WASTEWATER TREATMENT Lili sugiyarto [email protected] The primary goal  The removal and degradation of organic matter under controlled condition Three major steps  Primary treatment  Secondary treatment  Tertiary treatment Primary treatment A physical process that involves the separation of large debries, followed by sedimentation  Comprises grit tank and settling tank  Settling tank also known as sedimentation tank (sand and gravel)/clarifier  About half suspended organic solids settle to the bottom as sludge or biosolids (primary sludge) Secondary treatment  Consist of biological degradation (decomposed and the number of pathogens is reduced)  The effluent from primary treatment may be pumped into a tricklingfilter bed ( an aeration tank/a sewage lagoon  Disinfection step is generally included at the end of treatment Large-scale wastewater treatment Trickling filter bed • • • Rocks provide a matrix supporting the growth of a microbial biofilm that actively degrades the organic material under aerobic conditions Effluen from primary treatment is pumped into a tank and mixed with bacteria-rich known as activated sludge air and pure oxygen pumped through the mixture promotes bacterial growth and decomposition of the organic material Then goes to a secondary settling tank  Water siphon off the top of the tank  Sludge is removed from the bottom  Some of the sludge is used as an inoculum for the incoming activated sludge  The sludge that is not return as secondary sludge Trickling filters  Gram negative bacteria : Zooglea, Pseudomonas, Alcaligenes, Achromobacter, Flavobacterium  Gram positive : Corynebacterium, etc  Fungi : Fusarium, Trisporon, Ascoidea In secondary treatment  It contains a high level of the organic nutrients phosphate and nitrate  Nitrosomonas : oxidize ammonia to nitrite  Nitrobacter : oxidize nitrite to nitrate Secondary treatment  Aerobic digestion tank  Anaerobic digestion tank Anaerobic digestion tank  The degradatif and fermentative process divided into 2 stages : acid forming and methane forming  Genera of Methane forming stage : Methanobacterium, Methanosarcina, Methanococcus (convert acetate, hydrogen and CO2 to methane) The major metabolic stages       Complex organic compounds (polysaccharides, fats, protein) Hydrolisis Hydrolysis by extracellular bacterial enzymes Monomeric compounds (sugar, fatty acids, amino acids) Higher organic acids Acidogenesis Acetic acid, H2, CO2 Acetogenesis CH4 methanogenesis Types of Bioremediation  In situ bioremediation  Composting  Landfarming  Above-ground bioreactors Activated sludge process Activated sludge flocs Note filamentous bacteria Note Vorticella and other protozoa Activated sludge model L L0 L L L L Composition of sludge © PK, 2006 page 21 Urban Water Systems • Predominantly water • Micro-organisms • Viruses, pathogens, germs in general • Organic particles, heavily bio-degradable • Organic compounds, inert, adsorpted to sludge flocs • Heavy metals • Micro-pollutants, pharmaceuticals, endocrine disrupters  All non-degraded compounds extracted from wastewater are found in the 12 Sludge treatment sludge Activated sludge plants Hyperion, Playa del Rey, CA) Primary aeration tank Tertiary treatment  Involve some type of physicochemical treatment such as coagulation, filtration, activated carbon adsorbtion of organics and additional disinfectan Goals of sludge treatment © PK, 2006 page 25 Urban Water Systems Volume reduction • Thickening • Dewatering Elimination of pathogenic germs • If used in agriculture as fertiliser or compost Stabilisation of organic substances • • • • Recycling of substances • Nutrients, fertiliser • Humus • Biogas Gas production Reduction of dry content Improvement of dewatering Reduction of odour 12 Sludge treatment Overview © PK, 2006 page 26 Urban Water Systems Wastewater treatment Process water Primary, secondary, tertiary sludge Thickening Energy Hygienisation Stabilisation Biogas Thickening Agriculture Dewatering Disposal site Drying Construction industry 12 Sludge treatment Gujer (1999) Incineration Atmosphere Oxygenated systems Cryogenic air separation facility, Hyperion, Playa del Rey, CA) Typical steps in modern wastewater treatment Flotation unit © PK, 2006 page 29 Urban Water Systems 12 Sludge treatment Examples of naturally transmissible catabolic plasmids Primary substrate Plasmid Size (kb) Host Toluene pWW0 (TOL) 117 Pseudomonas putida mt-2 Alkylbenzene ASL sulfonate 91.5 Pseudomonas testosroni octane ~500 P.oleovorans 83 P. Putida PpG7 OCT Naphthalene Nah7 Pseudomonas putida mt-2  Chromosomal gene encode ortho pathway : acetyl CoA and succinate  TOL plasmid encodes meta pathway : acetaldehide and pyruvic acid TOL (pWW0) plasmid  The genes encoding catabolic enzymes : xyl genes  The Xyl genes : xyl ABC (upper) and xyl XYZLEGFJKIH (lower/meta) Xyl ABC  Encode degradation toluene and xylene to benzoate and metylbenzoates Xyl XYZLEGFJKIH  Encodes degradation of benzoate and methylbenzoate to acetaldehyde and pyruvat