Westcountry Waste Management.

We have purchased a treatment works at Lee Mill where we can treat our waste in both an efficient and environmentally friendly manner. The site will also act as an additional location to keep our lorries and tankers which will not only lessen the concentration of traffic in the Yelverton area but also allow us to operate more responsively and efficiently. Additionally, the position of the plant, just off the A38 between Plymouth and Exeter, will allow us to conserve fuel and save time and consequently we plan to extend further in the future.

Introduction

Sewage treatment is a multi-stage process to renovate wastewater before it re-enters a water stream or applied to the land. The goal is to reduce or remove organic matter and solids by using a dissolved air flotation (DAF) clarification system for the treatment and removal of suspended solids.

The plant is capable of processing a maximum throughput of 5 m3/hr. The treatment will consist of the addition of aluminium sulphate and sodium hydroxide to chemically precipitate the impurities and to control the process pH.

At present the consent to discharge is 300c.o.d

Preliminary treatment (Screens)

Untreated effluent from a tanker will discharge into the first section of the process which will screen out, or separate debris i.e. Sticks, hygiene products, large food particles, sand, gravel, toys, etc, are removed at this stage to protect the pumping and other equipment in the treatment process.

Primary Treatment

Balance Tanks

From the primary tank it is fed into the balance tanks, which is fitted with a submersible mixer. The mixer minimises fat separation and ensures that a homogenous effluent is fed to the process plant. The balance tank is connected to the surge tank by overflow pipe. The surge tank is fitted with level probes that automatically transfers overflowed effluent back to the balance tank by operating the transfer pump.

Secondary Treatment (Biological Tank)

Secondary treatment is a biological treatment process to remove dissolved organic matter from wastewater. Sewage micro organisms are cultivated and added to the waste water.

Final Settlement Tank

After the micro organisms have been suspended in the waste water for several hours, they are settled out as sludge. Some of the sludge is pumped back into the incoming wastewater to provide “seed” micro organisms. The remainder is wasted and sent on to the decant tanks.

Decant Tanks

Sludges are generated through the sewage treatment process. Primary sludges, material that settles out during primary treatment will require treatment prior to disposal. Secondary sludges are the extra micro organisms from the biological treatment process.

Monitoring

Waste water treatment process requires careful management to ensure the correct operation.  The management team at Glanville Environmental are committed to ensuring all its staff are trained and capable of monitoring the incoming sewage, the treatment process and the final effluent.