IN BIOPROCESS INDUSTRY Introduction to Waste Treatment ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2011/2012) Introduction to Waste Treatment

WASTE ? "Wastes" are substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law. Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, article 2 The goal of effective industrial waste treatment is directed towards the removal of all contaminants that adversely impact the water as well as air and land environments. (Nemerow and Agardy, 1998)

Industrial wastewater treatment Covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use. Most industries produce some wet waste although recent trends in the developed world have been to minimize such production or recycle such waste within the production process. However, many industries remain dependent on processes that produce wastewaters. Anthropogenic (from the Greek meaning manmade) effects, processes or materials are those that are derived from human activities, as opposed to those occurring in biophysical environments without human influence. The term is often used in the context of environmental externalities in the form of chemical or biological wastes that are produced as by-products of otherwise purposeful human activities.

Fundamentals of Wastewater Any water @ liquid that contains impurities or pollutants in the form of solids or gasses or their combinations in such a concentration that is harmful if disposed into the environment Impurities in ww are mainly due to the presence of solids in the water. The solids may be organic or inorganics in nature and may be present in suspended, colloidal, dissolved or in the various forms of their combinations. The prescribed limit or acceptable level of concentration of impurities or pollutants is laid down by the local authoroties such as Jabatan Alam Sekitar. The final discharge of ww will normally be either into the body of water or onto the land. The receiving bodies of water may be streams, lakes, ponds, canals, rivers, seas etc.

CONCEPT OF TREATMENT WASTEWATER TREATMENT The partial reduction @ complete removal of excessive impurities present in wastewater. The excessive impurities imply to the constituent (s) concentration(s) that is more than the acceptable level(s) for final or suitable reuse of treated wastewater. If the objective is to simply dispose of the final effluent into the body of water (receiving streams) or onto the land, the conc of specific constituents is reduced only up to acceptable limits prescribed by the local authorities Depends on the intended level of treatment

TYPES OF WASTEWATER Domestic Wastewater Industrial Wastewater WW Generated by large & medium scale industries. Used water which has been discharged from the residential. Vary in quantity & quality from industry to industry and process to process for the same industry Also known as municipal WW. Contains organics & inorganics solids & microorganism (bacteria) Contains organics & inorganics solids & microorganism (bacteria) The composition of WW depends on the source of its generation

STEP 1 : VOLUME REDUCTION Theories and Practices STEP 1 : VOLUME REDUCTION In general, the first step in minimizing the effects of industrial wastes on receiving streams may be accomplished by: In general, the first step in minimizing the effects of industrial wastes on receiving streams and treatment plants is to reduce the volume of such wastes. This may be accomplished by: Classifying wastes Conserving wastewater Changing production to decrease waster Reusing both industrial and municipal effluents as raw water supplies

Classification of Wastes If wastes are classified so that manufacturing-process waters are separated from cooling waters, the volume of water requiring intensive treatment may be reduced considerably. Waste from manufacturing processes: Example: Water discharged from dyeing and washing of textile fabrics. Water used as cooling agents in industrial processes: Example: Cooling waters (CW) have been found to be contaminated by small leaks, corrosion products or the effect of heat. However, CW for power plant may contain hazardous contaminants. Sometimes it is possible to classify and separate the process waters themselves so that only the most polluted ones are treated and the relatively uncontaminated ones are discharged without treatment.

Conservation of Wastewater Water conservation is waste saved. Example: Steel mills reuse CW to quench ingots Coal processes reuse water to remove dirt and other noncombustible materials from coal. Concentrated recycled wastewaters are often treated at the end of their period of usefulness, because usually it is impractical and uneconomical to treat the wastewaters as they complete each cycle. The savings are twofold: Water costs and waste-treatment costs are lower.

Changing Production to Decrease Wastes Changing production to decrease wastes is an effective method of controlling the volume of wastes but is difficult to put into practice. It is hard to persuade plant managers to change their operations just to eliminate wastes. Normally, the operational phase of engineering is planned by the chemical, mechanical, or industrial engineer whose primary objective is cost savings. The main considerations of the environmental engineer, on the other hand, include the protection of public health and the conservation

Reusing Both Industrial and Municipal Effluents for Raw Water Supplies Practiced mainly in areas where water is scarce or expensive, reusing industrial and municipal effluents for raw water supplies is proving a popular and economical method of conservation. Although there are many problems involved in reusing effluents for raw water supply, it must be remembered that any water supply poses problems to cities and industries. Because the problems of reusing sewage effluents are similar to those of reusing industrial effluents.

STEP 2: Contaminant Concentration Reduction Waste strength reduction is the second major objective for an industrial plant concerned with waste treatment. Any effort to find means of reducing the total pounds of polluting matter in industrial wastes will be well rewarded by the savings earned by reduced requirements for waste treatment. The strength of wastes may be reduced by: (1) process changes (2) equipment modifications (3) segregation of wastes (4) equalization of wastes (5) by-product recovery (6) proportioning wastes (7) monitoring waste streams All will be cover on the last chapter (Waste Minimization Strategy)