Biological nutrient removal in municipal waste water treatment

INTRODUCTION MAIN PROBLEM IS THE RISING CONCENTRATION OF NUTRIENTS. NITROGEN AND PHOSPHORUS ARE THE PRIMARY CAUSES OF EUTROPHICATION. MOST RECOGNIZABLE MANIFESTATIONS ARE ALGAL BLOOMS. SYMPTOMS ARE LOW DISSOLVED OXYGEN, FISH KILLS, MURKY WATER AND DEPLETION OF FLORA AND FAUNA.

EUTROPHICATION BEGINNING IN TOBA LAKE, INDONESIA

BIOLOGICAL NUTRIENT REMOVAL(bnr) BIOLOGICAL NUTRIENTS ARE ORGANIC MATERIALS. BNR IS A PROCESS USED TO REMOVE NITROGEN AND PHOSPHORUS. USING MICRO-ORGANISMS.

BNR PROCESSES BNR IS COMPRISED OF TWO PROCESSES: BIOLOGICAL NITROGEN REMOVAL BIOLOGICAL PHOSPHORUS REMOVAL

EFFLUENT TN AND TP COMPONENTS AND ACHIEVABLE LIMITS Form Common Removal Mechanism Technology Limit, mg/L Total Nitrogen Ammonia-N Nitrification <0.5 Nitrate-N Denitrification 1-2 Particulate Organic-N Solids separation <1.0 Soluble Organic-N None 0.5-1.5 Total Phosphorus Soluble P Microbial uptake and/or Chemical precipitation 0.1 Particulate P Solids removal <0.05 EFFLUENT TN AND TP COMPONENTS AND ACHIEVABLE LIMITS  

BIOLOGICAL NITROGEN REMOVAL AMMONIA, NITRATE, PARTICULATE ORGANIC NITROGEN AND SOLUBLE ORGANIC NITROGEN. NITRIFICATION AND DENITRIFICATION. AMMONIA IS OXIDISED TO NITRITE AND NITRITE IS THEN OXIDISED TO NITRATE. REDUCTION OF NITRATE TO NITRIC OXIDE, NITROUS OXIDE AND NITROGEN GAS.

BIOLOGICAL PHOSPHORUS REMOVAL 8 BIOLOGICAL PHOSPHORUS REMOVAL SOLUBLE AND PARTICULATE PHOSPHORUS. THE TREATMENT PROCESS CAN BE DESIGNED TO PROMOTE THE GROWTH OF PAOs. PAOs CONVERT AVAILABLE ORGANIC MATTER TO PHAs.

Treatment processes INTEGRATED FIXED FILM ACTIVATED SLUDGE PROCESS SEQUENTIAL BATCH REACTOR PROCESS STEP FEED PROCESS MOVING BED BIOFILM REACTOR PROCESS MEMBRANE BIOLOGICAL REACTOR PROCESS OXIDATION DITCH PROCESS

INTEGRATED FIXED FILM ACTIVATED SLUDGE PROCESS(ifas) 1010 INTEGRATED FIXED FILM ACTIVATED SLUDGE PROCESS(ifas) COMBINES FIXED FILM TECHNOLOGY WITH CONVENTIONAL ACTIVATED SLUDGE. IMMERSE A SOLID SUPPORT MEDIA INTO AN AERATION BASIN. MEDIA CAN BE FIXED OR FLOATING. TEXTILE MESH MATERIAL, FLOATING SPONGES OR PLASTIC MEDIA. PROVIDES SURFACE AREA FOR BIOLOGICAL GROWTH TO ATTACH.

IFAS PROCESS(Cont…) CREATES ADDITIONAL BIOMASS. PROVIDES ADDITIONAL BIOLOGICAL ACTIVITY. INCREASES SOLIDS SETTLING. INCREASES WASTE WATER TREATMENT FACILITIES.

FLOATING MEDIA SYSTEMS FIXED MEDIA SYSTEMS FLOATING MEDIA SYSTEMS

Sequential batch reactor PROCESS(sbr) CONTINUOS FLOW SYSTEM. PRIMARLY FOR NITROGEN REMOVAL. FLEXIBLE, INEXPENSIVE AND EFFICIENT. OPERATIONAL COST IS HIGH. THREE PHASES FILL PHASE REACT PHASE SETTLE PHASE

REACT FILL SETTLE/DECANT SBR PROCESS SEQUENCE

STEP FEED PROCESS CONTINUOUS FLOW PROCESS. INFLUENT FLOW IS SPLIT TO SEVERAL FEED LOCATIONS. RECYCLE SLUDGE STREAM IS SENT TO THE BEGINNING. HIGHER SOLIDS RETENTION TIME IS ACHIEVED PROVIDING ENHANCED TREATMENT. PHOSPHORUS REMOVAL IS LIMITED.

STEP FEED PROCESS

Moving bed biofilm reactor PROCESS(mbbr) DIRECT DERIVATIVE OF FIXED FILM ACTIVATED SLUDGE PROCESS. HDPE CARRIER ELEMENTS ARE USED. PROVIDE SITES FOR BACTERIA ATTACHMENT. ALLOWS HIGHER CONCENTRATION OF ACTIVE BIOMASS. MORE TREATMENT CAPACITY. PHOSPHORUS REMOVAL REQUIRES ADDITIONAL STAGES.

JET AERATION SYSTEM PIPING WITHIN THE MBBR K1 CARRIER ELEMENT

Membrane Biological Reactor PROCESS(mbr) CONSISTS OF SEPARATE AERATION TANKS AND MEMBRANE FILTRATION TANKS. THE MEMBRANE ELEMENTS SEPARATE SOLIDS FROM THE TREATED EFFLUENT. EXCESS SOLIDS ARE WASTED DIRECTLY FROM THE AERATION TANKS. MEMBRANES VARY FROM HOLLOW TUBE FILTERS TO FLAT PANELS. REQUIRE SEVERAL CLEANING CYCLES.

KUBOTA MEMBRANE AND MEMBRANE BIOREACTOR

ZENON MEMBRANE AND MEMBRANE BIOREACTOR

OXIDATION DITCH PROCESS OXIDATION DITCH IS A LARGE CIRCULAR BASIN WITH AERATORS. REMOVES ORGANIC MATTER AND POLLUTANTS ADSORPTION, OXIDATION AND DECOMPOSITION. ENSURES STABLE, CONTINUOUS D.O MEASUREMENT. REDUCES OPERATING COSTS. ELIMINATES THE NEED FOR MANUAL CLEANING.

OXIDATION DITCH PROCESS

CASE STUDY: SOUTH MIDDLETON MUNICIPAL AUTHORITY EVALUATED THE TREATMENT PROCESSES. MOST FEASIBLE PROCESS IS THE IFAS PROCESS INCORPORATING MBBR TECHNOLOGY. INCREASED NITRIFICATION IMPROVED PROCESS STABILITY REDUCED CAPITAL AND CONSTRUCTION COST REDUCED ANNUAL ENRGY COST

APPROXIMATE TANK VOLUMES Reactor Process Train #1 Volume (gallons) Process Train #2 Anaerobic Zone 71,800 Pre-Anoxic Zone 65,000 Aerobic IFAS Zone 240,000 Post-Anoxic Zone 85,400 Re-Aeration Zone 24,700 APPROXIMATE TANK VOLUMES

BNR PROCESS MODELLING PRACTICAL IMPLEMENTATION OF BNR TECHNOLOGY. WIDELY AND SUCCESSFULLY USED. TO IMPROVE UNDERSTANDING OF THE BNR PROCESSES. TO OPTIMIZE DESIGN AND OPERATION OF THE BNR PROCESSES. A COMPUTER PROGRAMME SIMULATOR IS REQUIRED.

BNR PROCESS MODELLING(Cont..) TO IMPLEMENT ALL UNIT PROCESS MODELS AND LINK THEM. TO SET UP A WWTP WITH PARTICULAR FLOW SCHEME, INFLUENT CHARACTERISTICS AND OPERATION CONDITIONS. TO REPRESENT THE BIOLOGICAL TRANSFORMATIONS. THE MODEL NEEDS TO BE CALIBRATED AND VALIDATED BEFORE IT IS USED.

REQUIREMENTS TO SET UP A WWTP PROCESS MODEL

CONCLUSION BNR IS AN ESTABLISHED TECHNOLOGY. IMPLEMENTATION AND OPERATION IS A CHALLENGE. COMPLEX AND HIGH COST. REQUIRES TRAINED DESIGN ENGINEERS AND OPERATORS. BNR PROCESS MODELLING IS A USEFUL TOOL FOR DESIGN AND OPERATION OF WWTPs.

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