Wastewater-Treatment-for-the-Sugar-Industry.pptx

Wastewater-Treatment-for-the-Sugar-Industry

1. Wastewater Treatment for the Sugar Industry A detailed overview of the sources, characteristics, and primary treatment technologies used for managing wastewater generated by sugar production. Presented by Hülya Pala, EGE University, Chemical Engineering

2. Global Sugar Production: Cane vs. Beet Globally, sugar is primarily extracted from two sources: sugar cane and sugar beet. The industry is a crucial supplier for beverages, confectionery, and baking products, with production reaching around 460 million tonnes annually. Cane Sugar (80% of Production) Derived from sugar cane, a tropical tall true grass. Grows exclusively in tropical and subtropical zones. Mature stalk composition: 11-16% fiber, 12-16% soluble sugars, 63-73% water. Top producers include Brazil (72%), India, China, Thailand, Pakistan, and Mexico. Beet Sugar (20% of Production) Derived from sugar beet, a conical, white, fleshy tap root. Grows entirely in the temperature zone. Root composition: 75% water, 20% sugar, and 5% fiber. Top producers include France, the United States, Germany, Russia, and Turkey.

3. The Environmental Challenge of Sugar Wastewater Untreated wastewater from the sugar industry poses significant pollution problems in both aquatic and terrestrial ecosystems, often resulting in unpleasant odors. Primary Sources of Wastewater Cleaning operations (milling house floor, boiling house divisions like evaporators, clarifiers, vacuum pans, centrifugation). Periodical cleaning of heat exchangers and evaporators with NaOH and HCl to remove scales. Leakages from pumps, pipelines, and centrifuging house. Contaminated boiler blowdown, spray pond overflow, and condenser cooling water. Key Characteristics Brown color, low pH, and high temperature. High BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand). Contains carbohydrates, nutrients, oil and grease, chlorides, sulfates, and heavy metals. High percentage of dissolved organic and inorganic matter.

4. Typical Wastewater Composition and Discharge Standards Sugar industry wastewater is highly concentrated in pollutants, necessitating treatment to meet regulatory standards for discharge into inland surface water or land for irrigation. 1. pH 5.5–9.0 5.5–9.0 2. BOD (mg/L) 30 100 3. TSS (mg/L) 100 200 4. Oil & Grease (mg/L) 10 10 Note: Typical average BOD is 1998 mg/L, far exceeding the 30 mg/L standard for inland discharge, highlighting the need for robust biological treatment.

5. Integrated Treatment Strategy Effective treatment of sugar industry wastewater requires a combination of mechanical, chemical, and biological measures to reduce suspended solids and soluble organic matter. 01 Pre-Treatment & Mechanical Screening, grit removal, flow equalization, sedimentation, or dissolved air flotation are used to reduce the suspended solids (SS) load. 02 Biological Treatment Applied for the reduction of soluble organic matter and disinfection. This includes both aerobic and anaerobic processes, which are highly suitable due to the easily biodegradable nature of sugars and volatile fatty acids. 03 Physicochemical Methods Used in addition to biological methods, including coagulation, flocculation, and electrochemical processes, often for primary purification and removal of colloidal/dissolved solids.

6. Aerobic Biological Treatment Methods Aerobic treatment involves the degradation of organic matter in the presence of oxygen. Conventional methods are effective but often require significant space or have high operational costs. Conventional Aerobic Systems Activated Sludge Process Trickling Filters (Figure 1) Aerated Lagoons (Figure 2) Combination systems Challenges with Lagoons While economic, traditional lagoons require large areas and emit unpleasant odors. Aerated lagoons reduce residence time but still require large areas and have high oxygen consumption.

7. Anaerobic Treatment: Advantages and Limitations Anaerobic treatment is widely favored for concentrated wastewater, such as that from the sugar industry, due to its efficiency and resource recovery potential. Key Advantages Lesser energy required for operation. Methane production from organic degradation, serving as an energy source. Lesser sludge production, significantly reducing disposal costs. Anaerobic Reactors Used Anaerobic Batch Reactor Anaerobic Fixed-bed Reactors (AFR) Up-flow Anaerobic Fixed Bed (UAFB) reactor Up-flow Anaerobic Sludge Blanket (UASB) reactor Primary Limitation Oil and grease are not easily degraded by anaerobic processes. They produce long-chain fatty acids during hydrolysis, which can inhibit methanogenic bacteria and retard methane production.

8. Focus on UASB: Up-flow Anaerobic Sludge Blanket The Up-flow Anaerobic Sludge Blanket (UASB) reactor is a highly applicable technology for treating various types of high-strength wastewater, including that from the sugar industry, distillery, and dairy sectors. The Four Stages of Anaerobic Digestion 1 Hydrolysis Complex organic molecules are broken down into soluble compounds. 2 Acidogenesis Small organic molecules are converted into fatty acids. 3 Acetogenesis Fatty acids are converted to acetic acid and CO2. 4 Methanogenesis Final conversion to methane (CH4), the valuable energy source.

9. Advanced Physicochemical Treatment Beyond biological methods, physicochemical processes are employed for primary purification and removal of non-biodegradable or difficult-to-treat components. Coagulation/Flocculation Inorganic coagulants are used to collect insoluble particles and dissolved organic materials into larger flocs, which are then removed by sedimentation or filtration. Widely used for suspended, colloidal, and dissolved solids removal. Electrochemical Treatment An emerging technology involving three main processes: Electro-Oxidation, Electro-Coagulation, and Electro-Flotation.

10. Electrochemical Processes in Detail Electrochemical methods leverage electrical currents to drive chemical reactions, offering efficient ways to remove organics and suspended matter from sugar industry wastewater. Electro-Oxidation (EO) Organic materials are oxidized to carbon dioxide, water, or other oxides using electrochemically generated reactive oxygen or oxidizing agents. Electro-Coagulation Involves the generation of anode material hydroxides and poly hydroxides, which remove organics through coagulation. Electro-Flotation Pollutants are removed with the help of buoyant gas bubbles generated during electrolysis, which carry the pollutant materials to the liquid surface for skimming. These advanced methods provide robust solutions for achieving stringent effluent standards.