FACTS, PATTERNS & PRINCIPLES

Our strategy is to establish the concentration of the contaminants  in the Wastewater prior to determining the treatment units  at various stages to remove the contaminants of interest. These treatment units work on the basic principles of filtration, sedimentation, absorption, gravitation, osmosis and floatation, etc.

According to DPR guidelines and standards, the quality of the liquid component (aqueous layer) of the treated effluent from activities for offshore, nearshore and land locations shall satisfy the following limitations, as shown below:

 

PRE-TREATMENT SYSTEMS

Pre-treatment removes materials that can be easily collected from the wastewater before it damages or clogs pumps and skimmers of primary treatment clarifiers. EAL deploys extensive line of pre-treatment units to protect other units down stream.

Typical pre-treatment includes the following:

• Cone Filters
• Grit Removal System

PRIMARY WASTEWATER TREATMENT

(Physical/Chemical Solids Separation)

DAF (Dissolved Air Flotation) SYSTEMS

Flotation is our major and preferred method of separating solids or liquids from Wastewaters by introducing fine gas bubbles into the Influent stream in a Dissolved Air Flotation (DAF) System.

Our DAF system is designed to handle Wastewaters such as Produce Formation Water and Effluents from oil and gas facilities where the contaminants can be made to float or remain in suspension, like solids, fat, oil, grease, and other organics.

The DAF system design includes influent, effluent, and drain connections, floatation tank, contact chamber, float removal system, settled solids return system, lamella tubes, complete recirculation system including Whitewater pump( microbubble generator) and local PLC based control panel.

Treatment Processes

A. Influent Wastewater:

Influent is induced with chemicals in order to precipitate suspended solids, fat oil & grease and other impurities from the water prior to the physical separation with dissolved air flotation.

The methodologies to inject and mix chemicals:

i) Flocculation Tubes: Flocculation tubes made of Schedule 80 PVC with injection ports for coagulants, pH adjustment and polymers, along with static mixers. The wastewater shall enter the flocculation tubes through a flanged connector and exit into the contact tank through another flanged connector at the header.
ii) Chemical Reaction Tanks: For greater control over the precipitation of impurities, chemical reaction tanks are use. The reaction tanks have mounted mixers with VFDs (Variable Frequency Drives) and means to accept chemicals  from various chemical feed pumps into the tanks. The reaction tanks shall be placed prior to the DAF. The influent wastewater shall first pass through the reaction tanks and then exit into the contact chamber through a flange connector at the header.

B. Contact Chamber:

The influent wastewater shall enter the DAF unit through a flanged influent header into the contact chamber. Simultaneously, the recycle (whitewater) stream shall be mixed with the influent wastewater through a tangential pipe that is connected into the header, creating vortex. The vortex effect results in 100% contact between the air bubbles in the whitewater and the dirty influent water. As the water enters into the contact chamber it shall first encounter an internal weir acting as a secondary coarse bubble separator which provides even distribution and mixing of the process flow across the width of the unit, without any turbulence. The contact chamber has a drain port for removal of heavy solids that may settle in the chamber.

C. Flotation Tank:

The unit consists of a circular flotation tank constructed of 6mm 304 stainless steel plate reinforced with 304 stainless steel tubular circular wall structural supports.

i) The vessel shall be supported on a stainless steel base consisting of vertical and horizontal beams across the width and length of the unit.

ii) The vessel shall be constructed to allow for easy cleaning around and under the unit. The unit shall be designed for above-ground positioning on a suitable concrete pad or steel frame and shall be constructed for indoor or outdoor conditions.

D. Lamella Tubes in Flotation Chamber: To increase efficiency and maintain smaller footprint, the Flotation Chamber shall be filled with Lamella Tubes, whose function is to increase the projected surface area and improve the separation efficiency of the solids from the clear water. The Lamella Tubes shall be made of Polypropylene material with 60° angular slant toward the co-current water flow.  The lamella tubes shall have chevron shape to prevent clogging and 2” spacing between each lamella.

E. Float Removal System: The unit shall be equipped with a chain and flight skimmers to remove top floats, driven by a low speed VFD (Variable Frequency Drive), gear reducer with motor assembly.

 

SECONDARY WASTEWATER TREATMENT

DAF (Dissolved Air Flotation) SYSTEMS

There are five important factors to be considered in a DAF process:

• Air to Solids Ratio is the quantity of air required to float a given amount of solids and fats, oils and greases (FOG’s). Under design conditions of 75 psig at 70°F, the average amount of air dissolved is about 9% by weight. The total suspended solids (TSS) must be analyzed and the appropriate percent recycle rate established. A waste stream of 1,000 mg/L TSS will require a recycle rate of 30-50%, and 2,000 mg/L TSS will likely require 100% recycle of the cleaned water back to the influent stream.

• Hydraulic Loading (gpm/ft2) is total flow rate divided by the effective surface separation area. Design hydraulic loading varies from 1.5 to 5.0 gpm/ft2.

• Weir Overflow Flow Rate must allow for the mechanical separation of the floated solids from the clear water.

• Solids Loading considers the effective surface area of the DAF cell and the total amount of TSS and FOG entering the system. The Wastewater 307
average design load is 1.0 to 3.5 lbs/hr/ft2. The calculation should include the influent TSS and all the chemicals added to condition and flocculate the waste stream. Coagulants and flocculants are used to break emulsified oils and to destabilize colloidal material.

• Solids Handling is required to adequately remove the floated solids and any sediment that may occur.