Anaerobicaerobic treatment of industrial and municipal wastewater

AbstractAnaerobicaerobic systems have been remarkably employed in industrial and municipal wastewater treatment for many years. While previously most treatment of wastewaters have been carried out in conventional anaerobicaerobic treatment plants, in recent years, high rate anaerobicaerobic bioreactors have been increasingly employed for wastewaters with high chemical oxygen demand (COD). This paper provides a review of the various types of high rate anaerobicaerobic water treatment techniques currently available including high rate bioreactors and integrated anaerobicaerobic bioreactors. The integrated bioreactors are classified into four types, which are integrated bioreactors with physical separation of anaerobicaerobic zone, integrated bioreactors without physical separation of anaerobicaerobic zone, anaerobicaerobic Sequencing Batch Reactors (SBR), and combined anaerobicaerobic culture system. The integration of aerobic and anaerobic degradation pathways in a single bioreactor is capable of enhancing the overall degradation efficiency. The merits of different integrated anaerobicaerobic bioreactors are highlighted and comparison made to identify possible future areas of research to fully utilize these methods of wastewater treatment. The comparison demonstrates that using an integrated bioreactor with stacked configuration in treating high strength industrial wastewaters is advantageous due to minimal space requirements, low capital cost and excellent COD removal efficiencies. 1. IntroductionOver the last century, continued population growth and industrialization have resulted in the degradation of various ecosystems on which human life relies on. In the case of ocean and river quality, such pollution is primarily caused by the discharge of inadequately treated industrial and municipal wastewater. On initial discharge, these wastewaters can contain high levels of inorganic pollutants which can be easily biodegradable, but whose impact load on the ecosystems, either in Total Suspended Solids (TSS), Bio-chemical Oxygen Demand (BOD5 ), or Chemical Oxygen Demand (COD), may be in the tens of thousands mg/L [1]. To combat this increasing burden on our aquatic environment, increasingly strict regulation on pollution discharge is being implemented by various governmental bodies, with focus primarily on waste reduction. The treatment systems developed by industry are frequently regarded as a regulatory obligation, increasing capital and running costs and yielding negative economic returns. Compliance to environ-mental legislations should not necessary l In the treatment of wastewater, biological treatment appears to be a promising technology to attain revenue from Certified Emission Reduction (CER) credits, more commonly known as carbon credits from the CDM as methane gas is generated from anaerobic digestion and can be utilized as renewable energy. With appropriate analysis and environmental control, almost all wastewaters containing biodegradable constituents with a BOD/COD ratio of 0.5 or greater can be treated easily by biological means [2]. In comparison to other methods of wastewater treatment, it also has the advantages of lower treatment costs with no secondary pollution [3]. Both aerobic and anaerobic processes can be used; the former involves the use of free or dissolved oxygen by microorganisms (aerobes) in the conversion of organic wastes to biomass and CO2 while in the latter complex organic wastes are degraded into methane, CO2 and H2 O through three basic steps in the absence of oxygen. Aerobic biological processes are commonly used in the treatment of organic wastewaters for achieving high degree of treatment efficiency, while in anaerobic treatment, considerable progress has been achieved in anaerobic biotechnology for waste treatment based on the concept of resource recovery and utilization while still achieving the objective of pollution control [4,5].ead to the creation of additional costs, but can instead provide a secondary source of income. In general, aerobic systems are suitable for the treatment low strength wastewaters (biodegradable COD concentrations s than 1000 mg/L) while anaerobic systems are suitable for the atment of high strength wastewaters (biodegradable COD concentrations over 4000 mg/L). Highly polluting industrial wastewaters are preferably treated an anaerobic reactor due to the high level of COD, potential energy generation and low surplus sludge production. How-er in practical applications, anaerobic treatment suffers from the w growth rate of the microorganisms, a low settling rate, pross instabilities and the need for post treatment of the noxious aerobic effluent which often contains ammonium ion (NH4 + ) d hydrogen sulfide (HS ) [8]. In most applications, despite the ciency of the anaerobic process is high, complete stabilization the organic matter is impossible anaerobically due to the high ganic strength of the wastewater. The final effluent produced the anaerobic treatment contains solubilized organic matter. is is suitable for aerobic treatment, indicating the potential of ng anaerobicaerobic systems [9] and subsequent post treatment using aerobic treatment is required to meet the effluent charge standard. New technologies have been developed over the years to overcome the disadvantages of conventional anaerobicaerobic systems. Anaerobicaerobic system using high rate bioreactors (such as upflow anaerobic sludge blanket (UASB), filter bioreactor, fluidized bed reactor, membrane bioreactor) are adopted in order to provide a treatment process which is both technologically and economically viable with the dual goals of resource recovery and compliance with current legislation for effluent discharge. A more intensive form of biodegradation can also be achieved by integrating anaerobic and aerobic zones within a single bioreactor. Essentially, there are four types of integrated anaerobicaerobic bioreactor. These are integrated bioreactors with physical separation of anaerobicaerobic zone, integrated bioreactor s without physical separation of anaerobicaerobic zone, Sequencing Batch Reactors (SBR) based on temporal separation of the anaerobic and the aerobic phase, and (iv) combined anaerobicaerobic culture system based on the principle of limited oxygen diffusion in microbial biofilms. An overview of the most frequently applied bioreactors is delineated in Tables 24, with specific attention on the evaluation of their treatment efficiency in terms of organic removal.1. Anaerobicaerobic systems using high rate bioreactorsThe right combination and sequence of treatment methods is the key to the successful handling of industrial and municipal wastewater. The combinations of different anaerobic and aerobic bioreactors have been applied to treat a broad range of industrial wastewater including textile industry wastewater, food solid waste leachate, pulp and paper industry wastewater, pharmaceutical industry wastewater, mixture of olive oil mill wastewater and primary municipal wastewater, starch industry wastewater, green olive debittering wastewater, slaughter house wastewater, and palm oil mill effluent (POME). The anaerobicaerobic systems using high rate bioreactors reviewed in this paper achieve high COD removal (in excess of 70%) at short HRT (ranging from few hours to few days). Therefore, the anaerobicaerobic treatment is an efficient method to treat industrial and municipal wastewater.2. Integrated anaerobicaerobic bioreactors

In recent years, substantial attention has been paid towards the compact high-rate bioreactors for wastewater treatment to meet the strict constraints with respect to space, odor, view, and biosolids production. Thus, the integrated bioreactors which combine the aerobic and anaerobic processes in a single reactor are seen as a viable alternative.

A combination of aerobic and anaerobic degradation path-ways in a single reactor is capable of enhancing the overall degradation efficiency [66]. The integrated bioreactors are cost effective, efficient and have smaller foot prints as compared to the aforementioned anaerobicaerobic systems. Nonetheless, the design, operation and process development of integrated anaerobicaerobic bioreactors are still in its infancy and limited to a few studies.

3. ConclusionAnaerobicaerobic treatments receive great attention over the past decades due to their numerous advantages such as low energy consumption, low chemical consumption, low sludge production, vast potential of resource recovery, less equipment required and high operational simplicity. However, conventional anaerobicaerobic systems are found to have operational limitations in terms of long HRT, space requirement and facilities to capture biogas. The applications of newly developed high rate bioreactors address these limitations and provide increased organic matter removal at shorter HRT and higher methane yields for biogas production.

In order to meet strict constraints with respect to space, odors and minimal sludge production, considerable attention has been directed towards the integrated anaerobicaerobic bioreactors which combine the aerobic and anaerobic process in a single bioreactor. With simple yet cost effective technology, the generation of renewable energy and outstanding treatment efficiency, it is envisaged that the compact integrated bioreactors will be able to treat a wide range of high organic strength industrial and municipal wastewater. However, most of the integrated bioreactors reported in this work lack large scale implementation within industry and further work is required to evaluate the performance of these promising reactors on a larger scale. Besides, further improvements such as installation of biogas capture system and utilization of sus-pended carrier or packing medium are considered essential.

Tratament anaerob aerob a apelor uzate industriale i municipale

AbstractSisteme anaerobe aerobic au fost utilizate remarcabil n tratarea apelor uzate industriale i municipale de mai muli ani. n timp ce majoritatea anterior tratamentul apelor uzate au fost efectuate n instalaiile convenionale de epurare-anaerobe aerobic, n ultimii ani, rata nalt anaerobe aerobic Biore-actori au fost folosite din ce n ce ape uzate cu cerere mare de oxigen chimic (COD). Aceasta lucrare ofera o revizuire a diferitelor tipuri de rata mare anaerobe aerobic de tratare a apei tehnologie-tehnicilor disponibile n prezent, inclusiv bioreactoare mare rata i bioreactoare integrate anaerobe aerobic. Bioreactoare integrate sunt clasificate n patru tipuri, care sunt bioreactoare integrate cu fiz-iCal separare a zonei anaerob aerobic, bioreactoare integrate fr separarea fizic a-anaerob aerobic zone, (iii)-anaerobe aerobic reactori secventiere lot (SBR), i (iv) sistem combinat de cultur-anaerob aerobic. Integrarea ci de degradare aerobe i anaerobe ntr-un singur bioreactor este capabil de a spori eficiena global degradare. Meritele diferitelor-anaerobe aerobic bioreactoare ras-inte sunt evideniate i compararea fcut pentru a identifica posibile domenii viitoare de cercetare s utilizeze pe deplin aceste metode de tratare a apelor uzate. Comparaia demonstreaz c, utiliznd un bioreactor integrat cu configurare stivuite n tratarea nalt rezisten industriale wastew-Aters este avantajoas datorit cerinelor de spaiu minime, costuri de capital reduse i eficien de ndeprtare excelente COD (peste 83%).1. Introduceren ultimul secol, creterea populaiei a continuat i Indus-trialization au dus la degradarea diferitelor ecosisteme n care viaa uman se bazeaz pe. n cazul ocean i de calitate ru, astfel poluarea este cauzat n primul rnd de deversarea INAD-equately tratate a apelor uzate industriale i municipale.Pe de descrcare de gestiune iniial, aceste ape uzate pot conine niveluri ridicate de poluanti anorganici care pot fi uor biodegradabil, dar al cror impact sarcin asupra ecosistemelor, fie n total solide n suspensie (TSS), Bio-chimic de oxigen (CBO5), sau consumul chimic de oxigen ( COD), poate fi n zeci de mii mg / l [1]. Pentru a combate aceast povar tot mai mare asupra mediului acvatic, reglementarea n ce mai stricte privind descrcarea de poluare este implementat de diferite organisme guvernamentale, cu accent n primul rnd pe reducerea deeurilor. Sistemele de tratare dezvoltate de industrie sunt adesea considerate ca fiind o obligaie de reglementare, creterea de capital i costurile de funcionare i rezultnd profituri economice negative. Respectarea legislaiilor-Environ mental ar trebui s nu am nevoie n tratarea apelor reziduale, epurare biologic pare a fi o tehnologie promitoare pentru a atinge venituri de la Certified Emis-sion reducere (CER) de credite, mai cunoscut sub numele de credite de carbon din CDM ar fi gaz metan este generat prin digestia anaerob i pot fi utilizate ca energie regenerabil. Cu analiza dup caz i de control al mediului, aproape toate apele reziduale care conin componeni biodegradabili cu un raport BOD / COD de 0,5 sau mai mare pot fi tratate cu uurin prin intermediul biologice [2]. n comparaie cu alte metode de tratare a apelor uzate, aceasta are, de asemenea avantaje de costuri de tratament mai mici fr pol-Rezo- secundar [3]. Ambele procese aerobe i anaerobe pot fi folosite; fostul implic utilizarea de oxigen liber sau dizolvat de microor-ganisms (aerobe), n conversia deeurilor organice pentru biomas i CO2 n timp ce n urm deeurilor organice complexe sunt degradate n metan, CO2 i H2O prin trei etape de baz (hidroliz, acidogenez inclusiv acetogenezei i metanogeneza), n absena oxigenului.Aerobic procese biologice sunt de obicei utilizate n tratamentul apelor uzate organice pentru realizarea grad ridicat de eficien tratament, n timp ce n tratamentul anaerob, progrese considerabile au fost realizate n domeniul biotehnologiei anaerobe pentru tratarea deeurilor bazat pe conceptul de recuperare a resurselor i de utilizare n timp ce nc atingerea obiectivului de control al polurii [4,5] .ead la crearea de costuri suplimentare, dar poate oferi n schimb o surs secundar de venit. n general, sistemele de aerobic sunt potrivite pentru tratament a apelor uzate rezisten sczute (biodegradabile COD concentraii s dect 1000 mg / l) n timp ce sistemele anaerobe sunt potrivite pentru atment a apelor reziduale de nalt rezisten (COD biodegradabil con-ntrations peste 4000 mg / l). foarte poluante apele uzate industriale sunt, de preferin, un reactor anaerob tratate din cauza nivelului ridicat de COD, potenialul de generare de energie i producia sczut de nmol excedent. Cum-er in aplicatii practice, tratament anaerob sufer de rata de cretere n greutate a microorganismelor, o rat sczut de decantare, instabilitile pro-SS i nevoia de tratament post a efluentului aerobic nocive care conine adesea ion amoniu (NH4 +) d hidrogen sulfur (HS-) [8]. In majoritatea aplicaiilor, n ciuda efici- al procesului anaerob este stabilizare ridicat, complet materia organic este imposibil anaerob datoreaz rezistenei Ganic ridicat al apei uzate. Efluentul final realizat tratamentul anaerob conine materie organic solubilizat. este este potrivit pentru tratamentul aerob, indicnd potenialul sistemelor anaerobe aerobic ng [9] i este necesar dup tratament ulterior-nt folosind tratament aerob pentru a satisface standardele de ncrcare a efluenilor. Noile tehnologii au fost dezvoltate de-a lungul anilor pentru a depi dezavantajele sistemelor anaerobe aerobic convenionale. Sistemul utilizeaz bioreactoare mare rata (cum ar fi flux ascendent ptur nmol anaerob (UASB), filtru bioreac-tor, reactor cu pat fluidizat, membrana bioreactor)-anaerob aerobicsunt adoptate pentru a asigura un proces de tratare care este att tehnologic i economic viabil cu obiectivele duble de recuperare a resurselor i respectarea legislaiei n vigoare pentru evacuarea apelor reziduale. O form mai intens de biodegradare se poate realiza prin integrarea anaerobe si zone de aerobic ntr-o singur bioreac-tor. n esen, exist patru tipuri de bioreactor integrat-anaerob aerob. Acestea sunt (i) integrat bioreactoare cu separarea fizic a zonei anaerob aerobic, (ii) bioreactor integrate s, fr separare fizic a zonei anaerob aerobic, (iii) Reactori secventiere Batch (SBR), pe baza temporal separa-TION a anaerob i faza aerob, i (iv) sistemul de cultur anaerob aerob combinat bazat pe principiul difuziei oxigenului limitate n biofilme microbiene. O privire de ansamblu asupra bioreactoare cele mai fre-quently aplicate este delimitat n tabelele 2-4, cu o atenie deosebit pe evaluarea eficienei tratamentului n ceea ce privete eliminarea organice. 2. Sisteme anaerobe aerobic utiliznd bioreactoare rata mare combinaia potrivit i secvena metode de tratament este cheia pentru manipularea cu succes a industriale i municipale wastewa-ter. Combinaiile de diferite anaerobe i aerobe bioreactoare au fost aplicate pentru a trata o gama larga de ape uzate industriale, inclusiv industria apelor uzate textile, produse alimentare levigatului deeuri solide, industria celulozei i hrtiei apelor uzate, industria apelor uzate farmaceutice, amestec de msline apelor uzate fabrica de ulei i ap uzat municipal primar, amidon industrie a apelor uzate, msline verde deb-ittering apelor uzate, abator apelor uzate, precum i de palmier presa de ulei apelor reziduale (POME). Tabelul 2 prezint sistemele de anaerobe aerobic utiliznd bioreactoare mari rata de cazul n care tratamentul se efectueaz n dou bioreactoare separate, conectate n serie. Sistemele-anaerobe aerobe utiliznd bioreactoare rat mare analizate n aceast lucrare obine o ndeprtare COD ridicat (peste 70%) la HRT scurt (de la cteva ore pn la cteva zile).Prin urmare, tratamentul anaerob-aerob este o metod eficient de a trata apele uzate industriale i municipale. 3. Bioreactoare integrate anaerobe aerobic n ultimii ani, o atenie important a fost acordat ctre compacte bioreactoare rata mare de epurare a apelor uzate pentru a satisface constrngerile stricte cu privire la spaiu, miros, vedere, i producia biosolids. Astfel, bioreactoare integrate care combin procesele aerobe i anaerobe ntr-un singur reactor sunt privite ca o alternativ viabil. O combinaie de degradare aerobe i anaerobe de cale-moduri ntr-un singur reactor este capabil de a spori eficiena degradrii global [66]. Bioreactoare integrate sunt rentabile, eficient i au printuri picior mai mici n comparaie cu sistemele de anaerobe aerobic menionate mai sus. Cu toate acestea, proiectarea, funcionarea i dezvoltarea procesului de bioreactoare integrate-anaerobe aerobe sunt nc n faz incipient i limitat la cteva studii. 4. Concluzie tratamente anaerob-aerob primi o atenie deosebit n ultimele decenii ca urmare a numeroaselor lor avantaje, cum ar fi consumul redus de energie, consum redus chimic, producia de nmol redus, potenial mare de recuperare a resurselor, echipamente mai puin solicitate i simplitate operaional ridicat. Cu toate acestea, sistemele anaerobe aerobic convenionale gasite de a avea limit ii-operaionale n ceea ce privete HRT lung, cerina de spaiu i faciliti pentru a captura de biogaz. Cererile de rata mare Biore-actori nou dezvoltate aborda aceste limitri i s ofere ndeprtarea materiei organice a crescut la HRT scurt i randamente mai mari de metan pentru producerea de biogaz. Pentru a rspunde constrngerilor stricte cu privire la spatiu, mirosuri i de producie minim de nmol, o atenie deosebit a fost ndreptat spre bioreactoare integrate anaerobe aerobic care combin procesul aerobe i anaerobe ntr-un singur Biore-actor.Cu simpla costa nc tehnologie eficient, generarea de energie din surse regenerabile i a eficienei tratamentului remarcabil, este ca bioreactoare integrate compacte vor putea trata o gama larga de rezisten organic ridicat a apelor uzate industriale i municipale de vrst ENVIS. Cu toate acestea, cele mai multe dintre bioreactoare integrate raportate n aceast lucrare lipsa de punere n aplicare pe scar larg n industrie i n munc este necesar pentru a evalua performana acestor reactoare promitatoare pe o scar mai larg. n plus, mbuntirea n continuare, cum ar fi instalarea unui sistem de captare a biogazului i utilizarea purttor melor-sus sau mediu de ambalare sunt considerate eseniale.