WELCOME TO PRENTEC

Since its foundation in 1974, PRENTEC has continued to grow from strength to strength. The manufacturing facilities were doubled in 1992, and the quality assurance procedures are accepted by all international industrial groups and mining houses.

 

Package Plants

1 PRENTEC SBR PACKAGE PLANTS

PRENTEC factory built SBR package plants are designed to meet the URBAN WASTE WATER TREATMENT REGULATIONS 1994, No. 2842 implementing the European Council Directive 91/271/EEC.Plant are designed for the final discharge effluent to meet the South African General Limits.

2 DESIGN PARAMETERS

The PRENTEC SBR Package Plant design is based on the following parameters:

- Hydraulic loading 160 ℓ capita per day
- Organic loading 60 g BOD per capita per day 7.5 g
  Ammonia per capita per day
PRENTEC SBR Package Plants shall produce a final effluent quality of 20:25 (BOD:SS) standard or better.
Two or more units operating in parallel shall produce a final effluent of 10:15 (BOD:SS)

3 INTRODUCTION

In the field of domestic sewage treatment, very small communities can produce volumetric loadings in the range from 5 m³/d to 100 m³/d.

It is accepted worldwide that the most viable process for treating sewage is that of “total oxidation by means of the extended aeration principle of the activated sludge process” executed in a batch reactor. This process results in the production of a high quality final effluent and a fully stabilised waste sludge.

Other processes such as anaerobic/aerobic combination (i.e. bubble aeration, biodisc plants, biofiltration, etc.) are also marketed but none of them have proved to be as viable and effective as the total oxidation process.

4 STANDARD UNIT

PRENTEC manufacture, pre-assemble and factory test three different sizes of SBR activated sludge sewage treatment plants.

The reactor basins are manufactured from sandblasted and painted mild steel plate and the biological process is fully automated. For ease of transport in 6m standard containers, the reactor basin is manufactured in sections and reassembled on site.

Model No Capita Hydraulic Load(m3/d)   Organic Load kg BOD/d Reactor Size Diam. X Length Operating Weight(tonne)
SBR PP 100 100 16   6 2, 0 x 6,0 35
SBR PP 300 300 48   18 3, 6 x 8,0 90
SBR PP 600 600 96   36 4, 4 x 9,5 160

5 PLANT CONCEPT

The hydraulic and organic loads being fed to the plant can vary significantly from hour to hour. It is therefore essential that the plant is designed to accept and effectively treat these large variations in organic and hydraulic loading. Batch treatment overcomes the problems associated with load variation.

The PRENTEC Bioreactor treats the sewage utilising total oxidation by the extended aeration principle of the activated sludge process and includes the following steps:

  • Aeration
  • Settling
  • Decanting of treated effluent
  • Sludge stabilisation
  • Waste sludge discharge

 

6 PROCESS DESCRIPTION

Refer to PRENTEC Drawing: A3-STD-SA-211 – Plant Arrangement.

Screened raw sewage is fed to the SBR reactor basin where the organic constituents are biologically oxidised by the micro-organism population present in the activated sludge.

The operation of the aeration tank is of a batch type system, i.e. tank contents are aerated. Treated and the effluent decanted upto three times per day at average flow. When the volume reaches a predetermined level, the fully automatic control system shuts down the aerator, allows a quiescent settling period, and then starts the effluent discharge decanting mechanism mounted on the floating structure. Since the decanter is submerged, the scum and floating matter are not discharged with the final effluent.

The effluent discharge cycle is automatically stopped by means of a low level switch, which is positioned such that the effluent pump stops before any sludge would be discharged with the effluent. At the same time the next aeration cycle is commenced.

From time to time stabilised excess sludge must be discharged out for disposal.

Additional capacity has been built into the aeration basin to enable the sludge to be built up until it is convenient to dispose of the excess sludge.

Aeration of the sewage is achieved by a mechanical surface aerator mounted on a floating structure. The design of the aerator provides complete flexibility in operation and the oxygen input is readily controllable.

The biological treatment process is automatically controlled via a PLC mounted in a weather proof panel.

7 EQUIPMENT SPECIFICATION

The PRENTEC Bioreator plant consists of:

7.1 REACTOR TANK

  • tank manufactured from welded mild steel sheet sandblasted and painted or 3CR12;
  • floating aerator structure manufactured from mild steel and hot dip galvanised;
  • geared motor 400 V TEFC 1450 rpm;
  • surface aerator Model K;
  • final effluent decanter;
  • waste sludge discharge valves;
  • level controls;

7.2 CONTROL PANEL

  • electrical control equipment;
  • PLC unit;

7.3 PIPE CONNECTIONS/PIPING

  • Mild steel piping hot dip galvanised;
  • Flexible piping;

8 CIVIL WORKS

The Client shall be responsible for:

  • All earthworks;
  • Foundation to support the package sewage treatment plant
  • Backfilling around the reactor tank if it is to be installed into the ground;

9 BATTERY LIMITS

  1. The Client shall connect up the screened raw sewage line to the flanged connection on the reactor tank;
  2. The Client shall pipe away the final effluent from the chlorine tank;
  3. The Client shall connect up the 400 V power supply to the control box;
  4. The Client to provide a potable water supply stand pipe if available;
  5. The Client to provide facilities to dispose of the excess wasted activated sludge. Sludge drying beds can be provided in the form of PRENTEC precast concrete panel beds.

10 CHARACTERISTICS OF PRENTEC SBR PACKAGE SEWAGE TREATMENT PLANTS

1. TOTAL CAPITAL COSTS  
  - are reduced by the elimination of settling tanks and sludge recirculation equipment.
2. PLANT RELIABILITY  
  - the installation offers greater flexibility and reliability of operation.
3. OPERATION CONTROL  
  - the system completely eliminates the operating problems and housekeeping requirements normally associated with the day to day control of activated sludge plants, e.g. sludge bulking, sludge recirculation, washing down clarifiers, etc.
4. PLANT PERFORMANCE  
  - are not sensitive either to large daily or seasonal fluctuations or organic or hydraulic loads applied to the plant thus guaranteeing a consistently high quality effluent.
5. WASTE EXCESS SLUDGE  
  - the total volume of excess sludge produced is reduced due to the longer average sludge age and higher recommended operating level of the mixed liquor suspended solids. The sludge disposal requirements are therefore reduced and the sludge produced is more readily treatable.
6. FLOW MEASUREMENTS  
  - the measurement of the treatment plant throughput is measured in a batch fashion and hence offers a much greater accuracy.
7. LABOUR / MAINTENANCE  
  - is greatly reduced due to the plant’s automatic mode of operation and simplicity of plant construction.
8. PLANT EXTENTIONS  
  - PRENTEC plants are constructed in a modular fashion hence future extensions are simple to implement and extremely cost effective
9. FACTORY MANUFACTURE  
  - the plants are manufactured and pre-assembled in PRENTEC’s Factory under strict quality control procedures thus guaranteeing a high quality unit.
Company Profile  |  Capabilities  |  Manufacturing  |  Projects  |  News  |  SEWPACKSA  |  Contact Us  |  
Copyright (c) Prentect (Pty) Ltd, 2010, Developed by ISPDATA