In this article we will discuss about the design of trickling filters. Organic Loading Rate: Organic loading rate and the recirculation ratio are the main considerations in the design, where the organic loading rate is decided; the required filter volume is calculated. Now the depth and surface area of the filter are suitably chosen to secure hydraulic loading rates within [...]
In this essay we will discuss about:- 1. Meaning of Activated Sludge 2. The Activated Sludge Process 3. Variables 4. Capacity of Aeration Tank and Detention Period 5. Return Activated Sludge 6. Advantages and Disadvantages 7. Operation of Activated Sludge Plant. Essay # 1. Meaning of Activated Sludge: When sewage is passed or trickles through a grit bed, the sewage [...]
Aeration units are the main units of the activated sludge process, the main aims of which are to supply oxygen to the sewage; to keep the return sludge aerobic and to mix up the return sludge with sewage thoroughly. All the aeration units can be broadly classified as follows: 1. Diffuser Air Units 2. Mechanical Aeration Units 3. Combined Mechanical [...]
Following are the various types of troubles which occasionally occur at the site and operation of trickling filters: 1. Odour Nuisance 2. Ponding Nuisance 3. The Fly Nuisance. Trouble # 1. Odour Nuisance: It is used due to anaerobic decomposition, sludging and undesirable growth. The odour nuisance can be eliminated by preventing the conditions responsible for it. Following are the [...]
The filters which are mostly used in sewage treatment can be classified as follows: 1. The Intermittent Sand Filters 2. The Contact Beds 3. The Trickling Filters. 1. Intermittent Sand Filters: These are the early development of sewage treatment units. These are similar in Construction to the slow-sand filter of water treatment. These require larger area, due to which these [...]
Fig 16.4 shows the section through a trickling filter. It essentially consists of a masonry or R.C.C. tank which is circular or rectangular in plan. Coarse aggregate of impervious nature is filled in this tank which acts as filtering media. The under-drainage system is provided in the bed to collect the Aggregate effluent. Fig. 16.4 (a) shows the under-drainage system [...]
The following are the various types of activated sludge process: 1. Tapered Aeration 2. Step Aeration 3. High Rate Treatment or Modified Aeration 4. Two Stage Aeration 5. Activated Aeration 6. Reaeration 7. Contact Stabilization 8. Complete Mix 9. Extended Aeration Method. Type # 1. Tapered Aeration: This is also called controlled aeration. If samples are collected at various points [...]