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This study partially replaced the clay with sewer sludge (SS) and rice husk (RH-SS) to make fired bricks. The brick samples were examed in terms of shrinkage, water absorption, and compressive strength. Besides, they were analyzed via XRD and metal extraction to determine the heavy metal residuals in the products. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight. These brick samples complied with the technical standard for clay brick production, in which the compressive strength was more than 7.5 MPa, water absorption was from 11–16%, and the linear shrinkage was all less than 5%. The rice husk addition helped mitigate the heavy metal residuals in the bricks and leaching liquid, in which all the values were lower than the US-EPA maximum concentration of contaminants for toxicity characteristics. Implications: Previous studies have proved the possibility of mixing sewage sludge from different origins (sewage sludge, river sediment, canal sediment, sewer sediment, etc.) with clay and some wastes to make bricks. In which, mostof the studies used sewage sludge from wastewater treatment plants, very fewdealt with lake/river or sewer sediment. This study shall be the first to study the possibility of employing sewer sediments with the addition of rice husk powder to achieve two targets, including (1) the reuse of biowaste and sludge for brick fabrication and (2) the reduction of heavy metals in final calcined bricks. Different ratios of the rice-husk blended sewer sludge (RH-SS) – clay mixture shall be tested to find the optimized compositions. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight, which meant reduce 30% of clay in the brick production. The final products were proved to meet the quality standard in terms of compressive strength (more than 10 MPa), water absorption(from 11–16%), and the linear shrinkage (less than 5%). Larger scale of this study can be an evident to recommend for policy change in the waste reuse in construction field. [ABSTRACT FROM AUTHOR]

The geographic and spatial distribution of ayu Plecoglossus altivelis (Temminck and Schlegel 1846) larvae were determined in the rivers of northern Vietnam. Collections were made with a larval net and a small seine net along the Tien Yen and Kalong Rivers from 2010 to 2015. Thirty individuals were collected in the Tien Yen and 160 from the Kalong. This is the first record of larval and juvenile ayu from the Tien Yen, which constitutes the southernmost range of this species. Collected fish were primarily at the preflexion stage (4.0-59.1 mm body length, BL). Mean temperature, salinity, turbidity and dissolved oxygen where larvae and juveniles were collected ranged from ca. 15.7-20.0 °C, ca. 5.6-20.7 psu, 2.7-14.6 NTU, and 7.7-10.0 mg.L-1, respectively. Larvae began to appear in November for the Kalong and in December for the Tien Yen, primarily occurring at stations far from the river mouth. Larvae <7.0 mm BL were more widely distributed across both estuaries, migrating to shoreline waters after reaching a size of ca. 15.0 mm BL in February. With relatively few larvae being observed in the southernmost region, the Tien Yen estuary may be a focus of conservation efforts of this annual amphidromous fish. [ABSTRACT FROM AUTHOR]