Kuan-Yeow Show

Anaerobic granulation technology for wastewater treatment

Anaerobic wastewater treatment using granular sludge reactors is a developing technology, in which granular sludge is the core component. So far, around 900 anaerobic granular sludge units have been operated worldwide. Although intensive research attention has been given to anaerobic granules in the past 20 years, the mechanisms responsible for anaerobic granulation and the strategy of how to expedite substantially the formation of granular sludge have not yet been completely clear. This paper reviews the mode of anaerobic granulation, including the mechanisms and models for anaerobic granulation, major factors influencing anaerobic granulation, characteristics of anaerobic granules, anaerobic granulation in other types of reactors, industrial application of anaerobic granulation technology and neural fuzzy model-based control strategy developed for anaerobic systems. Some approaches for future research are outlined.

Use of ash derived from oil-palm waste incineration as a cement replacement material

Abstract The production of palm oil creates large quantity of solid waste by-products. Empty oil-palm fruit bunches discharged from the mill are currently being disposed of by burning in an incinerator. After combustion, a substantial amount of highly caustic ash is produced which creates problems of disposal. This study examines the feasibility of using the ash as a cement replacement material. The experimental results indicate that blended cement containing ash derived from oil-palm waste shows satisfactory setting times and soundness test results. Workability of concrete incorporating the ash is categorized as good, and no segregation was observed. The effects of ash addition on concrete densities and water absorption are insignificant. Compressive strength of the concrete decreases with the ash content in the cement. Up to 10% by weight of ash addition, no adverse effect on the strength was observed for the cubes cured for 1 year. The results suggest that the ash could possibly be blended in small amounts with ordinary Portland cement for concrete making without detrimental effects on long-term strength property.

Utilization of municipal wastewater sludge as building and construction materials

Abstract Sludge is an inevitable by-product of wastewater treatment. Generally, dewatered sludge is disposed of by spreading on the land or by landfilling. For highly urbanized cities, sludge disposal by landfilling might not be appropriate due to limitation of land. Increasingly stringent environmental control regulations have also resulted in limitations on sludge disposal options. Hence, there is an increasing interest in disposal by incineration. Incineration ash will be produced and must be disposed of by other means. The disposal problems can be drastically reduced if sludge can be recycled into building and construction materials. This paper reports the use of sludge and sludge ash as new and non-conventional construction materials as an alternative means of sludge disposal. The properties of the materials made of sludge, the methodology of processing them, and the suitability of the materials for construction applications have been discussed.

Municipal wastewater sludge as cementitious and blended cement materials

Abstract The potential for using wastewater sludge in combination with limestone to produce cementitious building materials is investigated. A ground mixture of the raw materials was incinerated to produce the cement clinker. The effects of raw materials mix compositions, incineration temperatures and durations on various properties of the cement were examined. The experimental results show that under controlled incineration, it is possible to produce the so-called ‘Bio-cement’ from wastewater sludge that would satisfy the strength requirements for masonry cement. When being used as a partial replacement material for portland cement, the Bio-cement can replace up to 30% by weight of ordinary portland cement without deteriorating the mortar strength. Blended cement with up to 10% replacement level not only shows higher strength than control portland cement, it also exhibits a higher rate of strength development at early ages. This paper presents properties of the cements as well as their strength characteristics.

Seafood Processing Wastewater Treatment

The seafood industry consists primarily of many small processing plants, with a number of larger plants located near industry and population centers. Numerous types of seafood are processed, such as mollusks (oysters, clams, scallops), crustaceans (crabs and lobsters), saltwater fishes, and freshwater fishes. As in most processing industries, seafood-processing operations produce wastewater containing substantial contaminants in soluble, colloidal, and particulate forms. The degree of the contamination depends on the particular operation; it may be small (e.g., washing operations), mild (e.g., fish filleting), or heavy (e.g., blood water drained from fish storage tanks). Wastewater from seafood-processing operations can be very high in biochemical oxygen demand (BOD), fat, oil and grease (FOG), and nitrogen content. Literature data for seafood processing operations showed a BOD production of 1–72.5 kg of BOD per tonne of product [1]. White fish filleting processes typically produce 12.5–37.5 kg of BOD for every tonne of product. BOD is derived mainly from the butchering process and general cleaning, and nitrogen originates predominantly from blood in the wastewater stream [1]. It is difficult to generalize the magnitude of the problem created by these wastewater streams, as the impact depends on the strength of the effluent, the rate of discharge, and the assimilatory capacity of the receiving water body. Nevertheless, key pollution parameters must be taken into account when determining the characteristics of a wastewater and evaluating the efficiency of a wastewater treatment system. Section 2 discusses the parameters involved in the characterization of the seafood processing wastewater. Pretreatment and primary treatment for seafood processing wastewater are presented in Section 14.3. These are the simplest operations to reduce contaminant load and remove oil and grease from an effluent of seafood processing wastewater. Common pretreatments for seafoodprocessing wastewater include screening, settling, equalization, and dissolved air flotation. Section 14.4 focuses on biological treatments for seafood processing wastewater, namely aerobic and anaerobic treatments. The most common operations of biological treatments are also described in this section.