Utilization In Wastewater Treatment Research Articles

Biochemical response of cyanobacterial species to trivalent chromium stress

Toxic metal reclamation from wastewaters using biotechnology has focused attention on a variety of microbes and one such potential group is Cyanobacteria. Effluent water discharged from tanneries support the growth of many microbial species including Cyanobacteria. In the present study an attempt has been made to study the growth response of six cyanobacterial species to trivalent chromium (Cr3+), before being used for phycoremediation. The studies relate to biochemical response of these species to different concentrations of Cr3+ under stress and their metal binding capacity in the media vis-à-vis its uptake in lab conditions. The results indicated that Aulosira sp. A287 exhibited high tolerance to Cr3+ (750mgL−1) in the media although the maximum uptake was observed in Spirulina platensis (214mgg−1). The biochemical analysis showed quantitative reduction in chlorophyll-a in S. platensis, Oscillatoria sp. A280 and Lyngbya sp. with increasing Cr3+ dosage, whereas the rest of the species showed decreasing trend. This change in protein profile was validated using SDS-PAGE. However, total carbohydrate increased in all the species tested when compared to controls. Among the species studied the response of S. platensis to Cr3+ stress was higher. The present study demonstrates the capability of cyanobacteria to withstand Cr3+ stress and their possible utilization in wastewater treatment.

Fate and behavior of extended-spectrum β-lactamase-producing genes in municipal sewage treatment plants

Extended-spectrum β-lactamases (ESBLs) have the capability of hydrolyzing a variety of the newer β-lactam antibiotics, including the third-generation cephalosporins and monobactams known as a rapidly evolving group of ESBLs. The purpose of this study was to investigate the occurrence and fate of β-lactamase producing genes (CTX-M type 1, type2, CTX-M probe for all groups except CTX-M-1, and TEM, SHV, OXA) through wastewater treatment utilities. β-lactamase producing genes in influent, digested sludge, activated sludge, and disinfected effluent were monitored. The results showed that influent contained high level of all target genes, and all CTX-M types, SHV, and OXA gene decreased significantly in biological treatment process such as activated sludge process and anaerobic digestion, however, TEM type was not effectively eliminated. Possibly, host microbes of TEM could be most resistant in target genes or to some extent gene transfer occurred in wastewater treatment processes. All target genes were significantly reduced during disinfection. Consequently, wastewater treatment process apparently reduced host microbes carrying β-lactamase producing genes effectively, although they are selectively removed in biological processes. In addition, the significant reduction during disinfection was shown, although slightly differences of removal efficiency were observed in resistance.

Comparing three methods for photosynthetic bacteria separation and recycling during wastewater treatment

Photosynthetic bacteria (PSB) wastewater treatment technology can simultaneously treat wastewater and produce valuable materials. However, PSB are typically difficult to collect from wastewater, which limits their utilization in wastewater treatment and resource recovery. In this study, three different methods (e.g. immobilization, coagulation and membrane separation) were investigated and compared for PSB collection to recover bioresources. A strain of PSB, Z08 (Rhodobacter sphaeroides) was used. Results showed that PSB hardly attached to the seven support materials tested during immobilization. Aluminium polychloride was shown to be effective at PSB separation via coagulation at a dosage of 5,000 mg/L; however, coagulants might cause the second pollution. Also, the membrane was effective at Z08 collection. Ninety-nine per cent of PSB was collected from water; this PSB liquid was then concentrated by a factor of 12.4, and the water production ratio reached 93.0%. The optimal Z08 dosage was 1,682.1 mg/L, which generated 165,396.0 mg/L of biomass within a 50 h water cycle. Compared with activated sludge, the water cycle that combines the PSB and the membrane can function up to 60 min with an initial PSB concentration of 10,000 mg/L, which will mitigate membrane fouling and achieve bioresource recovery.

Adsorption of 2,4-Dichlorophenol and Rhodamine-B from Aqueous Solutions onto Activated Carbon Derived from Phragmites Australis

This study investigates the potential use of activated carbon prepared from Phragmites Australis for the removal of 2,4-dichlorophenol (DCP) and Rhodamine-B (RB) from aqueous solutions. P. Australis activated carbon (PAAC), a new adsorbent, was prepared from P. Australis by H3PO4 activation. Batch adsorption studies were conducted to evaluate the effect of various parameters such as pH, adsorbent dose, contact time and initial 2,4-DCP and RB concentration. Accordingly, the activated carbon developed in this study is effective and practical for utilization in wastewater treatment for 2,4-DCP and RB removal.

Modification of Fly Ash and its Application State Research in Wastewater Treatment

Coal fly ashes are a coal combustion product at high temperature. With a certain porous structure and large specific surface area, they have certain adsorption capacities and can be used as the materials for watewater treatment.But limited by the adsorption properties, the raw coal fly ashes have a very low pollutant removal efficiency, and can not meet the practical requirements of wastewater treatment. Therefore, researches now focus on the coal coal fly ashes modification, including increasing the active components in them, enlarging the specific surface area to improve their performance, and to enhance their wastewater treatment effects.Aiming at providing some references of their integrated utilization in wastewater treatment, the modification methods and application status of the coal coal fly ashes are summarized.

Removal of silver nanoparticles in simulated wastewater treatment processes and its impact on COD and NH4 reduction

The increasing utilization of silver nanoparticles in industrial and consumer products has raised concern to wastewater treatment utilities due to its antimicrobial activity. In this work, the removal of citrate stabilized silver nanoparticles (Ag-NPs) during the wastewater treatment processes and its impact on treatment performance were examined. During simulated primary clarification, over 90% of the Ag-NPs remained in the wastewater, indicating that the majority of silver nanoparticles in sewage would enter the subsequent treatment units. During sequencing batch reactor processes, silver nanoparticles were effectively removed in each cycle throughout the 15-d experimental duration. Continuous input of silver nanoparticles into the wastewater did not significantly alter chemical oxygen demand (COD) removal. NH4 removal was reduced at the beginning of the SBR experiment but quickly recovered at the later stage of the experiment. This study demonstrated that in the near future it is unlikely that citrate-stabilized Ag-NPs released into sewage will cause significant adversary effects on the COD and NH4 removal of activated sludge processes in municipal wastewater treatment plants.

From Grease to Green: Two Case Studies of FOG Receiving, Co-Digestion and Combined Heat and Power Generation

From Grease to Green: Two Case Studies of FOG Receiving, Co-Digestion and Combined Heat and Power GenerationIncreasingly, wastewater treatment utilities are considering the dual benefits associated with fats, oils, and grease (FOG) receiving. Receiving this material can help to address the removal of a problematic material from the collection system by facilitating periodic grease trap cleaning and maintenance at food service establishments (FSEs) in their service areas. Through co-digestion of this...Author(s)Matthew P. Van HorneTheresa BrutonScott HardyC. Michael BullardHunter LongSourceProceedings of the Water Environment FederationSubjectSession 6: Biogas Use and Methane Emmission as a Greenhouse Gas (GHG)Document typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:6L.516;1-DOI10.2175/193864711802836238Volume / Issue2011 / 6Content sourceEnergy ConferenceFirst / last page(s)516 - 532Copyright2011Word count213Subject keywordsFOGfats oils and greaseco-digestioncombined heat and powerdigester gasanaerobic digestion

Release of antibiotic resistant bacteria and genes in the effluent and biosolids of five wastewater utilities in Michigan

The purpose of this study was to quantify the occurrence and release of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) into the environment through the effluent and biosolids of different wastewater treatment utilities including an MBR (Membrane Biological Reactor) utility, conventional utilities (Activated Sludge, Oxidative Ditch and Rotatory Biological Contactors-RBCs) and multiple sludge treatment processes (Dewatering, Gravity Thickening, Anaerobic Digestion and Lime Stabilization). Samples of raw wastewater, pre- and post-disinfected effluents, and biosolids were monitored for tetracycline resistant genes (tetW and tetO) and sulfonamide resistant gene (Sul-I) and tetracycline and sulfonamide resistant bacteria. ARGs and ARB concentrations in the final effluent were found to be in the range of ND(non-detectable)-2.33 × 106 copies/100 mL and 5.00 × 102–6.10 × 105 CFU/100 mL respectively. Concentrations of ARGs (tetW and tetO) and 16s rRNA gene in the MBR effluent were observed to be 1–3 log less, compared to conventional treatment utilities. Significantly higher removals of ARGs and ARB were observed in the MBR facility (range of removal: 2.57–7.06 logs) compared to that in conventional treatment plants (range of removal: 2.37–4.56 logs) (p < 0.05). Disinfection (Chlorination and UV) processes did not contribute in significant reduction of ARGs and ARB (p > 0.05). In biosolids, ARGs and ARB concentrations were found to be in the range of 5.61 × 106–4.32 × 109 copies/g and 3.17 × 104–1.85 × 109 CFU/g, respectively. Significant differences (p < 0.05) were observed in concentrations of ARGs (except tetW) and ARB between the advanced biosolid treatment methods (i.e., anaerobic digestion and lime stabilization) and the conventional dewatering and gravity thickening methods.

MODELLING OF CHLORIDE INFLUENCE UPON ACTIVATED SLUDGE COMMUNITY GROWTH/CHLORIDŲ ĮTAKOS VEIKLIOJO DUMBLO BIOCENOZĖS DINAMIKAI MODELIAVIMAS/МОДЕЛИРОВАНИЕ ВЛИЯНИЯ ХЛОРИДОВ НА ДИНАМИКУ БИОЦЕНОЗА АКТИВНОГО ИЛА

Growth kinetics, i.e. the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in the modelling of activated sludge community growth. The above‐described conventional growth kinetics derived from single‐substrate‐controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in wastewater treatment. After technological processes various mineral substances, such as chlorides, get into water bodies. These substances are not removed from wastewater by the biological treatment method. The purpose of this study is to determine the concentrations of chlorides, investigate the influence of enzyme preparations upon wastewater treatment quality during biological process modelling. Kinetics of microbial growth was designed using the model of Monad. To analyse the chloride influence on the biooxidation process a series of laboratory tests was carried out: biochemical oxygen consumption (BOD), activated sludge concentration and other indexes. It is found experimentally that a 400 mg/l concentration of chlorides disarranges the activity of microorganisms and activated sludge is no longer suitable for biological treatment. Also, we investigated the effect of enzyme preparation on effluence on sewage treatment. As chloride concentrations are increased in a tank without an enzyme, bacterial spores contained in the enzyme preparation produce a renewing effect upon active sludge. Santrauka Mikroorganizmų augimo dinamika, t. y. priklausomybė tarp jų savitojo augimo spartos ir substrato koncentracijos, yra vienas iš svarbiausių veiksnių modeliuojant veikliojo dumblo kinetiką. Laboratorinėmis sąlygomis buvo atlikti eksperimentiniai nuotekų valymo tyrimai kompleksiškai įdėjus į substratą ir chloridų kaip papildomos užtaršos bei fermentinio preparato. Rezultatams palyginti buvo atlikti tyrimai ir be fermentinio preparato. Po įvairių technologinių procesų į valymo įrenginius patenka tokios mineralinės medžiagos kaip chloridai. Šios medžiagos biologiniu valymo būdu iš nuotekų nepašalinamos. Darbe nagrinėjama, kokios chloridų koncentracijos turi įtakos biologinio nuotekų valymo kokybei, veikliojo dumblo augimo dinamikai bei substrato biodegradacijai. Eksperimentų metu nustatytos tiriamų teršalų koncentracijos, turėjusios įtakos biologiniam valymo procesui: 400 mg Cl– /l ir didesnės sutrikdo mikroorganizmų veiklą, veiklusis dumblas biologiniam nuotekų valymui tampa netinkamas. Darbe modeliuojama veikliojo dumblo mikroorganizmų biocenozės dinamika, atliekant aerobinį nuotekų valymą. Nagrinėtas atvejis, kai nuotekų užtarša yra didesnė chloridų koncentracija. Veikliojo dumblo biocenozės dinamikai modeliuoti pasirinktas Monodo modelis. Atlikus eksperimentą nustatyti degradacijos koeficientai kd. Gautas Monodo diferencialinės lygties sprendinys, nusakantis veikliojo dumblo dinamiką. Skaitiniais metodais išspręsta veikliojo dumblo augimą bei substrato biodegradaciją nusakanti diferencialinių lygčių sistema. Įvertinus eksperimentų rezultatus nustatyti veikliojo dumblo sistemos degradacijos koeficientai įdėjus fermentinio preparato. Rezultatai parodė, kad fermentinis preparatas teigiamai veikia mikroorganizmų augimą t. y. veikliojo dumblo koncentracija mažėja lėčiau. Резюме Кинетика биомассы микроорганизмов, т. е. зависимость между концентрацией активного ила и концентрацией субстрата, один из важнейших аспектов в моделировании динамики активного ила. В лабораторных условиях были проведены экспериментальные исследования сточных вод в комплексе с добавлением в субстрат хлоридов как дополнительного загрязнения и ферментного препарата. Для сравнения результатов были проведены параллельные эксперименты без ферментного препарата. В результате технологических процессов в очистные сооружения попадают разные минеральные вещества, как, например, хлориды. Эти вещества методом биологической очистки не удаляются. В настоящей работе были исследованы концентрации хлоридов, влияющие на качество биологической очистки сточных вод, качество и кинетику активного ила и биодеградацию субстрата. Для определения влияния хлоридов на биологические процессы были проведены лабораторные исследования по определению биохимического потребления кислорода (БПК), концентрации активного ила и др. В результате эксперимента было установлено, что концентрация хлоридов, составляющая 400 мг/л и больше, поражает работу микроорганизмов, активный ил становится непригодным для биологической очистки cточных вод. Также исследовалось влияние ферментного препарата на качество очистки. Моделируя кинетику динамики активного ила, получено решение дифференциального уравнения, в котором идентифицированы коэффициенты деградации ила kd. В результате эксперимента определены коэффициенты деградации на систему активного ила в резервуаре с ферментным препаратом, т. е. концентрация активного ила уменьшается медленнее. Можно сделать вывод, что ферментный препарат эффективно влияет на концентрацию микроорганизмов.

Occurrence, Fate, and Impact of Triclosan and Other Antimicrobials to Wastewater Treatment Utilities

Occurrence, Fate, and Impact of Triclosan and Other Antimicrobials to Wastewater Treatment Utilities

The inhibitory effects of silver nanoparticles, silver ions, and silver chloride colloids on microbial growth

Emerging nanomaterials are of great concern to wastewater treatment utilities and the environment. The inhibitory effects of silver nanoparticles (Ag NPs) and other important Ag species on microbial growth were evaluated using extant respirometry and an automatic microtiter fluorescence assay. Using autotrophic nitrifying organisms from a well-controlled continuously operated bioreactor, Ag NPs (average size=14±6 nm), Ag + ions (AgNO 3), and AgCl colloids (average size=0.25 μm), all at 1 mg/L Ag, inhibited respiration by 86±3%, 42±7%, and 46±4%, respectively. Based on a prolonged microtiter assay, at about 0.5 mg/L Ag, the inhibitions on the growth of Escherichia coli PHL628-gfp by Ag NPs, Ag + ions, and AgCl colloids were 55±8%, 100%, and 66±6%, respectively. Cell membrane integrity was not compromised under the treatment of test Ag species by using a LIVE/DEAD Baclight™ bacterial viability assay. However, electron micrographs demonstrated that Ag NPs attached to the microbial cells, probably causing cell wall pitting. The results suggest that nitrifying bacteria are especially susceptible to inhibition by Ag NPs, and the accumulation of Ag NPs could have detrimental effects on the microorganisms in wastewater treatment.

Adsorbents made from waste ashes and post-consumer PET and their potential utilization in wastewater treatment

This study was carried out to prepare low-cost adsorbents from different types of waste ashes and post-consumer PET for use in industrial wastewater treatment. PET was melted and blended with ashes. The mixture was then carbonized to form different types of adsorbents. Heavy metal leaching from the adsorbents was greatly reduced compared to leaching from the bulk ashes. The BET surface area of the adsorbents ranged from 115 to 485 m 2/g. The acidic sites on the adsorbents varied from 0.84 to 1.56 meq./g, higher than that of the PET carbon. The adsorption of methylene blue (MB) or heavy metals on the adsorbents was not in accordance with their surface areas because acidic sites reaction, affinity adsorption and cation exchange all contribute to the adsorption of the adsorbents. The isotherm for MB adsorption on the adsorbents can be well described by the Langmuir or Freundlich equation but heavy metal adsorption cannot. It is believed that the adsorbents produced in this manner can be used in wastewater treatments for discoloration and heavy metal removal.

Feasibility of using a chlorination step to reduce excess sludge in activated sludge process

The ultimate disposal of excess sludge generated from activated sludge processes has been one of the most challenging problems for wastewater treatment utilities. Previous work has shown that excess sludge can be minimized successfully by using sludge ozonation to dissolve it into substrates to be oxidized in the aeration tank. However, this approach is a costly option. Therefore, as an alternative solution, we propose to use chlorination to replace ozonation in excess sludge minimization in the light of operational cost. To investigate the feasibility of this low cost approach, this paper mainly focuses on the effect of chlorination on sludge reduction rate, formation of trihalomethanes, sludge settleability, and effluent quality. Two identical activated sludge membrane bioreactors were continuously operated with synthetic wastewater under the same operation conditions for several months. During this period, one pilot unit was used as the reference system without chlorination of excess sludge, while another served as a testing unit, where excess sludge was taken out for conducting chlorination at a dose of 133 mg/g MLSS every day and the chlorinated liquor was then returned to the aeration tank. The sludge production rate and the water quality of both the units were analyzed daily. It was observed that the sludge production could readily be reduced by 65% once the chlorination treatment was involved. However, the chlorination treatment also resulted in poor sludge settleability as well as significant increase of soluble chemical oxygen demand in the effluent, which creates potential difficulties in the operation of a conventional treatment plant with gravity clarifiers. However, it has been demonstrated that by integrating the immersed membrane into the activated sludge process these difficulties can be overcome effectively.