ERT 417 4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM

ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011) ‘Physical Treatment Processes of Industrial Waste’ (Part A) By; Mrs Hafiza Binti Shukor

At the end of these topic, students should be able to acquire these ability: v. INTERPRET, COMPARE, JUSTIFY and CHOOSE the physical treatment methods for waste treatment in industries. v. CALCULATE and DESIGN the basic structure of waste treatment unit operations By; Mrs Hafiza Binti Shukor

INTRODUCTION OF WASTEWATER TREATMENT PLANT DESIGN Wastewater Bar Rack Grit Chamber PRETREATMENT PROCESS Equalization Basin Primary Settling PRIMARY PROCESS Biological Treatment Secondary Settling Advance Wastewater Treatment SECONDARY PROCESS TERTIARY PROCESS ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

PRETREATMENT PROCESS ( Several devices/structures are placed UPSTREAM to the PRIMARY TREATMENT) Objectives: v. Protection to the WWTP equipment v. Seldom used in industrial WWTP Pretreatment Devices/structures: 1) BAR RACKS • remove large object that would damage @ foul pumps, valves and other mechanical equipment • Eg. Rags, logs, paper, plastics, rocks and leaves. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

Fig. 1 : Bar Screen / Bar Rack v. Consists of a series of parallel bars or a perforated screen placed in a channel. v. The flow passes through the screen and the large solids are trapped on the bars for removal. v. The bar screen may be coarse (2 -4 inch openings) or fine (0. 75 -2. 0 inch openings). v. The bar screen may be manually cleaned or mechanically cleaned (performed frequently enough to prevent solids buildup and reduce flow into the plant) ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

2) GRIT CHAMBER • Remove grit-inert, dense materials that tends to settle in corners, bends, reducing flow capacity and ultimately clogging pipes and channels • Eg. Sand, broken glass, silt, etc v. To remove the heavy inorganic solids, which could cause excessive mechanical wear. v. Grit includes sand, gravel, clay, egg shells, coffee grounds, metal filings, seeds and other similar materials. v. There are several devices or processes used for grit removal. All of the processes are based on the fact that grit is heavier than the organic solids that should be kept in suspension for subsequent treatment. v. Grit removal processes use gravity/velocity, aeration or centrifugal force to separate the solids from the wastewater. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

Pretreatment Devices/structures (continue……): 3) COMMINUTION • Devices that can CHOP UP wastewater solids by revolving cutting bars • It placed downstream of the GRIT CHAMBER to protect the cutting bars from abrasion • Cutting from the communitor are returned directly to the wastewater v. Its reduce solids to a size that can enter the plant without causing mechanical problems or clogging. v. In this device all of the wastewater flow passes through the grinder assembly. v. The grinder consists of a screen or slotted basket, a rotating or oscillating cutter and a stationary cutter. v. Solids pass through the screen and are chopped or shredded between the two cutters. v. The comminutor will not remove solids that are too large to fit through the slots, and it will not remove floating objects. The materials must be removed manually ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

Pretreatment Devices/structures (continue……): 4) FLOW EQUALIZATION • To minimize fluctuations in WW characteristics in order to provide optimum conditions for subsequence process • To provide adequate dampening of organic fluctuations in order to prevent shock loading to biological system • Provide adequate p. H control • Provide cont. feed to biological system • Provide capacity for controlled discharge • To prevent high conc. of toxic materials from entering the biological treatment plants. Q Q t Bar Screen / communitor Grit Removal Equalization Basin t Primary Treatment Effluent for further treatment ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

Flow diagram of a typical preliminary treatment / pretreatment system Sump & Pump House Bar Screen (screenings) Grit Chamber (grits) Skimming Tank (oil & grease) Effluent for discharge or further treatment ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

PRIMARY PROCESS ( primary & secondary process handle MOST of the NON-TOXIC wastewater) Objectives: v. Prepare WW for biological treatment (stabilize organic) v. Remove + 60% SS and 35% BOD 5 in sewage Devices/structures: • Sedimentation , accelerated gravity separation, floatation, filtration, gas stripping, chemical precipitation, adsorption etc. • Remove by settling @ floating • Oil, gas and suspended solid are removed by floatation, sedimentation and filtration. • Also neutralization process and equalization process (no fluctuation/ variation in flow and concentration of WW) ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

SECONDRY PROCESS Objectives: v. Speed up natural process of breaking down biodegradable organics v. Remove up to 85 % SS and BOD 5 Devices/structures: • Activated sludge, extended aeration, rotating biological contacting (RBC), trickling filter, aerated lagoons, sequencing batch reactor etc • Biological degradation of soluble organics. • Mostly aerobically in an open aerated vessels @ lagoon • Speed up natural processes of breaking down biodegradable organics • Cannot remove N, P, heavy metals, pathogens, bacteria and viruses. • After treatment, microorganism and other carried over solids are allowed to settle. • A fraction of sludge is recycle • Excess sludge along with sediment solids has to be disposed off. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

TERTIARY / ADVANCED PROCESS Objectives: v. Nutrients removal, chlorination and dechlorination v. Process added after biological treatment in order to remove specific group/ types of residual v. Can remove + 95% BOD 5, P, SS, bacteria and N Devices/structures: • Filtration –removes SS • Granular Activated Carbon – removes organics • Chemical oxidation – removes oxidizable organics • Expensive to process LARGE VOLUME of WW • Such a polishing process ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (201/2011)

SELECTION OF TREATMENT PROCESS v. Depends on the degree of treatment required to bring the quality of raw wastewater to a permissible level of treated wastewater (eg. Effluent from the treatment plant) v. This ensures that the final effluent is either safe for disposal or acceptable for specific reuse or recycling. v. Other significant factor that will influence the selection of a treatment system are as follows: üAvailability of funds and land at the treatment site üThe topography of land at the treatment site üNon-availability of suitable mechanical equipment and skilled personnel for running and maintaining the plant. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

SELECTION OF TRATMENT PROCESS cont… The points to keep in mind while selecting the treatment process are as follows: 1. Reduction of inorganic material component of wastewater is much easier and cheaper than removal of organics contents of wastewater 2. Removal of suspended solids from wastewater requires lesser time and efforts than of colloidal and dissolved solids 3. In many countries, the Environmental Protection Act requires at least the secondary treatment system for all publicly owned treatment works such as municipal wastewater treatment plant, so that effluent requirements of 30 mg/L for BOD and 100 mg/L of SS are achieved. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION ESSENTIAL CONSIDERATIONS Significant factors that are essential for the design of wastewater treatment processes and plant units include the following: a) Strength and characteristics of wastewater b) Flow rates and their fluctuations c) Mass loading d) Design Criteria e) Hydraulic flow diagram ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… A) STRENGTH & CHARACTERISTICS OF WASTEWATER The strength of wastewater is normally expressed in terms of pollution load, which is determined from the concentrations of significant physical, chemical and biological content of wastewater. B)FLOW RATE AND THEIR FLUCTUATIONS Is the quantity or volume of wastewater in terms of rates. Its is the total quantity of wastewater generated daily and to be treated every day. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… C) MASS LOADING Analysis of mass loading: Involves the determination of the flow rate and mass loading variations Involves determining the simple average or flow weighted average, concentration of specific constituents, mass loading (flow rate times concentration) or sustained mass loading In almost all cases, a flow-weighted average should be used because it is a more accurate method of analysis. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… Simple Average: X=1/n(∑Xi) Where, X=arithmetic average conc of the constituents n=number of observation Xi=average concentration of the constituents during the “i” time period (eg. i=5 if 5 sample for 5 different day) Flow Weighted Average: Xw=(∑xiqi)/∑qi Where, Xw = flow –weighted average conc on the conctituent n=number of observation Xi=average concentration of the constituent during the “i” time period Qi=average flow rate during “i” time period. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… D) DESIGN CRITERIA The data determined through the research and laboratory scale model studies as well as those obtained from the operational experience of field and pilot scale ww treatment facility. The values of such guideline parameters are called design criteria and available in the literature. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… D) DESIGN CRITERIA cont… The most frequently assumed criteria for designing a conventional wastewater treatment plant (WWTP) are as follows: • Detention period or time • Flow through velocity • Settling velocity • Surface loading rate @ over flow rate • Weir loading rate • Organic loading (BOD @ COD @ VSS loading) • Food to Microorganism ratio, F/M • Mean cell Residence Time • Hydraulic Loading • Volumetric Loading • Basin geometry (L: B: D) length, breadth and depth ratio. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

BASIC DESIGN CONSIDERATION cont… E) HYDRAULIC FLOW DIAGRAM Show the detail of wastewater levels as the average and peak flow are prepared. As, it shows the reduced levels or elevations of wastewater surface and the top surfaces of all the units of a treatment plant, level of other significant features like weirs, tops and bottom of units, foundation levels of pump etc. ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)

END FOR PART (A) ERT 417/4 WASTE TREATMENT IN BIOPROCESS INDUSTRY SEM 1 (2010/2011)