system. The removal efficiencies for NH4+-N and NO3--N were 97.67% and 94.39% within 24 hours when salinity was 75 g·L-1. The strain has highly efficient heterotrophic nitrification-aerobic denitrification ability and strong salt tolerance, which demonstrated that the strain has potential for extensive application for nitrogen removal in high salt wastewater.

Degradation of Phenol in Water Using a Novel Gas-Liquid Two-Phase Dielectric Barrier Discharge Plasma Reactor

Phenol is toxic to human and persistent in the environment. Traditional treatment methods have the disadvantages of long treatment time, large amount of agents, and secondary pollution. In this study, a novel gas-liquid two-phase dielectric barrier discharge reactor was designed to remove phenol in aqueous solution. The effects of operating conditions (applied voltage, discharge spacing, pH, and conductivity), different water matrix (deionized water, groundwater, surface water, tap water), and inorganic ions were investigated. Moreover, the reaction mechanisms and the possible degradation pathway were proposed. The removal efficiency of phenol achieved 95.5% under the optimal operating conditions (discharge voltage of 17.6 kV, discharge gap of 1 mm, air flow rate of 60 mL min−1) coupling with H2O2 at 10 mM. The presence of different concentrations of inorganic ions (0.1, 1, 10, and 20 mM) could inhibit the phenol removal efficiencies. Specially, Cl− had different effects on phenol removal efficiency. The inhibition of Cl− on phenol removal was weakened when Cl− concentration was greater than 1 mM, which allows the technology that has certain advantages in treating high-salt wastewater containing high chloride concentration. In addition, ˙OH was verified as the main active species in phenol removal. The possible degradation pathway was proposed according to theoretical calculation and GC-MS measurement.

Green recovery of hazardous acetonitrile from high-salt chemical wastewater by pervaporation

Abstract Acetonitrile in high-salt wastewater is not only a pollutant and a toxic and hazardous problem but also an inefficient use of resources. Acetonitrile in high-salt wastewater is refractory to and difficult for wastewater treatment. In this work, the separation and recovery of hazardous acetonitrile from high-salt aqueous streams by pervaporation were investigated, and the operating process conditions were evaluated. The separation of acetonitrile from wastewater was conducted using a polydimethylsiloxane (PDMS) membrane and was promoted by high concentrations of acetonitrile and high temperatures. The activation energy for the permeation of acetonitrile and water through the membrane indicated that the pervaporation of acetonitrile is more highly temperature dependent than that of water. The maximum permeate flux achieved was 353 g/m2h, and the highest concentrations of acetonitrile in the permeate were found to be greater than 47%. The results also showed that high salt in wastewater had a positive effect on the pervaporation performance and the separation factor. The process provides a paradigm change toward viewing the acetonitrile in wastewater as a resource to be recovered rather than waste to be treated, and thus, clean production can be realized.

Characteristics of Denitrification Inhibiting Sulfate Reducing Process

In this study, a set of two-stage UASB reactor was used to study the characteristics of denitrification inhibiting sulfate reduction in oil field gathering and transportation system and some high salt wastewater, and the characteristics of granular sludge and microbial characteristics were studied after the stable operation of the process. The results showed that the addition of NaNO2 increased the number of denitrifying bacteria (DNB) from 7.0×103 CFU·(100 mL)-1 to 7.3×105 CFU·(100 mL)-1 and remained stable in the process from start to mature. The competitive inhibition caused by DNB decreased the number of SRB from 8.0×105 CFU·(100 mL)-1 to 7.6×104 CFU·(100 mL)-1. Meanwhile, the sulfate reduction was inhibited, and the inhibition rate increased and finally stabilized to 82%. The study on mass ratio of microbial mass to nitrite effecting on denitrification efficiency showed that the inhibition rate of S2- was the highest, reaching 92%, when the mass ratio was 1200. The inhibition rate of the process could remain at about 92%, with good stability. The particle size and sedimentation rate of granular sludge were measured to determine whether the process conditions were favorable for the formation of granular sludge. The study showed that the denitrifying granular sludge formed was brown, basically ellipsoidal and spherical, with smooth surface and high density. Before the denitrification inhibition, the particle size of granular sludge was 1.0-1.4 mm and the average diameter was 1.17 mm, and after denitrification inhibition, the particle size distribution was 1.2-1.6 mm, the average particle size was 1.21 mm, which indicated that the denitrification inhibition increased the size of granular sludge. The average sedimentation velocity of denitrifying granular sludge was 47.6 m·h-1, which revealed the good settling performance of the granular sludge. The results of PCR-DGGE analysis showed that the denitrification inhibition reduced the number of microbial species from 18 to 14 and the number of dominant species decreased from 4 to 3, indicating the decreasing microbial diversity. The similarity of microbial population before and after nitrification was 62.6% and the population structure changed greatly from SRB to DNB. The number of dominant SRB species decreased from 4 to 2 after denitrification inhibition and the abundance of every species decreased obviously. The main functional bacterial species of the inhibition process was uncultured Sulfurimonas sp., which is a kind of autotrophic denitrifying bacteria. It dominated and competed with SRB for electrons, inhibiting the sulfate reduction and the production of sulfide.

Study of Composite Adsorbent Synthesis and Characterization for the Removal of Cs in the High-salt and High-radioactive Wastewater

For the removal of cesium (Cs) from high radioactive/high salt-laden liquid waste, this study synthesized a highly efficient composite adsorbent (potassium cobalt ferrocyanide (PCFC)-loaded chabazite (CHA)) and evaluated its applicability. The composite adsorbent used CHA, which could accommodate Cs as well as other molecules, as a supporting material and was synthesized by immobilizing the PCFC in the pores of CHA through stepwise impregnation/precipitation with CoCl2 and K4Fe (CN)6 solutions. When CHA, with average particle size of more than 10 ㎛, is used in synthesizing the composite adsorbent, the PCFC particles were immobilized in a stable form. Also, the physical stability of the composite adsorbent was improved by optimizing the washing methodology to increase the purity of the composite adsorbent during the synthesis. The composite adsorbent obtained from the optimal synthesis showed a high adsorption rate of Cs in both fresh water (salt-free condition) and seawater (high-salt condition), and had a relatively high value of distribution coefficient (larger than 104 mL·g-1) regardless of the salt concentration. Therefore, the composite adsorbent synthesized in this study is an optimized material considering both the high selectivity of PCFC on Cs and the physical stability of CHA. It is proved that this composite adsorbent can remove rapidly Cs contained in high radioactive/high salt-laden liquid waste with high efficiency.

Seawater desalination with solar-energy-integrated vacuum membrane distillation system

This study designed and tested a novel type of solar-energy-integrated vacuum membrane distillation (VMD) system for seawater desalination under actual environmental conditions in Wuhan, China. The system consists of eight parts: a seawater tank, solar collector, solar cooker, inclined VMD evaporator, circulating water vacuum pump, heat exchanger, fresh water tank, and brine tank. Natural seawater was used as feed and a hydrophobic hollow-fiber membrane module was used to improve seawater desalination. The experiment was conducted during a typical summer day. Results showed that when the highest ambient temperature was 33 °C, the maximum value of the average solar intensity was 1,080 W/m2. The system was able to generate 36 kg (per m2 membrane module) distilled fresh water during 1 day (7:00 am until 6:00 pm), the retention rate was between 99.67 and 99.987%, and electrical conductivity was between 0.00276 and 0.0673 mS/cm. The average salt rejection was over 90%. The proposed VMD system shows favorable potential application in desalination of brackish waters or high-salt wastewater treatment, as well.

Novel application of nanozeolite for radioactive cesium removal from high-salt wastewater

Finding a striking peculiarity of nanomaterials and evaluating its feasibility for practical use are interesting topics of research. We investigated the application of nanozeolite's outstanding reactivity for a rapid and effective method for radioactive cesium removal in the wastewater generated from nuclear power plant accident, as a new concept. Extremely fast removal of cesium, even without stirring, was achieved by the nanozeolite at efficiencies never observed with bulk materials. The nanozeolite reached an adsorption equilibrium state within 1 min. Cesium adsorption by nanozeolite was demonstrated at reaction rates of orders of magnitude higher than that of larger zeolite phases. This observation was strongly supported by the positive correlation between the rate constant ratio (k2,bulk/k2,nano) and the initial Cs concentrations with a correlation coefficient (R2) of 0.99. A potential drawback of a nanoadsorbent is the difficulty of particle settling and separation because of its high dispersivity in solution. However, our results also demonstrated that the nanozeolite could be easily precipitated from the high-salt solution with ferric flocculant. The flocculation index reached a steady state within 10 min. A series of our experimental results met the goal of rapid processing in the case of emergency by applying the well-suited nanozeolite adsorption and flocculation.

An ecological new approach for treating Cr(VI)-containing industrial wastewater: Photochemical reduction

An ecological new approach for photochemical reduction of Cr(VI) in aqueous solution by adding into water-soluble copolymer, polyethylene glycol (PEG), was investigated. Various influences including light intensity, initial solution pH value, PEG molecular weight and initial concentration ratio of PEG to Cr(VI) on photochemical reduction of Cr(VI) were discussed, and a possible reaction mechanism was proposed. Experimental results revealed that Cr(VI) could be reduced to Cr(III) by PEG under sunlight irradiation. The photo-reduction rate of Cr(VI) increased with the decrease of solution pH and PEG molecular weight, but increased with the light intensity. The reduction percentage of Cr(VI) increased with the initial concentration ratio of PEG to Cr(VI). When the initial solution pH value was below 3.0, almost all of Cr(VI) was completely reduced to Cr(III) within 20 min of 50 × 103 lux solar irradiation in the presence of PEG. After photo-reduction, PEG and Cr(III) in aqueous solutions could be recovered by adding into a high-concentrated Na2SO4 aqueous solution to induce the formation of a stable PEG-based aqueous biphasic system. By doing so, Na2SO4 in aqueous solution could also be removed. The present work highlights a promising new route for treating the industrial wastewater containing toxic Cr(VI) ions by adding into environmental-friendly PEG for photo-reduction of Cr(VI) to Cr(III), and then salting-out recovery of PEG and removal of Cr(III) in wastewater by adding into another high-salt wastewater, so that the high-salt wastewater could also be treated.

Graphene-oxide modified polyvinyl-alcohol as microbial carrier to improve high salt wastewater treatment

This work discussed the preparation and characterization of graphene oxide (GO) modified polyvinyl alcohol (PVA) for bacteria immobilization to enhance the biodegrdation efficiency of saline organic wastewater. GO–PVA material has lamellar structure with higher surface area to support bacterial growth and high salinity tolerance. It significantly stimulated the bacterial population by 1.4 times from 2.07×103CFU/mL to 5.04×103CFU/mL, and the microbial structure was also improved for salinity tolerance. Acinetobacter, Pseudomonas and Thermophilic hydrogen bacilli were enriched inside GO–PVA materials for glucose biodegradation. Compared to the CODCr removal efficiency with only PVA as the carrier (52.8%), GO–PVA material had better degradation performance (62.8%). It is proved as a good candidate for bioaugmentation to improve biodegradation efficiency in hypersaline organic wastewater.

Influence of High-Salinity Impact Load on an Integrated Sync Contact Oxidation Process

To solve the problem of high-salt ballast wastewater treatment, biological contact oxidation process by combined packing used to simulate the experimental study. When dissolved oxygen is 5 to 6, water temperature is 18 ~ 20 °C, pH is 7~8 and hydraulic retention time is 48h, the Influence of salinity dips and swells process on sludge treatment system and its effects were investigated. The results showed that salinity shock loads on the system less affected COD removal, after 3-5 days short adaptability run, the system became able to restore effluent water stability. The influence of Salinity swells process on AOB, NOB and denitrifying bacteria was greater than a dip .Salinity plunged produced smaller impact on the total nitrogen removal, while in the salinity swells TN removal reduced from 70.7% to 42%.

Application and Influencing Factors of Complex Microbial Inoculants in Wastewater Treatment

Complex microbial inoculants are highly effective compound bacteria which are widely used in the removal of pollutants, such as organic matter, nitrogen and phosphorus in the paper, printing and dyeing, petroleum and high-salt wastewater. The development of complex microbial inoculants was introduced in this paper, especially their application and influence factors in wastewater treatment. Finally we put forward current problems and development prospects of complex microbial inoculants.